Enhanced effect of triazolam with diltiazem

AIMS

Triazolam, a triazolobenzodiazepine hypnotic agent, is metabolized by CYP3A4. Diltiazem is an inhibitor of this isozyme. The aim of this study was to determine if diltiazem affects plasma concentrations of triazolam in humans.

METHODS

We investigated the interaction between triazolam and diltiazem in a randomized, three-phase crossover study. Seven healthy male volunteers received orally either a single 0.25 mg dose of triazolam, a 0.25 mg dose of triazolam after a 3-day treatment of diltiazem (180 mg day-1), or a placebo. Plasma samples were collected to determine triazolam concentration over a 24 h period. The pharmacodynamic effects of triazolam were investigated using the peak saccadic velocity of eye movements (PSV), electroencephalogram (EEG), and visual analogue scale (VAS) through 8 h.

RESULTS

Diltiazem pretreatment significantly increased the area under the triazolam concentration-time curve (8.0 +/- 2.4 to 18.2 +/- 3.1 ng ml-1 h; P < 0.001; mean +/- s.d.). Peak triazolam concentration was increased (2.1 +/- 0.7 to 3.6 +/- 1.0 ng ml-1, P < 0.05) and the elimination half-life prolonged (4.1 +/- 2.1 to 7.6 +/- 1.9 h; P < 0.01). The PSV, EEG, and VAS of the triazolam plus diltiazem group revealed significant differences from the triazolam alone group or the control placebo group.

CONCLUSIONS

Diltiazem markedly affects the pharmacokinetics of triazolam and increases the intensity of its sedative effects. Inhibition of CYP3A isozyme by diltiazem may explain the observed pharmacokinetic interaction. Therefore, triazolam should be avoided when patients are using diltiazem.

Pharmacokinetics and pharmacodynamics of (+/-)-sotalol in healthy male volunteers

1. We investigated the pharmacokinetics and pharmacodynamics of (+/-)-sotalol administered orally to healthy male volunteers in single doses of 40, 80 and 160 mg and in multiple doses of 80 mg twice daily for 7 consecutive days. 2. In the single dose studies, the half-life of (-)-sotalol (7.2-8.5 h) was significantly (P < 0.01) shorter than that of (+)-sotalol (9.1-11.4 h) while the renal clearance of (-)-sotalol (110.6-126.4 ml min-1) was significantly (P < 0.01) faster than that of (+)-sotalol (102.2-110.1 ml min-1). In the multiple dose studies, similar differences in the pharmacokinetics of (+)- and (-)-sotalol were observed. In addition, the pharmacokinetics of both (+)- and (-)-sotalol on day 4 were shown to be essentially the same as those on day 7. 3. In pharmacodynamic examinations, (+/-)-sotalol prolonged QTc intervals on electrocardiograms dose-dependently after single doses of 80 and 160 mg (3.81 +/- 2.96%, 13.23 +/- 5.66%). The correlation between the plasma concentration of (+/-)-sotalol and prolongation of QTc intervals was nearly linear, and showed no hysteresis. 4. In conclusion, we demonstrated that QTc interval was prolonged with a linear correlation to the plasma concentration of (+/-)-sotalol. In addition, our study suggested that differences in the pharmacokinetics of (+)- and (-)-sotalol may be attributable to faster urinary excretion of (-)-sotalol.

[Influence of multiple-dose administration of cefetamet pivoxil on blood and urinary concentrations of carnitine and effects of simultaneous administration of carnitine with cefetamet pivoxil]

