Mometasone furoate has minimal effects on the hypothalamic-pituitary-adrenal axis when delivered at high doses

STUDY OBJECTIVES

To investigate the potential for mometasone furoate (MF) to exert systemic effects following administration by dry powder inhaler (DPI) or metered-dose inhaler (MDI).

DESIGN

Three randomized, evaluator-blind, placebo-controlled, parallel-group, 28-day studies.

PATIENTS

Adults with mild-to-moderate persistent asthma.

INTERVENTIONS

Study 1 (12 patients per treatment group; MF DPI at 200 microg bid, 400 microg qd, 800 microg qd, or 1,200 microg qd). Study 2 (16 patients per treatment group; MF DPI at 400 microg bid or 800 microg bid, or oral prednisone at 10 mg qd). Study 3 (16 patients per treatment group; MF MDI at 400 microg bid or 800 microg bid, or fluticasone propionate [FP] at 880 microg bid by MDI).

MEASUREMENTS AND RESULTS

Study 1. Plasma concentrations were near the lower limit of quantitation (50 pg/mL) at the MF DPI 400-microg qd dosage and approximately 250 pg/mL at the 1,200-microg qd dosage. The area under the curve for serum cortisol concentrations over 24 h (AUC(24)) was essentially unaltered at all doses. Study 2. Plasma levels over days 7 to 28 were 100.3 +/- 5.9 pg/mL (mean +/- SEM) for MF DPI 400 microg bid, and 181.0 +/- 10.9 pg/mL for 800 microg bid. Although there were relatively low levels of suppression (19 to 25%) at earlier time points for MF DPI 400 microg bid, serum cortisol AUC(24) levels at day 28 were similar to placebo. MF DPI 800 microg bid and oral prednisone both decreased serum cortisol AUC(24) levels at days 7 to 28 by 28.0 +/- 8.3% and 67.2 +/- 3.6%, respectively. The response to cosyntropin was normal in 15, 14, 11, and 1 of the patients in the placebo, MF DPI 400 microg bid, MF DPI 800 microg bid, and prednisone groups, respectively. Study 3. MF MDI caused even less systemic exposure than by DPI. MF MDI 800 microg bid (24.0 +/- 3.1%) and FP (51.7 +/- 3.8%) caused a significant decrease in serum cortisol AUC(24) on days 14 to 28. MF MDI 400 microg bid was similar to placebo treatment at all time points.

CONCLUSIONS

The MF 800-microg bid dosage (1,600 microg/d), which is twice the highest projected clinical dosage, represents the lower limit for consistently detectable systemic effects of MF.

Evaluation of the pharmacokinetics and electrocardiographic pharmacodynamics of loratadine with concomitant administration of ketoconazole or cimetidine

AIMS

To evaluate whether ketoconazole or cimetidine alter the pharmacokinetics of loratadine, or its major metabolite, desloratadine (DCL), or alter the effects of loratadine or DCL on electrocardiographic repolarization in healthy adult volunteers.

METHODS

Two randomized, evaluator-blind, multiple-dose, three-way crossover drug interaction studies were performed. In each study, subjects received three 10 day treatments in random sequence, separated by a 14 day washout period. The treatments were loratadine alone, cimetidine or ketoconazole alone, or loratadine plus cimetidine or ketoconazole. The primary study endpoint was the difference in mean QTc intervals from baseline to day 10. In addition, plasma concentrations of loratadine, DCL, and ketoconazole or cimetidine were obtained on day 10.

RESULTS

Concomitant administration of loratadine and ketoconazole significantly increased the loratadine plasma concentrations (307%; 90% CI 205-428%) and DCL concentrations (73%; 62-85%) compared with administration of loratadine alone. Concomitant administration of loratadine and cimetidine significantly increased the loratadine plasma concentrations (103% increase; 70-142%) but not DCL concentrations (6% increase; 1-11%) compared with administration of loratadine alone. Cimetidine or ketoconazole plasma concentrations were unaffected by coadministration with loratadine. Despite increased concentrations of loratadine and DCL, there were no statistically significant differences for the primary electrocardiographic repolarization parameter (QTc) among any of the treatment groups. No other clinically relevant changes in the safety profile of loratadine were observed as assessed by electrocardiographic parameters (mean (90% CI) QTc changes: loratadine vs loratadine + ketoconazole = 3.6 ms (-2.2, 9.4); loratadine vs loratadine + cimetidine = 3.2 ms (-1.6, 7.9)), clinical laboratory tests, vital signs, and adverse events.

CONCLUSIONS

Loratadine 10 mg daily was devoid of any effects on electrocardiographic parameters when coadministered for 10 days with therapeutic doses of ketoconazole or cimetidine in healthy volunteers. It is concluded that, although there was a significant pharmacokinetic drug interaction between ketoconazole or cimetidine and loratadine, this effect was not accompanied by a change in the QTc interval in healthy adult volunteers.

Regional lung deposition of a technetium 99m-labeled formulation of mometasone furoate administered by hydrofluoroalkane 227 metered-dose inhaler

BACKGROUND

A new inhaled suspension formulation of mometasone furoate (MF), a potent corticosteroid with minimal systemic availability, has been developed for the treatment of asthma. This formulation is delivered by metered-dose inhaler (MDI) using the nonchlorofluorocarbon propellant hydrofluoroalkane 227 (HFA-227).

OBJECTIVE

The primary goal of this study was to determine the respiratory tract deposition of this formulation of MF. A secondary objective was to measure plasma concentrations of MF and a putative metabolite, 6-X-OH MF, to determine the systemic exposure to corticosteroid.

METHODS

This was a single-dose, open-label study in which 200 microg of technetium 99m (99mTc)-radiolabeled MF was administered to patients with asthma. Gamma scintigraphy was used to quantify lung, oropharyngeal, stomach, and MDI mouthpiece deposition patterns of MF.

RESULTS

Eleven patients, aged 21 to 47 years, with a history of asthma were enrolled in and completed the study. The mean (+/- SD) whole lung deposition of MF was 13.9%+/-5.7% of the metered (ex-valve) dose. The central lung zone received 5.3%+/-2.8% of the dose; the intermediate zone received 4.7%+/-1.9%; and peripheral lung deposition was 4.0%+/-1.5%. The mean (+/- SD) ratio of peripheral to central lung deposition was 0.8+/-0.2. Oropharyngeal deposition was 79.1%+/-8.7% of the ex-valve dose, with 6.3%+/-7.8% deposited on the MDI mouthpiece and 0.7%+/-0.5% exhaled. The majority of plasma samples taken for analysis of MF and 6-13-OH MF concentrations were below the limit of quantification (50 pg/mL) in all patients after inhalation of 200 microg 99mTc-labeled ME CONCLUSION: The lung deposition of MF when administered via HFA-227 MDI is comparable to the 10 to 20% lung deposition seen with other corticosteroid suspension for- mulations administered by MDI that have demonstrated effectiveness in the treatment of asthma.

Bioavailability and metabolism of mometasone furoate following administration by metered-dose and dry-powder inhalers in healthy human volunteers

These studies were conducted to assess the systemic bioavailability of mometasone furoate (MF) administered by both the dry-powder inhaler (DPI) and the metered-dose inhaler with an alternate propellant (MDI-AP). The pharmacokinetics of single doses (400 micrograms) of MF administered by intravenous (i.v.) and inhalation routes was assessed in a randomized, three-way crossover study involving 24 healthy volunteers. In a separate study, 6 healthy subjects were administered a single dose of tritiated (3H-) MF by DPI, and the radioactivity in blood, urine, feces, and expired air was determined. Following i.v. administration, MF was detected in all subjects for at least 8 hours postdose. The half-life (t1/2) following i.v. administration was 4.5 hours. In contrast, following DPI administration, plasma MF concentrations were below the limit of quantification (LOQ, 50 pg/mL) for many subjects (10 of 24), and the systemic bioavailability by this route was estimated to be less than 1%. Only two plasma samples following MDI-AP administration had plasma concentrations of MF above the LOQ indicating no detectable systemic bioavailability in 92% of the subjects. A separate study with 6 healthy male subjects administered a single dose of 3H-MF (200 microCi) by DPI revealed that much of the dose (approximately 41%) was excreted unchanged in the feces (0-72 hours), while that which was absorbed was extensively metabolized. These results indicate that inhaled MF has negligible systemic bioavailability and is extensively metabolized and should therefore be well tolerated in the chronic treatment of asthma.

Population pharmacokinetics of temozolomide in cancer patients

PURPOSE

To evaluate covariate effects on the pharmacokinetics of temozolomide in cancer patients, and to explore the dose-pharmacokinetics-toxicity relationship of temozolomide.

METHODS

Non-linear mixed-effects modeling approach was used to analyze the data from 445 patients enrolled in eleven Phase I and Phase II clinical trials. All patients in the phase I trials had advanced cancer. Patients in the phase II trials had anaplastic astrocytoma (AA), glioblastoma multiforme (GBM) or malignant melanoma (MM). A sparse sampling scheme was prospectively developed using Phase I data and was successfully implemented in Phase II trials. Population factors included age, gender, height (HT), weight (WT), body surface area (BSA), serum creatinine (Sr.Cr.), estimated creatinine clearance, serum chemistry data as indices of hepatic function and disease, smoking status, and selected concomitant medications. Descriptive statistics were used to summarize the toxicity and temozolomide dose and exposure relationship.

RESULTS

The pharmacokinetics of temozolomide follows a one-compartment model with first order absorption and elimination. Temozolomide clearance (CL) increased with BSA for both genders. The population mean clearance for GBM or AA patients was 11.2 L/hr for male with BSA equal to 2.0 m2, and 8.8 L/hr for female with BSA equal to 1.7 m2. The mean clearance for MM patients was slightly higher. The inter-subject variability in clearance was 15%, and the residual variability was 26%. Other factors investigated in this analysis had little effect on clearance. The overall incidence of neutropenia and thrombocytopenia were 5-8%. Temozolomide dose and AUC did not predict nadir neutrophil and platelet counts due to large variability in counts.