Cefetamet pivoxil (CEMT-PI), a drug of pivaloyloxymethyl group, was investigated for its impact on the carnitine blood homeostasis and renal excretion upon administering CEMT-PI alone, and CEMT-PI simultaneously with carnitine. 500 mg of CEMT-PI (group A) and 500 mg of CEMT-PI and an equimolar amount (200 mg of carnitine) of levocarnitine chloride (group B) were administered twice a day for 7 and 1/2 consecutive days to 5 healthy volunteers (group A) and 3 healthy volunteers (group B). No serious side effects nor abnormal values in physical and laboratory tests were observed throughout the study in both groups. During the treatment period, plasma total carnitine decreased slowly down to 25.5 microM (group A) and 38.8 microM (group B) and plasma free carnitine reached steady state levels at 17.7 microM (group A) and 29.2 microM (group B) on day 5. These concentrations represent 45 and 37% in group A, 66 and 58% in group B of the average pre-treatment baseline levels. Plasma pivaloylcarnitine quickly reached plateau levels of 6.12 microM (group A) and 4.05 microM (group B) on day 4. After treatment stop, plasma total and free carnitine returned to the pretreatment baseline level within 5 days (group A) and 3 days (group B), and plasma pivaloylcarnitine was detectable until day 7 of the treatment-free follow up in both groups. Although carnitine was given concurrently at a dose equimolar to the ingested amount of pivalic acid in group B, the plasma total and free carnitine exhibited a decrease. This was considered attributable to the fact that the bioavailability of carnitine is as low as 16% when administered orally, which is considerably less compared to the 55% bioavailability of cefetamet pivoxil.

Pharmacokinetics and safety of a novel, long-acting, prodrug-type potassium channel opener, Y-27152, in healthy volunteers

The pharmacokinetics and safety of a novel, long-acting, prodrug-type K(+)-channel opener, Y-27152, were investigated in healthy male volunteers. In the first phase, single oral doses of 0.1, 0.25, 0.5, 0.75, and 1.0 mg of Y-27152 (n = 3-6 per dose) were given after overnight fasts in a dose-escalating manner. The 0.75-mg dose was given both after an overnight fast or after food to examine the effects of food intake. In the second phase, multiple doses of Y-27152 were taken after meals once daily for 7 consecutive days. In part A of this phase, either placebo (n = 3) or 0.5 mg of Y-27152 (n = 6) was taken for 7 days, and in part B of this phase 0.5-, 0.75-, and 1.0-mg doses were taken in a dose-escalating manner for 1,3, and 3 days, respectively (n = 9). In the single-dose study, peak concentration (Cmax) and area under the plasma concentration-time curve (AUC) of main active metabolite (Y-26763; M1) increased in parallel with dosage. This dose-linearity was less obvious with Y-27152, which had an AUC approximately 6 to 10 times less than that of M1. Administration with food at 0.75 mg resulted in a small but significant decrease (approximately 10%) in the Cmax and AUC of M1. At doses of 0.5 mg or higher, participants experienced headaches and palpitations, which were probably due to the vasodilatory effects and did not require treatment. Mean diastolic blood pressure significantly decreased and pulse rate increased at doses of 0.5 mg or higher compared with predose values. Plasma renin activity was significantly elevated 4 hours after the administration of the 0.75- and 1.0-mg doses, but showed no significant change at 0.5 mg. In the multiple-dose study, the time profile of the plasma concentration of M1 approximately coincided with the simulation curves worked out using the pharmacokinetic parameters obtained in the singledose study. The incidence of headaches tended to increase with dose in part B, but drug administration was not discontinued in any case. Plasma renin activity again increased 4 hours after administration. In phase B of the multiple-dose study, diastolic blood pressure decreased and pulse rate increased compared with predose values. Y-27152 was metabolized to M1 and well tolerated in healthy volunteers, and its pharmacologic effects were likely caused by vasodilation, which could make it an effective antihypertensive agent.