CONCLUSIONS

The current dose regimen is administered according to BSA which is the most important factor influencing temozolomide clearance. No further dose adjustment is required.

The pharmacokinetics, electrocardiographic effects, and tolerability of loratadine syrup in children aged 2 to 5 years

OBJECTIVE

We assessed the pharmacokinetics and tolerability of 5 mg loratadine syrup (1 mg/mL) in children aged 2 to 5 years.

METHODS

Two studies were undertaken. A single-dose, open-label bioavailability study was performed to characterize the pharmacokinetic profiles of loratadine and its metabolite desloratadine. Plasma concentrations of loratadine and desloratadine were determined at 0, 1, 2, 4, 8, 12, 24, 48, and 72 hours after a single administration of 5 mg loratadine syrup to 18 healthy children (11 male, 7 female; 12 black, 5 white, 1 other; mean age +/- SD, 3.8 +/- 1.1 years; mean weight +/- SD, 17.4 +/- 4.4 kg). In addition, a randomized, double-blind, placebo-controlled, parallel-group study was performed to assess the tolerability of 5 mg loratadine syrup after multiple doses. Loratadine (n = 60) or placebo (n = 61) was given once daily for 15 days to children with a history of allergic rhinitis or chronic idiopathic urticaria. In the loratadine group, 27 boys and 33 girls (52 white, 8 black) were enrolled, with a mean age +/- SD of 3.67 +/- 1.13 years and a mean weight +/- SD of 17.2 +/- 3.8 kg. In the placebo group, 27 boys and 34 girls (53 white, 7 black, 1 Asian) were enrolled, with a mean age +/- SD of 3.52 +/- 1.12 years and a mean weight +/- SD of 17.3 +/- 2.9 kg. Tolerability was assessed based on electrocardiographic results, occurrence of adverse events, changes in vital signs, and results of laboratory tests and physical examinations.

RESULTS

The peak plasma concentrations of loratadine and desloratadine were 7.78 and 5.09 ng/mL, respectively, observed 1.17 and 2.33 hours after administration of loratadine; the areas under the plasma concentration-time curve to the last quantifiable time point for loratadine and desloratadine were 16.7 and 87.2 ng x h/mL, respectively. Single and multiple doses were well tolerated, with no adverse events occurring with greater frequency after multiple doses of loratadine than after placebo. Electrocardiographic parameters were not altered by loratadine compared with placebo. There were no clinically meaningful changes in other tolerability assessments.

CONCLUSION

Loratadine was well tolerated in this small, selected group of children aged 2 to 5 years at a dose providing exposure similar to that with the adult dose (ie, 10 mg once daily).

In vivo effects of interleukin-10 on human cytochrome P450 activity

BACKGROUND

Injection of lipopolysaccharide into human volunteers leads to an increase in serum interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha and a significant decrease in cytochrome P450 (CYP)-mediated drug metabolism. The in vivo effects of the noninflammatory cytokine interleukin-10 (IL-10) on CYP-mediated drug metabolism was examined.

METHODS

IL-10 (8 microg/kg) and placebo were administered for 6 days to 12 healthy volunteers in a double-blind crossover study. Tolbutamide (CYP2C9), caffeine (CYP1A2), dextromethorphan (CYP2D6 and CYP3A), and midazolam (CYP3A) were administered on days 4 and 5 to determine individual CYP activities.

RESULTS

Few clinically apparent side effects were observed after administration of IL-10; however, blood chemistries reflected an acute-phase response. A significant drop in serum albumin (mean percentage change +/- SD between groups; 4.7% +/- 6.0%, P < or = .02), a significant increase in serum ferritin (736% +/- 717%, P < or = .001), and a significant reduction in platelet count (49% +/- 12%, P < or = .0001) was observed after administration of IL-10. IL-10 significantly (P < or = .02) decreased CYP3A activity 12% +/- 17%, as reflected by midazolam clearance. CYP2C9 activity was significantly (P < or = .005) increased by 38% +/- 35%, as reflected by the tolbutamide urinary metabolic ratio and oral clearance. However, administration of IL-10 resulted in a 40% increase in the fraction unbound of tolbutamide. Therefore no difference in the unbound clearance of tolbutamide was observed between placebo (23.3 +/- 9.7 L/h) or IL-10 (23.5 +/- 11.4 L/h) administration. No significant changes in either CYP1A2 or CYP2D6 activities were observed between placebo and treatment arms of the study.

CONCLUSION

IL-10 administration resulted in an acute-phase response. Administration of IL-10 did not alter CYP1A2, CYP2C9, and CYP2D6 activities. CYP3A-mediated biotransformation was reduced by administration of IL-10.

Disposition of recombinant human interleukin-10 in subjects with various degrees of renal function

The pharmacokinetics of intravenously administered recombinant human interleukin-10 (rHuIL-10) were evaluated in 18 subjects with creatinine clearances (Clcr) between 2.7 and 116.7 mL/min/1.73 m2. Serum samples for rHuIL-10 were obtained over a 48-hour period after a single 25 micrograms/kg i.v. bolus infusion. AUC, total body clearance (Clp), and steady-state volume of distribution (Vdss) were derived by compartmental methods. Analysis of serum concentrations showed statistically significant group differences for log-transformed AUC and original scale Clp (p < 0.01). The AUC and effective half-life increased, while the mean Clp of rHuIL-10 decreased as renal function declined. A linear relationship between AUC and Clcr as well as Clp and Clcr demonstrates that the disposition of rHuIL-10 is altered in subjects with renal insufficiency. No serious adverse events were noted.

The penetration of ceftibuten into the respiratory tract

STUDY OBJECTIVE

To determine the penetration of ceftibuten into various respiratory tissues and fluids.

DESIGN

Single-dose, open-label, pharmacokinetic study.

SETTING

Veterans Administration Medical Center.

PATIENTS

Twelve hospitalized men aged 34 to 75 years with a variety of noninfectious pulmonary symptoms/diseases.

INTERVENTIONS

Patients received a single oral dose of ceftibuten, 200 mg, prior to undergoing diagnostic fiberoptic bronchoscopy. Plasma samples for the determination of ceftibuten concentrations were collected pretreatment and up to 12 h postdosing. Nasal secretions, tracheal secretions, BAL fluid, and lung tissue from a biopsy were obtained at bronchoscopy from 2 to 7 h postdosing.

MEASUREMENTS AND RESULTS

Mean pharmacokinetic parameters for ceftibuten in plasma were the following: maximum observed plasma concentration (Cmax), 8.77 microg/mL; time to reach Cmax, 2.2 h; area under the plasma concentration-time curve extraploated to infinity, 49.21 microg/h/mL; and terminal elimination half-life, 3.17 h. These parameters were similar to those obtained in studies using healthy volunteers. Mean penetration of ceftibuten into nasal, tracheal, and bronchial secretions was 47%, 50%, and 30%, respectively. Mean penetration into BAL fluid was 81%, whereas penetration into lung tissue was 39%. No patient experienced any adverse effects related to ceftibuten.

CONCLUSIONS

Ceftibuten penetrates well into various tissues and fluids of the upper and lower respiratory tracts. The results support the activity of ceftibuten in the treatment of upper and lower respiratory tract infections.

Cardiovascular safety of second-generation antihistamines

Reports of serious cardiac arrhythmia associated with some second-generation antihistamines have prompted concern for their prescription. This article reviews the nature of the adverse events reported and concludes that the blockade of potassium channels, particularly the subtype responsible for the rapid component of the delayed rectifier current (IKr), is largely responsible for such adverse cardiac events. Consequently, antihistamines with little or no interaction with these channels are expected to have the greatest safety margin. The main cardiac arrhythmia of concern is that of torsades de pointes, a potentially fatal phenomenon characterized by prolonged ventricular depolarization that manifests as a prolonged QT interval and polymorphic ventricular tachycardia, with twisting of the QRS complexes. Based on pre-clinical and clinical evidence, it appears that loratadine, cetirizine, and fexofenadine are safe from cardiac arrhythmia via the IKr channel, whereas astemizole and terfenadine have a propensity to cause ventricular tachyarrhythmias.

Pharmacokinetics of flutamide in patients with renal insufficiency

AIMS

The aim of this study was to determine the pharmacokinetic parameters of flutamide, a nonsteroidal antiandrogenic compound, and its pharmacologically active metabolite, hydroxyflutamide, in renal insufficiency. Haemodialysis (HD) clearance of flutamide and hydroxyflutamide was also determined.

METHODS

Pharmacokinetic parameters were assessed for flutamide and hydroxyflutamide in 26 male subjects with normal renal function (creatinine clearance by 24 h urine collection, CLcr, greater than 80 ml min(-1) 1.73 m(-2); n=6) or reduced renal function; CLcr=50-80 (n=7), 30-49 (n=3), 5-29 (n=4), and <5 ml min(-1) 1.73 m(-2)-HD (n=6), following a single, oral 250 mg flutamide dose. Subjects undergoing HD received a second 250 mg dose of flutamide 4 h prior to HD; blood and dialysate were collected during HD to determine dialysability of flutamide and hydroxyflutamide.

RESULTS

Cmax, tmax, AUC, t1/2, and renal clearance of flutamide and hydroxyflutamide did not differ between groups. Less than 1% of the dose appeared in dialysate as hydroxyflutamide. No serious adverse events were observed.

CONCLUSIONS

Renal function did not affect flutamide nor hydroxyflutamide disposition. HD did not alter hydroxyflutamide pharmacokinetics. Dosing adjustments for renal impairment or HD are not indicated for flutamide.

Pharmacokinetics and leukocyte responses of recombinant human interleukin-10

PURPOSE

To study the pharmacokinetics and ex vivo leukocyte responses of recombinant human IL-10 (rHuIL-10) following single s.c. and i.v. dosing.

METHODS

A randomized two-way cross-over study was undertaken in 17 healthy volunteers in which rHuIL-10 was administered as 25 microg/kg s.c. and i.v. doses. Blood samples were collected for 48 hr after dosing to determine serum IL-10 concentrations. Inhibitory activity of IL-10 on ex vivo production of inflammatory cytokines (TNF-alpha and IL-1beta) by LPS-treated peripheral blood cells were measured over 96 hr.

RESULTS

A physiologically-relevant modeling approach was developed to determine the pharmacokinetics for two routes of administration (s.c. and i.v.). The i.v. dose showed polyexponential disposition with CL of 65 mL/kg/hr, Vss of 70 mL/kg, and t1/2 of 1.94 hr. Absolute bioavailability averaged 42% for s.c. dosing which produced lower but sustained concentrations. Substantial and prolonged suppression of TNF-alpha and IL-1beta production was achieved during IL-10 treatment. The Hill Function was used to account for the joint concentration-dependent immunosuppressive action of rHuIL-10 after both i.v. and s.c. doses. The IC50 values were about 0.03 ng/ml and Imax values were about 0.85 for both TNF-alpha and IL-1beta suppression. The degree of change as well as the duration of leukocyte response was greater after s.c. administration than after i.v. administration.

CONCLUSION

rHuIL-10 shows favorable PKPD characteristics especially by the s.c. route of administration which produced prolonged suppression of cytokine production (ex vivo) which may be applicable in various immune-related disorders.

Disposition of 14C-eptifibatide after intravenous administration to healthy men

Eptifibatide, a synthetic peptide inhibitor of the platelet glycoprotein IIb/IIIa receptor, has been studied as an antithrombotic agent in a variety of acute ischemic coronary syndromes. The purpose of the present study was to characterize the disposition of 14C-eptifibatide in man after a single intravenous (i.v.) bolus dose. 14C-Eptifibatide (approximately 50 microCi) was administered to eight healthy men as a single 135-microgram/kg i.v. bolus. Blood, breath carbon dioxide, urine, and fecal samples were collected for up to 72 hours postdose and analyzed for radioactivity by liquid scintillation spectrometry. Plasma and urine samples were also assayed by liquid chromatography with mass spectrometry for eptifibatide and deamidated eptifibatide (DE). Mean (+/- SD) peak plasma eptifibatide concentrations of 879 +/- 251 ng/mL were achieved at the first sampling time (5 minutes), and concentrations then generally declined biexponentially, with a mean distribution half-life of 5 +/- 2.5 minutes and a mean terminal elimination half-life of 1.13 +/- 0.17 hours. Plasma eptifibatide concentrations and radioactivity declined in parallel, with most of the radioactivity (82.4%) attributed to eptifibatide. A total of approximately 73% of administered radioactivity was recovered in the 72-hour period following 14C-eptifibatide dosing. The primary route of elimination was urinary (98% of the total recovered radioactivity), whereas fecal (1.5%) and breath (0.8%) excretion was small. Eptifibatide is cleared by both renal and nonrenal mechanisms, with renal clearance accounting for approximately 40% of total body clearance. Within the first 24 hours, the drug is primarily excreted in the urine as unmodified eptifibatide (34%), DE (19%), and more polar metabolites (13%).

A systemic bioactivity comparison of double-strength and regular-strength beclomethasone dipropionate MDI formulations

BACKGROUND

The efficacy and safety of regular-strength beclomethasone dipropionate MDI prescribed within its recommended dosing range of 2 to 5 puffs three to four times daily has been well established in more than 25 years of worldwide use. A more concentrated formulation delivering 84 microg per puff was developed to provide for a more convenient twice-daily dosing regimen.

OBJECTIVE

This randomized, single-blinded, positive and placebo-controlled, parallel-group, multiple-dose bioactivity study was conducted to assess the potential of a new beclomethasone dipropionate 84 microg double-strength metered-dose inhaler (Vanceril 84 microg Double Strength Inhalation Aerosol/Key) to cause hypothalamic-pituitary-adrenocortical axis suppression.

METHODS

Beclomethasone dipropionate double-strength 84 microg was compared with beclomethasone dipropionate regular-strength 42 microg, orally administered prednisone, and placebo inhaler after 36 consecutive days of administration in adults with moderate asthma. Beclomethasone dipropionate double-strength was administered as 5 puffs BID and beclomethasone dipropionate regular-strength was administered as 10 puffs BID for the same total daily dose of 840 microg of beclomethasone dipropionate. Oral prednisone was administered by mouth at 10 mg once a day. The potential for hypothalamic-pituitary-adrenocortical axis suppression was evaluated by an adrenocorticotropic hormone (ACTH) stimulation test using cosyntropin 250 microg in 500 mL normal saline infused over six hours on the 36th day of treatment. Sixty-four patients completed this study.

RESULTS

No clinically significant post-study findings were observed from physical examination, electrocardiogram, or clinical laboratory evaluation for any treatment group. No serious or unexpected adverse events were reported. On the 36th day of treatment, there was a significant (P < .01) difference in the plasma cortisol concentration response to cosyntropin stimulation between the prednisone and placebo treatment groups at the sixth hour of infusion. There was no significant difference in the plasma cortisol concentration response to cosyntropin stimulation between the beclomethasone dipropionate double-strength and beclomethasone dipropionate regular-strength treatment groups and the placebo group. In addition, comparison of the response between the beclomethasone dipropionate double-strength and beclomethasone dipropionate regular-strength groups showed no significant difference.

CONCLUSION

Beclomethasone dipropionate, administered either via a double-strength (84 microg/puff) or regular-strength (42 microg/puff) inhaler dosed at 840 microg/day showed no evidence of hypothalamic-pituitary-adrenocortical axis suppression in adults with moderate asthma.

Safety and tolerability of once-daily mometasone furoate aqueous nasal spray in children

Sensitive and reproducible assessments of hypothalamic-pituitary-adrenal (HPA) axis function were used to assess the systemic exposure and tolerability of mometasone furoate aqueous nasal spray (MFNS) in 96 children aged 3 to 12 years with allergic rhinitis. In the first phase of the study, older children (aged 6 to 12 years) received MFNS at 50, 100, or 200 micrograms or placebo once daily for 7 days, and plasma cortisol concentrations were measured by radioimmunoassay before and after treatment. Plasma cortisol concentrations were not statistically significantly different from baseline values on day 7 or day 8 (1 day after treatment was stopped). Also, the mean plasma cortisol and 24-hour urinary free-cortisol concentrations of the MFNS-treated and placebo groups were not statistically significantly different. Additionally, mometasone furoate was undetectable in almost all plasma samples collected at 0.5, 1, and 2 hours after dosing on days 1 and 7. Because these findings indicated that MFNS could be safely administered to patients aged 6 to 12 years, a more rigorous assessment was conducted in younger patients (aged 3 to 5 years). The younger patients also received MFNS at 50, 100, or 200 micrograms or placebo once daily, but for a longer duration (14 days). HPA axis function was determined by the response to cosyntropin stimulation on the final day of treatment. The younger patients demonstrated a normal cortisol response to cosyntropin stimulation on day 14; that is, all the patients had an increase in plasma cortisol concentration of at least 7 micrograms/dL to at least 18 micrograms/dL. Mean plasma cortisol concentrations for the MFNS-treated groups were not statistically significantly different from the mean concentration for the placebo group, either before or after cosyntropin stimulation. MFNS was also found to be well tolerated by both the younger and older children, with headache the most frequently reported adverse event in both the placebo- and MFNS-treated groups. No clinically relevant changes in the results of physical examinations, clinical laboratory determinations, or electrocardiography were noted. These results indicate that the intranasal administration of up to 200 micrograms of MFNS once daily for up to 14 days in children aged 3 to 12 years who have allergic rhinitis is well tolerated and does not result in clinically relevant systemic exposure.

Pharmacokinetics of loratadine and pseudoephedrine following single and multiple doses of once- versus twice-daily combination tablet formulations in healthy adult males

The pharmacokinetic profiles of single and multiple doses of loratadine, descarboethoxyloratadine (DCL) (the major active metabolite of loratadine), and pseudoephedrine were determined in a randomized, open-label, two-way crossover study in 24 healthy men. Subjects received a single dose (day 1) and multiple doses (days 3 to 10) of a once-daily (QD) formulation of loratadine 10 mg in an immediate-release coating and pseudoephedrine sulfate 240 mg in an extended-release core (CLAR-ITIN-D 24 HOUR tablets), and a twice-daily (BID) formulation of loratadine 5 mg in an immediate-release coating and pseudoephedrine sulfate 120 mg, with 60 mg in an immediate-release coating and 60 mg in the barrier-protected core (CLARITIN-D 12 HOUR tablets) in study sessions, each separated by a 10-day washout period. Both regimens were safe and well tolerated. On day 1, plasma loratadine, DCL, and pseudoephedrine concentrations were higher following the QD formulation than following the BID formulation, as expected. On day 10, loratadine and DCL maximum plasma concentration (Cmax) values were, on average, 87% and 35% higher, respectively, for the QD formulation than for the BID formulation; however, the values of the area under the plasma concentration-time curve from 0 to 24 hours (AUC0-24) for loratadine and DCL were equivalent (90% confidence interval [CI]: 83% to 110% for loratadine; 90% to 107% for DCL). On day 10, pseudoephedrine Cmax and AUC0-24 values were equivalent (90% CI for Cmax: 94% to 109%; for AUC: 91% to 106%) for the two formulations, and lower pseudoephedrine concentrations were observed from 16 to 24 hours with the QD formulation. Both loratadine/pseudoephedrine formulations produced equivalent loratadine and DCL AUC0-24 values and equivalent pseudoephedrine Cmax and AUC0-24 values following multiple dosing. The lower pseudoephedrine concentrations in the evening with the QD formulation may minimize the potential for insomnia in patients when compared with the BID formulation.