Pharmacokinetic and pharmacodynamic properties of FK070 (KDI-792), a novel thromboxane receptor antagonist/thromboxane synthetase inhibitor, after single and multiple oral administrations to healthy volunteers

FK070, a thromboxane A2 (TXA2) receptor antagonist/TXA2 synthetase inhibitor, was given orally to healthy male volunteers in a single- and multiple-dose study. In the single-dose study (200, 300, 400 mg), the area under the plasma concentration-time curve (AUC) and the maximum plasma concentration (Cmax) increased non-linearly with dose, while the mean elimination half-life (V0) was essentially unchanged (3.9-7.3h). Recovery of the unchanged drug in the urine was 12-25%. Cmax and AUC as determined with 200 mg of drug after a meal decreased by about 60 and 30%, respectively. Ex-vivo platelet aggregation in the plasma by a TXA2 analogue, U46619, was almost completely inhibited within 1 h, after all doses of drug, with a significant dose-dependent inhibition maintained for 8 h or more, which was much longer than was expected from drug plasma concentration. The aggregation by adenosine diphosphate (ADP) was inhibited to a lesser extent. FK070 also inhibited TXA2 synthetase as evidenced by decreased production of TXB2 and reciprocally increased production of 6-keto-prostaglandin F1 alpha in the serum during ex-vivo whole blood coagulation. These effects peaked 1 h after drug and lasted until 4 h with the higher doses. In the multiple-dose study (300 mg, twice a day, after meals for 6.5 days), drug concentrations in the plasma were well fitted to a three-compartment open model with first-order absorption. FK070 afforded extensive inhibition of platelet aggregation by U46619 throughout the administration period, with a significant inhibition lasting as long as 48 h after conclusion of administration. No clearly drug-related changes were found in routine laboratory tests, subjective and objective findings, or vital signs. FK070 was concluded to be well tolerated and to provide long-lasting blockade of TXA2 receptors, and plasma concentration-dependent inhibition of TXA2 synthetase in the platelets.

Single- and multiple-dose pharmacokinetics of AM-1155, a new 6-fluoro-8-methoxy quinolone, in humans

The pharmacokinetics of AM-1155, a new 6-fluoro-8-methoxy quinolone, was examined in healthy male volunteers after the oral administration of a single dose of 100, 200, 400, or 600 mg and multiple doses of 300 mg twice daily for 6.5 days (13 total doses). Throughout the whole study period, AM-1155 was well tolerated in every subject. In the single-dose study, the concentrations in serum reached a peak between 1 and 2 h, and the peak concentrations were 0.873, 1.71, 3.35, and 5.41 micrograms/ml at the doses of 100, 200, 400, and 600 mg, respectively. The elimination half-life was 7 to 8 h, independently of the doses. The unchanged drug was excreted mainly in the urine, with 82 to 88% of the doses appearing for 72 h. The fecal recovery of the unchanged drug amounted to 5.7% for 72 h after a single oral administration of a 400-mg dose. Urinary excretion of metabolites was minimal. The serum protein binding was 20%, independently of the concentrations in serum. The concentrations in saliva were approximately 80% of those in serum. The intake of food had no effect on the pharmacokinetic parameters and urinary excretion of AM-1155 except the slight decrease in area under the concentration-time curve. The concurrent administration of probenecid prolonged the elimination half-life, increased the area under the concentration-time curve, and decreased the apparent total body clearance, renal clearance, urinary recovery of unchanged drug, and the excretion ratio (intrinsic renal clearance of AM-1155/creatinine clearance). This indicated that the tubular secretion contributed to the renal excretion of AM-1155. In the multiple-dose study, the concentrations of AM-1155 in serum and urine reached a steady state within 2 to 3 days. The measured concentrations in serum fitted well the simulation curve, which reflected the persistence of linear pharmacokinetics of AM-1155. In conclusion, AM-1155 is expected to be clinically useful because of its potent antibacterial activity and favorable pharmacokinetics.