Single and multiple dose pharmacokinetics of felbamate in the elderly

AIMS

The objective of this study was to compare the pharmacokinetics, safety and tolerability of the antiepileptic drug felbamate in young and elderly healthy vounteers.

METHODS

The single and multiple dose pharmacokinetics of felbamate were examined in an open-label two-dose level parallel group study in 24 elderly (66 to 78-year-old) and 11 young (18 to 45-year-old) healthy volunteer subjects. Pharmacokinetics were determined from blood samples obtained over 120 h after administration of single 600 mg or 1200 mg doses, and after multiple doses of 600 mg or 1200 mg administered every 12 h. Safety and tolerability were assessed through laboratory tests, ECGs, vital signs and reported adverse events.

RESULTS

Single dose felbamate pharmacokinetic parameters differed between young and elderly subjects; compared with young subjects, elderly subjects had lower mean clearance (31.2 vs 25.1 ml min(-1); 90% CI -11.4 to -0.9; P = 0.02) and a trend towards a greater half-life (18.6 vs 21.0 h; 90% CI -0.6 to 5.4; P = 0.11). Mean AUC and C(max) values were also higher in elderly subjects. No gender differences were noted for weight-adjusted pharmacokinetic variables. Felbamate was less well tolerated in elderly subjects compared with young subjects, as shown by higher rates of adverse event reporting and dropouts at the higher dose level. This may be due to age-related pharmacokinetic differences, to the rapid dose titration schedule used in this study, and/or to altered sensitivity to felbamate's pharmacodynamic effects.

CONCLUSIONS

These findings imply that elderly subjects require lower initial dosing and slower dose titration of felbamate than non-elderly subjects.

Pharmacodynamics of subcutaneous recombinant human interleukin-10 in healthy volunteers

Interleukin-10 inhibits T-lymphocyte activation and proliferation and lipopolysaccharide-induced monocyte production of proinflammatory cytokines. Fifty-four healthy volunteers received single doses of recombinant human interleukin-10 (1.0, 2.5, 5.0, 10, 25, or 50 micrograms/kg) or placebo by subcutaneous injection (randomized double-blind assignment). Clinical adverse events were infrequent at doses below 50 micrograms/kg (five of six subjects had mild flu-like syndrome). Mean serum interleukin-10 concentrations were dose related. The mean terminal-phase half-life ranged from 2.7 to 4.5 hours, and the apparent volume of distribution ranged from 0.70 to 1.35 L/kg. Hematologic changes included transient mild to moderate increases of neutrophil counts, decreases of lymphocyte counts, and a delayed decrease of platelet counts. Recombinant human interleukin-10 significantly suppressed production of the proinflammatory cytokines interleukin-1 beta and tumor necrosis factor-alpha by whole blood stimulated ex vivo with Escherichia coli lipopolysaccharide.

Single-dose pharmacokinetics of felbamate in patients with renal dysfunction

AIMS

The purpose of this study was to evaluate the effects of renal impairment on the single-dose pharmacokinetics of the antiepileptic felbamate.

METHODS

Twelve subjects with three levels of renal dysfunction (creatinine clearance > 30-80, > 10-30 or 5-10 m min(-1)) and four controls with normal renal function (creatinine clearance > 80 ml min(-1) were studied). Plasma and urine samples were obtained for 144 h following administration of a single 1200 mg dose.

RESULTS

Compared with controls, apparent total body clearance, renal clearance and urinary excretion of felbamate were decreased, and half-life, Cmax and AUC values were increased in subjects with renal dysfunction. The magnitude of these changes was associated with the degree of renal dysfunction. Nonrenal clearance and apparent volume of distribution values were also lower in renal dysfunction subjects, but there was no association between the extent of these changes and degree of renal dysfunction. Renal clearance of felbamate accounted for approximately 30% of apparent total body clearance in the control group and from 9-22% in the renal failure patients. Renal clearance of felbamate was significantly correlated with creatinine clearance (r = 0.75; P< 0.001).

CONCLUSIONS

These data suggest that initial dosage and titration of felbamate may require adjustment in patients with renal dysfunction.

Attenuation of proinflammatory response by recombinant human IL-10 in human endotoxemia: effect of timing of recombinant human IL-10 administration

To determine the effects of IL-10 on cytokine and granulocyte responses during endotoxemia, two groups of eight healthy male volunteers were challenged with endotoxin (4 ng/kg) on two occasions, once in combination with placebo injection, and once in conjunction with i.v. administered recombinant human IL-10 (rhIL-10) (25 microg/kg). In group 1, rhIL-10 was administered 2 min before endotoxin challenge; in group 2, the intervention was delayed for 1 h after endotoxin administration. rhIL-10 pretreatment reduced the LPS-induced rises in temperature and release of TNF, IL-6, IL-8, and IL-1 receptor antagonist. Endotoxin-induced granulocyte accumulation in lungs, as determined by dynamic granuloscintigrams, was prevented by rhIL-10 pretreatment, whereas granulocyte recruitment in liver and spleen was only modestly reduced. In addition, granulocyte degranulation, as measured by plasma elastase/alpha1-antitrypsin complexes, was blunted significantly by rhIL-10 pretreatment. Post-treatment with rhIL-10 did not influence LPS-induced temperature responses, cytokine release, or granulocyte degranulation. Both rhIL-10 pretreatment and post-treatment reduced LPS-induced cortisol levels. These results indicate that pretreatment with rhIL-10 reduces endotoxin-induced febrile responses, cytokine responses, and granulocyte accumulation in lungs, while in this acute model post-treatment with rhIL-10 exerts limited anti-inflammatory effects.

Interleukin-10 inhibits activation of coagulation and fibrinolysis during human endotoxemia

Interleukin-10 (IL-10) has been found to inhibit lipopolysaccharide (LPS)-induced tissue factor expression by monocytes in vitro. To determine the effects of IL-10 on LPS-induced activation of the hemostatic mechanisms in vivo, we performed a placebo-controlled, cross-over study of human endotoxemia. Two groups of eight volunteers were challenged with LPS (4 ng/kg) on two occasions: once in conjunction with placebo, and once with recombinant human IL-10 (rhIL-10; 25 microg/kg). In group 1, placebo or rhIL-10 was given 2 minutes before LPS challenge, group 2 received placebo or rhIL-10 1 hour after LPS administration. Pretreatment with rhIL-10 reduced both LPS-induced activation of the fibrinolytic system (plasma concentrations of tissue type plasminogen activator, plasmin-alpha2-antiplasmin complexes, and D-dimer), and inhibition of fibrinolysis (plasma levels of plasminogen activator inhibitor 1), whereas posttreatment only inhibited the latter response. Both IL-10 pre- and posttreatment attenuated activation of the coagulation system (plasma levels of prothrombin fragment F1 + 2 and thrombin-antithrombin complexes). These results indicate that rhIL-10, besides its well-described inhibitory effects on cytokine release, potently modulates the fibrinolytic system and inhibits the coagulant responses during endotoxemia.

Attenuation of proinflammatory response by recombinant human IL-10 in human endotoxemia: effect of timing of recombinant human IL-10 administration

To determine the effects of IL-10 on cytokine and granulocyte responses during endotoxemia, two groups of eight healthy male volunteers were challenged with endotoxin (4 ng/kg) on two occasions, once in combination with placebo injection, and once in conjunction with i.v. administered recombinant human IL-10 (rhIL-10) (25 microg/kg). In group 1, rhIL-10 was administered 2 min before endotoxin challenge; in group 2, the intervention was delayed for 1 h after endotoxin administration. rhIL-10 pretreatment reduced the LPS-induced rises in temperature and release of TNF, IL-6, IL-8, and IL-1 receptor antagonist. Endotoxin-induced granulocyte accumulation in lungs, as determined by dynamic granuloscintigrams, was prevented by rhIL-10 pretreatment, whereas granulocyte recruitment in liver and spleen was only modestly reduced. In addition, granulocyte degranulation, as measured by plasma elastase/alpha1-antitrypsin complexes, was blunted significantly by rhIL-10 pretreatment. Post-treatment with rhIL-10 did not influence LPS-induced temperature responses, cytokine release, or granulocyte degranulation. Both rhIL-10 pretreatment and post-treatment reduced LPS-induced cortisol levels. These results indicate that pretreatment with rhIL-10 reduces endotoxin-induced febrile responses, cytokine responses, and granulocyte accumulation in lungs, while in this acute model post-treatment with rhIL-10 exerts limited anti-inflammatory effects.

Comparative pharmacokinetics of oral ceftibuten, cefixime, cefaclor, and cefuroxime axetil in healthy volunteers

STUDY OBJECTIVE

To compare the pharmacokinetics of ceftibuten, cefixime, ceturoxime axetil, and cefaclor after oral administration.

DESIGN

Randomized, four-period, crossover study.

SETTING

Hospital-based clinical research center.

SUBJECTS

Healthy adult men and women volunteers.

INTERVENTIONS

Single 400-mg doses of cefixime and ceftibuten, and 500-mg doses of cefuroxime axetil and cefaclor.

MEASUREMENTS AND MAIN RESULTS

Serum concentrations were determined by high-performance liquid chromatography methods. The mean oral clearances of cefixime, cefuroxime axetil, and cefaclor were similar, ranging from 20.4-27.0 L/hour; clearance of ceftibuten was approximately 4-fold less, 5.45 L/hour. The serum half-lives of ceftibuten (2.35 hrs) and cefixime (2.38 hrs) were prolonged compared with those of cefuroxime axetil (1.30 hrs) and cefaclor (0.693 hr). These agents also differed in terms of time to maximum concentration, time to peak plasma level, area under the curve, and apparent volume of distribution, the last reflecting differences in biovailability.

CONCLUSION

Ceftibuten had a relatively high time to maximum concentration and long half-life, resulting in a 3.5-fold higher area under the curve than cefixime, cefuroxime axetil, and cefaclor. These pharmacokinetic data can be used as a basis to compare the four oral cephalosporins; however, comparative susceptibility data must also be considered.

Influence of food on the oral bioavailability of loratadine and pseudoephedrine from extended-release tablets in healthy volunteers

The effect of a high-fat breakfast on the bioavailability of the components of an extended-release tablet containing 10 mg loratadine in the immediate-release coating and 240 mg pseudoephedrine sulfate in the extended-release core was studied in 24 healthy male volunteers in a single-dose, two-way crossover study. The drug was administered after a 10-hour overnight fast or within 5 minutes of consuming a standardized high-fat breakfast. Serial blood samples were collected over a 48-hour period, and plasma was analyzed for loratadine and its active metabolite descarboethoxyloratadine (DCL), and pseudoephedrine. For pseudoephedrine, maximum concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUCzero-infinity) were similar after both treatments, indicating no relevant food effect on the bioavailability of pseudoephedrine. Also, the absorption profiles of pseudoephedrine (from Wagner-Nelson analysis) were similar for the fed and fasted treatments, indicating no apparent differences in absorption. Plasma concentration-time profiles and values for Cmax and AUCzero-infinity of DCL were similar for the two treatments, indicating no relevant food effect on the pharmacokinetics of DCL. In contrast, for loratadine, administration with food resulted in a significantly increased mean Cmax (53%) and AUC from time zero to the final quantifiable sample (AUCif) (76%). However, the resultant Cmax and AUC of loratadine under fed conditions were well below those previously obtained at steady-state after multiple-dose administration of loratadine (40 mg/day) that were shown to be safe and well-tolerated in several clinical studies. The effect of food on the bioavailability and pharmacokinetic profiles of the components of a combination loratadine/pseudoephedrine extended-release tablet is not likely to be clinically significant.

Clinical, hematologic, and immunologic effects of interleukin-10 in humans

We conducted a double-blind, placebo-controlled study to investigate the safety, pharmacokinetics, and immunological properties of interleukin-10 (IL-10) administration in healthy humans. Volunteers received a single intravenous bolus injection of recombinant human IL-10 (1, 10, or 25 micrograms/kg) or placebo. Cytokine production in whole blood and peripheral blood mononuclear cells (PBMC) was assessed before and 3, 6, 24, and 48 hr after the injection. Peak serum concentrations of IL-10 (15 +/- 1.1, 208 +/- 20.1, and 505 +/- 22.3 ng/ml) occurred after 2-5 min for 1, 10, and 25 micrograms/kg IL-10, respectively. The terminal-phase half-life was 3.18 hr. A transient leukocytosis (24-63% above baseline) was observed 6 hr after injection, which coincided with a dose-dependent decrease (12-24%) in neutrophil superoxide generation. There was a marked inhibition (60-95%) of endotoxin-induced IL-6 production from whole blood in each group receiving IL-10. Production of IL-8 in endotoxin-stimulated blood was reduced in the 10 micrograms/kg group. In PBMC stimulated with phytohemagglutinin and phorbol ester, there was a decrease (72-87%) in interferon-gamma (IFN gamma) production 6 hr after IL-10 with a return to pre-IL-10 levels after 24 hr. This reduction was only partially associated with a decrease in the number of CD2-bearing cells. We conclude that IL-10 administration into humans is without significant side effects, and a single injection reduces ex vivo production of IL-6, IL-8, and IFN gamma.

Effect of felbamate on the pharmacokinetics of lamotrigine

To assess the possible interaction between lamotrigine and felbamate, a double-blind, randomized, placebo-controlled, two-way crossover study was conducted in 21 healthy male volunteers. Volunteers were given lamotrigine (100 mg every 12 hours) and felbamate (1,200 mg every 12 hours) or matching placebo for 10 days during each period of the crossover. After morning administration on day 10, blood samples were obtained over 12 hours for measurement of lamotrigine. Felbamate increased the maximum concentration (Cmax) and and area under the concentration-time curve from time 0 to 12 hours (AUC0-12) of lamotrigine by 13% and 14%, respectively, compared with placebo. The 90% confidence intervals of the log-transformed pharmacokinetic parameters were within the 80-125% bioequivalance limits, however. Felbamate had no significant effect on the urinary excretion of lamotrigine (total), unconjugated lamotrigine, or the N-glucuronide. One volunteer discontinued the study after developing a rash while taking lamotrigine and placebo. All other adverse events were primarily related to the central nervous system and gastrointestinal tract, with a higher incidence reported during coadministration of lamotrigine and felbamate than with placebo. Overall, felbamate appears to have no clinically relevant effects on the pharmacokinetics of lamotrigine.

The effect of age on the apparent clearance of felbamate: a retrospective analysis using nonlinear mixed-effects modeling

The effects of age on felbamate apparent clearance were examined through a retrospective analysis of plasma concentration data from 700 pediatric and adult epileptic patients (age range, 2-74 years) enrolled in six clinical studies. Patients received felbamate as monotherapy or in combination with either the antiepileptic drugs (AEDs) carbamazepine (CBZ), phenytoin (PHT), or valproate (VPA). Data were analyzed using a nonlinear mixed-effects pharmacostatistical modeling technique (NONMEM). Factors in the model included age, body weight, and concomitant AEDs. Apparent clearance was highest in the very young and decreased during the early teenage years, with minimal changes observed beyond 13 years. Mean apparent clearance values were approximately 40% higher in children (2-12 years) compared with those in adults (13-65 years). This pattern and its magnitude were consistent whether felbamate was administered alone or coadministered with CBZ, PHT, or VPA. The increase in clearance is minimal compared with other AEDs including PHT, CBZ, and phenobarbital. Enzyme-inducing AEDs (CBZ and PHT) increased felbamate apparent clearance by 32-38% relative to monotherapy, whereas coadministration with VPA had a minimal effect on felbamate apparent clearance. Dose/concentration linearity was observed at all ages during mono- or polytherapy. These findings suggest that felbamate dosing should be relatively uncomplicated in children relative to that in adults.

Pharmacokinetics and immunomodulatory properties of intravenously administered recombinant human interleukin-10 in healthy volunteers

Normal volunteers received single doses of recombinant human interleukin-10 (rhIL-10; n = 6 per group) or placebo (n = 3 per group) by intravenous injection to characterize pharmacokinetics, tolerability, and immunomodulatory effects. Dosages were 0.1, 0.5, 1.0, 2.5, 5.0, 10.0, 25.0, 50.0, and 100.0 micrograms/kg. Dose-related adverse effects consisted of a mild-to-moderate flu-like syndrome characterized by fever with chills, headache, and myalgias at the highest dose. The mean terminal phase t1/2 ranged from 2.3 +/- 0.5 to 3.7 +/- 0.8 hours. Dose-related effects of rhIL-10 included transient increases of circulating neutrophils and monocytes and decreases of lymphocytes. rhIL-10 markedly suppressed, in a time- and dose-dependent manner, the synthesis of the inflammatory cytokines IL-1 beta and tumor necrosis factor alpha by whole blood stimulated ex vivo with bacterial lipopolysaccharide. Circulating numbers of CD14+/HLA-DR+ cells at 24 hours after the dose were increased in a dose-dependent manner. Effects on expression of HLA-DR by CD14+ cells were variable. There was no apparent effect on HLA-DR expression by CD20+ cells. The immunomodulatory effects of rhIL-10 merit further clinical investigation.

Loratadine administered concomitantly with erythromycin: pharmacokinetic and electrocardiographic evaluations

OBJECTIVE

To evaluate the effects of coadministration of loratadine and erythromycin on the pharmacokinetics and electrocardiographic repolarization (QTc) pharmacodynamics of loratadine and its metabolite descarboethoxyloratadine in healthy volunteers.

METHODS

Twenty-four healthy volunteers were studied in a prospective, double-blind crossover design while confined in a Clinical Research Center. The primary pharmacodynamic end point of the study was the difference between baseline and day 10 mean QTc intervals obtained from surface electrocardiograms. Plasma concentrations of loratadine, descarboethoxyloratadine, and erythromycin were measured on treatment day 10 for pharmacokinetic analysis. Subjects received in random sequence the following three treatments for 10 consecutive days during three separate study periods: 10 mg loratadine every morning plus 500 mg erythromycin stearate every 8 hours, or 10 mg loratadine every morning plus placebo every 8 hours, or placebo every morning plus 500 mg erythromycin stearate.

RESULTS

Concomitant administration of loratadine and erythromycin was associated with increased plasma concentrations of loratadine (40% increase in area under the plasma concentration-time curve [AUC]) and descarboethoxyloratadine (46% increase in AUC) compared with loratadine alone. Analysis of variance showed no difference between the treatment groups in effect on QTc intervals compared with baseline, and no significant change from baseline was observed. No clinically relevant changes in the safety profile of loratadine were observed, and there were no reports of sedation nor syncope.

CONCLUSION

Although concomitant administration of loratadine and erythromycin was associated with increased plasma concentrations of loratadine and descarboethoxyloratadine, no clinically relevant changes in the safety profile of loratadine were observed. In this study, 10 mg loratadine administered orally for 10 consecutive days was well tolerated when coadministered with therapeutic doses of erythromycin stearate.