Intron length variation of the Adh gene in Brachyscome (Asteraceae)

Eighteen polymerase chain reaction (PCR) products of the partial sequence of the Adh (alcohol dehydrogenase) gene from 10 Brachyscome species were sequenced and compared. These products contained the 5' three fourths of exon 4 and whole sequences of intron 3. They varied extensively in length due to the differences in length of intron 3. A total of 10 long insertions were flanked by direct repeats of 5 to 12 bp sequences, indicating inserted elements. These inserted elements were classified into the following five categories based on nucleotide sequence characteristics and length; (1) a region homologous to that of 5S RNA genes (5S DNA), (2) A-rich structure at the 3' end-like short interspersed elements (SINEs) in animals, (3) a sequence of 280 bp with no characteristic features, (4) a sequence of 125 bp with no characteristic features, (5) termini of 11 bp inverted repeats flanked by 5 bp sequence of direct repeats characteristics of a transposon.

Pharmacokinetic and pharmacodynamic analysis of a novel leukotriene biosynthesis inhibitor, MK-0591, in healthy volunteers

1. The pharmacokinetic and pharmacodynamic properties of a novel 2-indolealkanoic acid derivative (MK-0591), a potent inhibitor of leukotriene biosynthesis, were investigated in healthy male Japanese volunteers. Single oral doses of 50, 125, 250 and 500 mg and multiple oral doses of 125 mg twice daily for 9.5 days and 250 mg once daily for 10 days were administered. 2. After the single-dose administration following overnight fasting, Cmax and AUC of MK-0591 in plasma increased in a dose-dependent manner, while elimination half-life remained constant (11.2-13.2 h) irrespective of dose. Food intake decreased Cmax and AUC by 71% and 68%, respectively, at a dose of 250 mg. With respect to multiple-dose administration before meals, there were no significant differences in the pharmacokinetic parameters between the first and last days, indicating a lack of significant accumulation of MK-0591 in plasma. Urinary recovery as the unchanged form was negligible throughout the study. 3. Ionophore-stimulated production of leukotriene B4 (LTB4) in blood ex vivo was inhibited significantly from 1 h until 12 to 48 h after single-dose administration as compared with predose value. In parallel, the urinary excretion of endogenous leukotriene E4 (LTE4) was significantly decreased from 4 to 8 h until 48 to 72 h after drug administration. Reduction of ionophore-stimulated LTB4 biosynthesis and urinary excretion of LTE4 following single administration of MK-0591 was statistically significant as compared with placebo group, and the duration of inhibition of LTB4 biosynthesis was dose-related.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of combination of a tissue-type plasminogen activator and an endothelin receptor antagonist, FR139317, in the rat cerebral infarction model

We were interested to investigate if a combination of a modified tissue-type plasminogen activator, SUN9216, which is constructed by modifying a single amino acid (Asn117-Gln117) to yield a tissue-type plasminogen activator lacking finger and growth factor domains with a long half-life in blood, and an endothelin receptor antagonist, FR139317, (R)2-[(R)-2-[(S)-2[[1-(hexahydro-1H-azepinyl)]carbonyl]amino-4- methyl-pentanoyl]amino-3-[3-(1-methyl-1H-indolyl)]propionyl)amino-3- (2-pyridyl)propionic acid, has greater thrombolytic efficacy than a thrombolytic agent alone in reducing the size of cerebral infarction. The thrombotic occlusion of the rat middle cerebral artery was induced by a photochemical reaction between rose bengal and green light, which causes endothelial injury followed by platelet adhesion and formation of a platelet-rich thrombus. SUN9216 (1 mg/kg) was injected intravenously 30 min after the middle cerebral artery occlusion and the time for reopening of the middle cerebral artery by SUN9216 was monitored for a 60-min period under an operating microscope. In the rats in which thrombolysis was achieved with SUN9216, the size of the cerebral infarction was significantly (P < 0.05) reduced as compared with that in the rats treated with saline and was comparable to the reduction produced by the combination doses. It is concluded that, under the present experimental conditions, endothelin may not be involved in the impaired local cerebral blood flow after thrombolysis.