Biopharmaceutic characteristics of a new extended-release theophylline formulation (Uni-Dur)

BACKGROUND

There is a close relationship between improvement in airway function and the plasma concentration of theophylline, as well as between rapidly rising plasma theophylline concentrations and increased frequency of undesired effects. Development of pharmaceutical formulations and prescribed dosage intervals for theophylline dosage forms should therefore be directed toward providing the most stable plasma concentrations attainable.

OBJECTIVE

To characterize the steady-state biopharmaceutic profile of Uni-Dur following once-daily or twice-daily administration.

METHODS

Twenty-four adult male volunteers with average theophylline clearance (3.0 and 5.5 L.h-1) received three treatments on separate occasions: Uni-Dur 800 mg once-daily, Uni-Dur 400 mg twice-daily, and Uniphyl 800 mg once-daily. Treatments were taken after a meal for five days with at least 1 week washout between treatment periods. Trough blood samples were collected prior to the AM dose on days 3, 4, and 5, and at specified intervals up to 48 hours after the AM dose on day 5 for subsequent determination of theophylline concentrations in plasma.

RESULTS

The area under the plasma concentration-time curve (AUC; microgram.mL-1.h) for theophylline over 24 hours on day 5 was 187 for Uni-Dur 800 mg once-daily, 187 for Uni-Dur 400 mg twice-daily, and 172 for Uniphyl 800 mg once-daily; the peak plasma concentrations were 10.4, 9.4, and 11.0 micrograms.mL-1 and the trough concentrations were 5.5, 7.2, and 3.5 micrograms.mL-1, respectively; fluctuation index (peak minus trough divided by trough) was 78%, 16%, and 231%, respectively. No further accumulation of theophylline occurred after day 3. No serious nor severe adverse events were reported during any treatment.

CONCLUSIONS

Uni-Dur is an extended-release formulation that provides stable plasma concentrations of theophylline over a 24-hour period with less fluctuation than observed with a once-daily reference formulation. In subjects with normal theophylline clearance, Uni-Dur administered twice-daily provided remarkably stable theophylline plasma concentrations over a 24-hour period. Absorption of theophylline from Uni-Dur was not affected by food, and no evidence of dose-dumping was observed. Uni-Dur should provide efficacious theophylline therapy with minimal adverse events in patients with symptoms of asthma and reversible bronchospasm associated with chronic bronchitis and emphysema.

Lack of hypothalamic-pituitary-adrenal axis suppression with once-daily or twice-daily beclomethasone dipropionate aqueous nasal spray administered to patients with allergic rhinitis

The potential for a newly developed, double-strength (0.084%) beclomethasone dipropionate (BDP) aqueous (AQ) nasal suspension to produce effects associated with exposure to systemic corticosteroids was assessed by the plasma cortisol response to cosyntropin stimulation induced by a 6-hour intravenous infusion of 250 micrograms of cosyntropin in 500 mL of normal saline. Sixty-four patients with allergic rhinitis were enrolled in this study. Patients were randomly assigned to one of the following four treatment groups: (1) BDP AQ Forte (0.084%) nasal spray 336 micrograms once daily; (2) BDP AQ (0.042%) nasal spray 168 micrograms twice daily; (3) placebo nasal spray twice daily; or (4) oral prednisone 10 mg once daily in the morning. After 36 consecutive days of treatment, there was a significant (P < 0.01) difference in the plasma cortisol response to cosyntropin stimulation between the prednisone and placebo groups; however, there were no significant differences between the BDP AQ Forte or the BDP AQ groups compared with the placebo group. Secondary analyses comparing BDP AQ Forte administered as 336 micrograms once daily with BDP AQ administered as 168 micrograms twice daily showed no significant differences in plasma cortisol responses to cosyntropin stimulation. No serious adverse events were reported. Adverse events consisted of headache, pharyngitis, or nasal irritation, with headache being reported most frequently. These adverse events were similarly distributed among active treatment groups and were similar to placebo. No clinically relevant changes were observed in any treatment group in findings on clinical laboratory tests, physical examination, or electrocardiography. Vital signs, obtained daily, were consistent with values observed in healthy individuals. No patient exhibited signs of oral candidiasis. All patients met the plasma cortisol concentration criteria for discharge relative to expected hypothalamic-pituitary-adrenal axis function. In conclusion, there were no significant differences in plasma cortisol responses to cosyntropin stimulation between groups of patients with allergic rhinitis treated with either BDP AQ Forte (0.084%) nasal spray 336 micrograms once daily or BDP AQ (0.042%) nasal spray 168 micrograms twice daily compared with the placebo group. These results indicate that the dosing regimens of BDP AQ nasal suspensions used in this study lack systemic effects and are safe and well tolerated.

Pharmacokinetics of isepamicin

Isepamicin is a new aminoglycoside that has activity against many bacteria resistant to other aminoglycosides. The pharmacokinetics of isepamicin have been characterized in neonatal, pediatric, adult, elderly and renally impaired human populations as well as in clinical trials using the techniques of population pharmacokinetics. The pharmacokinetics of isepamicin are uncomplicated and generally similar to those of other aminoglycosides, although there is some evidence that it may have less tissue accumulation. The drug is completely absorbed following intramuscular administration. The drug is not metabolized and unchanged isepamicin accounts for all of the drug substance in plasma and urine. It is completely eliminated via the renal route; consequently dosing in patients with renal insufficiency has to be adjusted according to the degree of renal impairment. The pharmacokinetics of isepamicin are generally linear. Thus peak plasma concentrations and area under the plasma concentration curve (AUC) values are proportional to the administered dose while clearance (1.1-1.3 mL/min/kg), volume of distribution at steady state (0.23-0.29 L/kg) and half-life (2-2.5 h) are independent of dose. There is no significant accumulation of drug in the plasma with once- or twice-daily dosing. The isepamicin plasma concentration curve following a 1 g intravenous dose to healthy volunteers can be best characterized by a tri-exponential curve corresponding to a t1/2 alpha of 0.17 h, a t1/2 beta of 2.1 h, and a gamma-phase of 34 h. The t1/2 beta represents the elimination phase and changes with age and renal functions, while the gamma-phase represents the return of drug to plasma from a deep compartment including binding in renal tissue. The gamma-phase represents less than 3% of the total AUC and does not change with age. Isepamicin readily distributes to extracellular fluid and pulmonary tissue. In conclusion, isepamicin demonstrates predictable linear kinetics and is similar pharmacokinetically to other aminoglycosides. Preliminary indications of decreased tissue accumulation implied from pharmacokinetic and pharmacodynamic characteristics of isepamicin favour once-daily dosing.

Pharmacokinetics of isosorbide-5-mononitrate after oral administration of an extended-release mononitrate formulation versus a standard dinitrate formulation

The steady-state pharmacokinetic profile of isosorbide-5-mononitrate (5-ISMN) after oral administration of an extended-release tablet formulation of 5-ISMN 60 mg or 120 mg once a day was compared with that after administration of isosorbide dinitrate (ISDN) 40 mg every 6 hours, in a randomized, open-label, three-way crossover trial in 24 healthy men. After oral administration of extended-release 5-ISMN 60 mg or 120 mg once daily, 5-ISMN was slowly absorbed, reaching mean peak plasma concentrations of 557 and 1151 ng/mL, respectively, in approximately 3 hours. Plasma concentrations of 5-ISMN were dose proportional between 60 mg and 120 mg. After oral administration of ISDN 40 mg every 6 hours, a mean peak plasma 5-ISMN concentration of 806 ng/mL was achieved in less than 2 hours (mean time to reach the maximum plasma concentration was 1.5 hours). The mean plasma apparent elimination half-life of 5-ISMN was 6.2 hours after extended-release 5-ISMN administration and 7.1 hours after ISDN. Although the maximum plasma concentration was higher and the minimum plasma concentration was lower after administration of extended-release 5-ISMN 120 mg once daily compared with ISDN 40 mg every 6 hours, there was no significant difference (P > 0.05) in the "bioavailability" of 5-ISMN between these two treatments. The most commonly reported adverse events in these "nitrate-naive" subjects were headache, dizziness, nausea, and vomiting; these were dose related and their incidence decreased with repeated exposure.

Effect of food on the oral bioavailability of isosorbide-5-mononitrate administered as an extended-release tablet

We evaluated the effect of a high-fat breakfast and gastric emptying rate on the oral bioavailability of a isosoribide-5-mononitrate (5-ISMN) controlled-release tablet formulation (IMDUR 60-mg tablets, Astra Hässle AB, Mölndal, Sweden) relative to an oral solution in 18 healthy men. Gastric emptying was monitored by radiotelemetry using the Heidelberg capsule technique. After administration of the 5-ISMN 60-mg solution, absorption was rapid with mean peak plasma 5-ISMN concentrations of 1533 ng/mL achieved in less than 1 hour. In contrast, after administration of IMDUR 60-mg tablets, the drug was more slowly absorbed, reaching mean peak plasma concentrations of 541 ng/mL in 3 to 4 hours. The bioavailability of 5-ISMN from IMDUR tablets under fasted conditions was approximately 78% relative to the solution; and, in the presence of food, the bioavailability was slightly increased to 86% (P = .057). The mean gastric residence time of IMDUR tablets under fasted conditions was 68 minutes, and in the presence of food was increased to 478 minutes, with 9 of the 18 subjects having gastric emptying delayed for at least 600 minutes. We conclude that in the presence of food, gastric emptying time is considerably increased causing a delay in drug absorption and a slight increase in the bioavailability of 5-ISMN from this controlled-release tablet formulation, however this effect is not clinically relevant.