Time course of appearance of ofloxacin in human scalp hair after oral administration

The time course of appearance of antimicrobial ofloxacin (OFLX) in human scalp hair was monitored in three healthy male volunteers after the oral administration of 100 mg OFLX three times daily for 2 consecutive days. Hair samples were collected from each subject by plucking several strands of frontal hair every day from 1 till 16 days after administration. A single hair was dissolved in 1 M NaOH to extract OFLX by chloroform, and the drug was measured by high-performance liquid chromatography and fluorescence detection. OFLX started to appear in the hair 1 to 3 days after administration and reached the maximal level approximately 4 to 9 days, remaining at almost the same level thereafter. This finding suggests the slow transfer of OFLX from hair follicle cells to hair matrix may be due to the slow dissociation of OFLX from bound melanin.

Pharmacokinetics and tolerance of DU-6859a, a new fluoroquinolone, after single and multiple oral doses in healthy volunteers

The pharmacokinetics and tolerance of DU-6859a, 7-[(7S)-7-amino-5-azaspiro[2,4]heptan-5-yl]-8-chloro-6-fluor o-1-[(1R, 2S)-2-fluoro-1-cyclopropyl]-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid sesquihydrate, were investigated in healthy male Japanese volunteers after single (25, 50, 100, and 200 mg) and multiple (100 mg three times a day for 6 days plus once a day on the 7th day and 50 mg every 12 h for 13 doses) oral doses. DU-6859a was well tolerated at all doses, and all 36 subjects completed the study; mild transient soft stool in five volunteers and mild transient diarrhea in one volunteer on the multiple-dose (100 mg three times a day) study were the only side effects reported. No drug crystals were observed in the urine after the single 200-mg dose and the 100-mg three times a day regimen. DU-6859a was rapidly absorbed in the fasted state. The mean maximum concentration in serum (Cmax) ranged from 0.29 to 1.86 micrograms/ml for the 25- to 200-mg dose, and the mean time to reach Cmax ranged from 1.0 to 1.3 h. The terminal half-life ranged from 4.4 to 5.0 h. The area under the curve increased dose dependently. The serum protein binding of the drug was approximately 50%. The apparent volume of distribution clearly exceeded 1 liter/kg, suggesting good tissue penetration. Within 48 h, the cumulative urinary recovery of unchanged drug amounted to 69 to 74% of the dose administered, while fecal excretion up to 48 h after the 200-mg dose accounted for ca. 3% of the dose. Food intake did not affect the rate and extend of absorption of DU-6859a to a clinically significant extent. During multiple oral dosing, the accumulation of the drug in serum was close to the theoretically predicted values, which indicated that there was virtually no drug accumulation.

Pharmacokinetic properties of a novel gastric proton pump inhibitor, (+/-)-2-[(4-methoxy-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-9- yl)sulfinyl]-1H-benzimidazole sodium salt, in healthy subjects

The pharmacokinetics and safety of TY-11345 [(+/-)-2-[(4-methoxy-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridin-9- yl)sulfinyl]-1H-benzimidazole sodium salt], a novel gastric proton pump inhibitor, were studied in healthy male volunteers after single (20, 40, and 80 mg) and repeated oral doses (60 mg, once daily for 7 days) as enteric-coated tablet. At the single doses of 20 and 40 mg, intragastric pH was continuously monitored in each of two subjects. No abnormal findings definitely attributable to the test drug were observed throughout the study. In the single-dose study, the maximum plasma concentration (Cmax) and area under the plasma concentration-time curve of TY-11345 increased in a dose-proportional manner. The time to reach Cmax was about 3 h after dosing and plasma concentrations declined thereafter with a half-life of about 1 h irrespective of dose. The effect of food intake on the pharmacokinetic parameters of TY-11345, which was evaluated at the dose of 40 mg in a cross-over design, was not significant. TY-11345 was not detected in urine unchanged, while a main metabolite and its conjugate were identified in urine as 32-38% of the dose. An intragastric pH value over 4 was obtained about 3 h after the administration of 40 mg and maintained for more than 5 h, despite the fall of plasma concentration. This effect was less obvious at a dose of 20 mg. In the multiple-dose study, the pharmacokinetics exhibited no substantial difference between the first and last doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and safety of NM441, a new quinolone, in healthy male volunteers