Pharmacokinetics of the triazole antifungal agent genaconazole in healthy men after oral and intravenous administration

The pharmacokinetics of genaconazole, a potent new difluorophenyl-triazole antifungal agent, was studied in 12 healthy male volunteers following a single oral or intravenous administration of the drug. In a randomized two-way crossover design, each volunteer received either two 50-mg genaconazole tablets orally or a parenteral preparation containing 100 mg of genaconazole given as a 30-min intravenous infusion. Both dosage regimens were well tolerated. Blood and urine samples were collected up to 10 days after drug administration. Concentrations of genaconazole in plasma and urine were determined by a specific high-performance liquid chromatography assay with a limit of quantitation of 0.1 microgram/ml. Pharmacokinetic evaluation following oral and intravenous doses indicated that mean values for the area under the concentration-time curve from 0 h to infinity (137 and 136 micrograms.h/ml), half-life (50 and 49 h), volume of distribution (52 and 52 liters), and clearance (12 and 12 ml/min) were independent of the route of drug administration. The oral and intravenous administrations of genaconazole yielded virtually superimposable plasma concentration-time curves, resulting in an absolute bioavailability of 100%. Amounts of unchanged genaconazole found in urine samples from 0 to 240 h after oral and intravenous doses were comparable, and urinary excretion accounted for 76 and 78% of the administered dose, respectively. Renal clearances for the two routes of administration were also similar, and renal clearance accounted for over 80% of the total body clearance. The 100% absolute bioavailability of genaconazole regardless of the route of administration provides greater dosing flexibility in various clinical settings than currently exists.

Effects of caffeine or ethanol on treadmill performance and metabolic responses of well-trained men

The effects of caffeine and ethanol on treadmill performance and metabolic responses to exercise were determined in four trained runners. Caffeine (2.5 mg.kg-1 body weight) or ethanol (25 ml) in 150 ml of grapefruit juice (total volume) or grapefruit juice (placebo) was randomly administered 10 minutes prior to and at 30 minutes of a 60 minutes treadmill run. The speed and grade of the treadmill was adjusted to elicit an average oxygen consumption of 80-85% of the subject's maximal oxygen consumption. All subjects completed the treadmill run for the caffeine and placebo conditions. Three of the four subjects could not complete the treadmill run following the second administration of ethanol. Exercise heart rate was significantly greater for the ethanol condition than for the placebo condition. Exercise oxygen consumption was greater following ethanol administration than for placebo, but the differences were not significant. Blood glucose rose significantly between 0 and 30 minutes of treadmill running for all three conditions. Between 30 minutes of treadmill running and either 60 minutes or the time of termination of the exercise, blood glucose decreased significantly by 24% following the second ethanol treatment. Plasma fatty acid, triglyceride, creatine phosphokinase, and renin contents followed expected exercise changes with a blunting of the rise of plasma fatty acids at 30 minutes of exercise for the ethanol condition. It was concluded that the administration of ethanol adversely influenced treadmill exercise performance by eliciting a hypoglycemic effect between 30 minutes and the termination of the exercise.

Effect of ethanol on metabolic responses to treadmill running in well-trained men

The metabolic effects of ethanol on treadmill performance were determined in four trained runners. Ethanol in doses of 25 mL in 150 mL of grapefruit juice (total volume) or grapefruit juice was randomly administered 10 minutes before and at 30 minutes of a 60-minute treadmill run. The speed and grade of the treadmill was adjusted to elicit an average oxygen consumption (VO2) of 80 to 85% of the subjects' VO2max. Three of the four subjects could not complete the treadmill run after the administration of ethanol. Administration of ethanol resulted in significant increases in the heart rate responses to treadmill running above those for the placebo grapefruit treatment. VO2 was higher after ethanol administration than the placebo grapefruit juice treatment, but these values were not significant. Blood glucose content rose significantly between 0 and 30 minutes of treadmill running for both the ethanol and placebo grapefruit juice treatments. Between 30 minutes of treadmill running and the termination of the exercise, the blood glucose level decreased significantly by 24% after the second ethanol treatment at 30 minutes of exercise. Plasma fatty acid, triglyceride, creatine phosphokinase, and renin contents followed expected exercise changes. It was concluded that the administration of ethanol adversely influenced treadmill exercise performance by eliciting a hypoglycemic effect between 30 minutes and the termination of the exercise.

Effect of concomitant administration of piperacillin on the dispositions of isepamicin and gentamicin in patients with end-stage renal disease

Piperacillin inactivation of the aminoglycosides isepamicin and gentamicin in 12 chronic hemodialysis patients was assessed. Six subjects each received isepamicin (7.5 mg/kg of body weight) or gentamicin (2 mg/kg) alone and in combination with piperacillin (4 g every 12 h for four doses). Isepamicin and gentamicin concentrations in plasma and urine were monitored over 48 h after each dose and analyzed by high-performance liquid chromatography and fluorescence polarization immunoassay, respectively. The pharmacokinetics of isepamicin were not significantly altered during combination treatment with piperacillin. The total body clearance (3.79 +/- 0.71 versus 3.94 +/- 1.05 ml/min), the steady-state volume of distribution (0.19 +/- 0.04 versus 0.18 +/- 0.03 liter/kg), and the terminal elimination half-life (47.91 +/- 7.20 versus 45.08 +/- 10.34 h) were not significantly altered in the presence of piperacillin. In contrast, the terminal elimination half-life (47.68 +/- 20.58 versus 35.67 +/- 11.18 h) of gentamicin was significantly reduced when gentamicin was given with piperacillin. The total body clearance (4.26 +/- 3.07 versus 4.89 +/- 1.94 ml/min) and the steady-state volume of distribution (0.19 +/- 0.04 versus 0.20 +/- 0.04 liter/kg) of gentamicin were not significantly altered during combination therapy; however, the nonrenal clearance of gentamicin administered in combination with piperacillin (3.56 +/- 0.38 ml/min) increased significantly compared with that of gentamicin (2.03 +/- 0.50 ml/min) given alone. The results of this study suggest that no additional dosage adjustment of isepamicin during concomitant therapy with piperacillin in hemodialysis patients is necessary. However, this does not preclude the need for appropriately ex vivo-handled specimens for monitoring isepamicin concentrations in plasma to ensure therapeutic efficacy and prevent toxicity. Furthermore, additional dosage adjustments may be necessary when gentamicin is used concomitantly with piperacillin, on the basis of the significant in vivo inactivation that takes place in end-stage renal disease patients.

Differential plasma duration of antiplatelet-activating factor and antihistamine activities of oral Sch 37370 in humans

Preclinical studies have established that Sch 37370 (1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]-cyclohepta [1,2-b]pyridin-11-ylidene)piperidine) is an orally active antagonist of platelet-activating factor (PAF) and histamine H1-receptors with potential therapeutic use in the treatment of asthma. To evaluate the efficacy and duration of anti-PAF and antihistamine actions of oral Sch 37370 in humans, a single dose (5 mg/kg) of Sch 37370 was given orally to each of 10 male subjects in a placebo-controlled, double-blind crossover study. Blood samples were drawn before and at various times (2 to 48 hours) after Sch 37370 or placebo. Plasma samples were analyzed for Sch 37370 by a gas chromatographic method, for the anti-PAF activity by measuring the aggregation of platelets stimulated with PAF, and for the antihistamine activity by measuring displacement of [3H]pyrilamine from rat brain membrane binding sites. The plasma anti-PAF activity declined from high levels at 2 hours to barely detectable levels at 24 hours; however, significant activity was still present at 12 hours. The plasma levels of Sch 37370 closely paralleled the anti-PAF profile. The plasma antihistamine activity reached a maximum within 2 to 8 hours and declined thereafter. However, 48 hours after Sch 37370, the antihistamine activity was still present at a significant level in most subjects. It is concluded that, in humans, oral Sch 37370 antagonizes both PAF and histamine with plasma antihistamine activity lasting longer than plasma anti-PAF activity.

Isepamicin disposition in subjects with various degrees of renal function

The disposition of isepamicin, an investigational aminoglycoside antibiotic, was evaluated in 30 subjects with various degrees of renal function. The subjects were divided into five groups: those with normal renal function (creatinine clearance [CLCR], greater than 80 ml/min/1.73 m2), those with mild renal insufficiency (CLCR, 50 to 80 ml/min/1.73 m2), those with moderate renal insufficiency (CLCR, 30 to 49 ml/min/1.73 m2), those with severe renal insufficiency (CLCR, 5 to 29 ml/min/1.73 m2), and those maintained on hemodialysis (CLCR, less than 5 ml/min/1.73 m2). Subjects on hemodialysis were studied both during hemodialysis and during an interdialytic period. The volumes of distribution of isepamicin were not significantly different among the five groups of patients. The total body clearance (CLP) and renal clearance (CLR) of isepamicin significantly decreased as CLCR decreased. The CLP of isepamicin and CLCR were significantly related [(COP = 0.391.[CLCR] + 1.83; r2 = 0.878)]. Nonrenal clearance of isepamicin did not differ between groups. Hemodialysis augmented the CLP of isepamicin by approximately 25-fold. The amount of isepamicin recovered in the dialysate was 60.6 +/- 15.8% of the dose administered. The maximal rebound of the isepamicin concentration in plasma after cessation of hemodialysis was observed at 0.78 +/- 0.7 h. Concentrations in plasma increased 32.7 +/- 22.9% over that measured at the end of hemodialysis. These data indicate that dosage adjustments are necessary in subjects with decreased renal function.

Pharmacokinetics of ceftibuten-cis and its trans metabolite in healthy volunteers and in patients with chronic renal insufficiency

The impact of renal insufficiency on the dispositions of 300 mg of orally administered ceftibuten-cis, a new broad-spectrum oral cephalosporin, and its primary metabolite ceftibuten-trans was characterized in 30 adult subjects. Subjects were divided into five groups of six subjects each on the basis of their 24-h ambulatory creatinine clearances (CLCR). The apparent total body clearance (CLP/F; where F is absolute bioavailability) and renal clearance of ceftibuten-cis were significantly lower in subjects with end-stage renal disease (on maintenance hemodialysis; group V) and in those with severe (CLCR, 5 to 29 ml/min; group IV) and moderate (CLCR, 30 to 49 ml/min; group III) renal insufficiency than in those with mild renal insufficiency (CLCR, 50 to 80 ml/min; group II) or normal renal function (CLCR, greater than 80 ml/min; group I). A significant correlation was observed between CLCR and ceftibuten-cis CLP/F. The mean apparent steady-state volume of distribution (V beta/F) of ceftibuten-cis ranged from 0.21 to 0.24 liter/kg in subjects in group I, II, III, and IV. V beta/F was significantly greater in the group V subjects with end-stage renal disease (V beta/F, 0.39 +/- 0.27 liters/kg). These changes in V beta/F cannot be separated from possible changes in bioavailability. The maximum concentration of ceftibuten-trans in plasma was significantly higher and occurred significantly later in group IV subjects than it did in subjects in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Stepwise determination of multicompartment disposition and absorption parameters from extravascular concentration-time data. Application to mesoridazine, flurbiprofen, flunarizine, labetalol, and diazepam

When disposition is monoexponential, extravascular concentration-time (C, t) data yield both disposition and absorption parameters, the latter via the Wagner-Nelson method or deconvolution which are equivalent. Classically, when disposition is multiexponential, disposition parameters are obtained from intravenous administration and absorption data are obtained from extravascular C, t data via the Loo-Riegelman or Exact Loo-Riegelman methods or via deconvolution. Thus, in multiexponential disposition one assumes no intrasubject variation in disposition, a hypothesis that has not been proven for most drugs. Based on the classical two- and three-compartment open models with central compartment elimination, and using postabsorptive extravascular C, t data only, we have developed four equations to estimate k10 when disposition is biexponential and two other equations to estimate k10 when disposition is triexponential. The other disposition rate constants are readily obtained without intravenous data. We have analyzed extravascular data of flurbiprofen (12 sets), mesoridazine (20 sets), flunarizine (5 sets), labetalol (9 sets), and diazepam (4 sets). In the case of diazepam intravenous C, t data were also available for analysis. After disposition parameters had been estimated from the extravascular data the Exact Loo-Riegelman method with the Proost modification was applied to the absorptive extravascular data to obtain AT/VP as a function of time. These latter data for each subject and each drug studied were found to be fitted by a function indicating either simple first-order absorption, two consecutive first-order processes, or zero-order absorption. After absorption and disposition parameters had been estimated, for each set of extravascular data analyzed, a reconstruction trend line through the original C, t data was made. The new methods allow testing of the hypothesis of constancy of disposition with any given drug. There is also a need for new methods of analysis since the majority of drugs have no marketed intravenous formulation, hence the classical methods cannot be applied.

The effect of antacid and cimetidine on the oral absorption of the antifungal agent SCH 39304

The single-dose pharmacokinetics of the antifungal agent SCH 39304 (Schering-Plough Corp., Kenilworth, NJ) were assessed alone and in combination with antacid and cimetidine. On three separate occasions nine healthy men received a single oral 50 mg dose of SCH 39304 either alone, with 60 mL antacid, or with oral cimetidine 300 mg four times a day for 4 days. Concomitant antacid or cimetidine administration had no significant effect on any of the SCH 39304 pharmacokinetic parameters studied. The oral absorption of SCH 39304, as assessed by the area under the plasma concentration-time curve (AUC) and the amount of drug recovered unchanged in the urine, was not affected by either antacid or cimetidine. The AUC0-1 for the drug given alone was 80.5 +/- 15.8 micrograms.hr/mL, compared to 81.4 +/- 12.7 and 79.7 +/- 9.6 micrograms.hr/mL with concomitant antacid and cimetidine, respectively. The amount of drug excreted in the urine (Ae0-1) was 22.7 +/- 5.1, 24.2 +/- 9.2, and 23.6 +/- 7.6 mg when the drug was given alone, with antacid, and with cimetidine, respectively. Antacid coadministration delayed absorption as evidenced by an increase in the tmax in 7 out of 9 subjects, although this did not reach statistical significance (P = .082, Wilcoxon test). We conclude that concomitant antacid or cimetidine does not alter the oral absorption or pharmacokinetic disposition of single-dose SCH 39304.

Pharmacokinetics and pharmacodynamics of dilevalol

The pharmacokinetics and pharmacodynamics of dilevalol, the R,R stereoisomer of labetalol, were evaluated in nine subjects. Dilevalol was given as a single 50 mg intravenous dose and as a 400 mg daily oral dose for 7 days. To study the effects of hepatic enzyme inhibition, each subject received dilevalol in the presence of and absence of cimetidine. Cardiac beta-blockade was assessed by use of standardized treadmill tests for 48 hours after oral dilevalol. The three-compartment model analysis showed that systemic clearance (29.8 +/- 5.7 ml/min/kg), volume of distribution (16.6 +/- 4.1 L/kg), and terminal half-life (11.7 +/- 2.7 hours) were not altered by cimetidine. However, there was a 20% increase in the area under the curve (p less than 0.05) and an 11% increase in systemic bioavailability (p less than 0.05) after oral administration. Dilevalol caused significant cardiac beta-blockade for more than 24 hours, but these effects were not altered by cimetidine. The pharmacokinetic changes are consistent with a decrease in first-pass extraction of a high clearance drug.

Vasodilation and reduction in forearm vascular resistance after acute administration of dilevalol

Dilevalol is a long-acting antihypertensive drug that has been demonstrated in animals to combine specific beta 2-agonist-mediated vasodilation with nonspecific beta blockade. To document vasodilation in humans, single oral doses of dilevalol, 200 mg, and placebo were randomly administered to 12 untreated hypertensive patients. Dilevalol produced significant reductions (p less than or equal to 0.01) in diastolic blood pressure throughout a 24-hour period relative to placebo, without changing heart rate. Forearm blood flow, measured hourly over the initial 4 hours after dosing, demonstrated a shift to a more vasodilated state after dilevalol administration, with significant increases in minimal forearm blood flow (4.0 vs 2.9 ml/dl tissue/min, dilevalol vs placebo, respectively; p = 0.05) and in mean average forearm blood flow (5.3 vs 4.0 ml/dl tissue/min, dilevalol vs placebo; p = 0.04). Similarly, dilevalol produced a decrease in mean forearm vascular resistance (26.5 vs 34.6 mm Hg/ml/dl tissue/min, dilevalol vs placebo; p = 0.02). In the absence of a change in heart rate, the acute hypotensive response to dilevalol in these patients appears to have resulted primarily from vasodilation and reduced vascular resistance.

Pharmacokinetics of dilevalol in normotensive and hypertensive volunteers

Dilevalol is a novel antihypertensive agent combining vasodilation due to selective beta 2-adrenergic receptor agonism with nonspecific antagonism of beta 1- and beta 2-adrenergic receptors. Studies of dilevalol's pharmacokinetics in normotensive and hypertensive volunteers have demonstrated that (1) it is rapidly and well absorbed; (2) because of extensive first-pass metabolism its absolute oral bioavailability is about 12%; (3) its mean elimination half-life is 8 to 12 hours after administration of single oral or intravenous doses to normal volunteers, a value consistent with once-daily dosing; and (4) food does not appear to alter its bioavailability or pharmacokinetics.

Antihypertensive effect of dilevalol is directly related to dose and plasma concentrations

Dilevalol is a novel antihypertensive agent combining vasodilation due to selective beta 2-adrenergic receptor agonism with nonspecific beta antagonism. To determine the relation of dilevalol dose and plasma concentration to antihypertensive effect, dilevalol (n = 15) or placebo (n = 3) was administered to 18 hypertensive subjects. The study was performed under blinded conditions during a 21-day hospitalization after a 3-week drug-free outpatient phase. In the 15 hypertensive patients receiving dilevalol orally in single morning doses of 200, 400 and 800 mg each for 5 days, the drug was shown to reduce blood pressure effectively for 24 hours at all doses. The antihypertensive effect was significantly related to dose administered and to the concentration of unchanged dilevalol measured in plasma. Dilevalol did not cause excessive changes in heart rate at rest and did not produce postural hypotension. The antihypertensive effectiveness of dilevalol was essentially the same after the first and fifth (steady state) doses at each dose level. Finally, no tendency toward rebound hypertension or tachycardia was observed after the abrupt discontinuation of dilevalol in these patients.

Influence of food on the absorption of albuterol Repetabs

A study was conducted in 12 healthy, nonsmoking male volunteers to examine the effect of food intake on the absorption profile of albuterol repeat-action tablets. This randomized crossover study consisted of two phases separated by a 1-week washout period. All subjects fasted 10 hours preceding drug administration. Each subject received two 4 mg albuterol repeat-action tablets with and without a high fat content breakfast. Plasma albuterol concentrations were determined by a gas chromatographic/mass spectrophotometric assay. Relative bioavailability was assessed by comparing areas under the plasma-albuterol concentration time curves as well as peak concentrations and time to peak concentration. No significant differences were noted between the two treatment phases in the area under the curve or peak plasma concentrations. The areas under the curve were 100 and 105 hr.ng/ml when the drug was administered with and without food, respectively. The corresponding peak plasma concentration values were 9.4 and 10.4 ng/ml, respectively. The only significant difference observed was in the maximum time to reach peak plasma concentrations, which was delayed by about 1 hour when the drug was administered with food. Therefore, food has minimal effect on the absorption of albuterol from repeat-action tablets.