The safety and pharmacokinetics of NM441, a prodrug of a new thiazeto-quinoline carboxylic acid derivative, NM394, were evaluated in healthy male volunteers given the drug orally in single doses of 20, 50, 100, 200, and 400 mg, and multiple doses of 300 mg twice daily for 6.5 days. No remarkable abnormalities were observed in symptoms, physical tests, laboratory tests, electrocardiogram (ECG), electroencephalogram (EEG), or equilibrium test. The mean plasma concentrations of active metabolite NM394 peaked between 0.5 and 1.0 hours, and the maximum concentrations were 0.68, 1.09, and 1.88 micrograms/mL at doses of 100, 200, and 400 mg, respectively. The mean half-lives were 7.7 to 8.9 hours and were not affected by dose. The mean urinary excretion rates of NM394 were 46.0, 38.3, and 30.6% of the doses within 48 hours, respectively, and other metabolites were excreted in urine by 7% of the doses. The mean salivary concentrations of NM394 were approximately 20% of the plasma concentrations. The mean fecal excretion rates of NM394 and NM441 were 52.9 and 4.2%, respectively within 72 hours after dosing of 400 mg. The Cmax, AUC, and urinary excretion rates were not altered by food intake, whereas the Tmax was prolonged slightly. In the multiple-dose study, the steady state of plasma concentration of NM394 was achieved on day 3 or 4, and further accumulation did not occur thereafter. The mean urinary excretion rate of NM394 was 49.0% during and 48 hours after the multiple administration. The acceptable safety and tolerance and defined pharmacokinetic characteristics of NM441 support further testing.

Using ofloxacin as a time marker in hair analysis for monitoring the dosage history of haloperidol

Hair samples were obtained 1-5 months after ingestion of the antimicrobial ofloxacin, which had been given for 1 or 3 days at the commencement of haloperidol administration, or when its dosage was reduced. The axial distribution of ofloxacin, haloperidol and its active metabolite, reduced haloperidol, was analysed in segments from single strands of hair. Ofloxacin was detected where the content of haloperidol and reduced haloperidol along the hair shaft showed a sharp change, corresponding to the change in dose. When we matched the time scale of the dosage history to the growth rate, which was estimated using ofloxacin as the time marker, the distribution of the haloperidol and reduced haloperidol precisely coincided with the rise and fall in the dose of haloperidol. These findings demonstrate that ofloxacin can serve as a time marker when drug distribution along the hair shaft is used to obtain the drug exposure history of an individual.

Studies on the constituents of Ailanthus integrifolia

A new phenolic glycoside, 3,4,5-trimethoxyphenol-1-(6-xylopyranosyl)glucopyranoside, was isolated together with twenty known compounds identified as koaburaside, 3,4,5-trimethoxyphenol, 5,7-dihydroxychromone-7-neohesperidoside, naringin, neoeriocitrin, p-coumaric acid, vanillin, vanillic acid, coniferyl aldehyde, ferulic acid, trans-triacontyl-4-hydroxy-3-methoxycinnamate, p-methoxycinnamic acid, 2,6-dimethoxybenzoquinone, 2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione, 2-acetylnaphtho[2,3-b]furan-4,9-dione, 2-(1-hydroxyethyl)-6-methoxynaphtho[2,3-b]furan-4,9-dione, 2-acetyl-6-methoxynaphtho[2,3-b]furan-4,9-dione, specioside, jioglutin C and rehmaglutin D from the bark of Ailanthus integrifolia Lamk (Simaroubaceae).

Pharmacokinetics and safety of BO-2727, a new injectable 1-beta-methyl carbapenem antibiotic, and its effect on the faecal microflora in healthy male volunteers

The safety and pharmacokinetics of BO-2727, a new injectable 1-beta-methyl carbapenem antibiotic, and its effect on the faecal microflora were evaluated in single- and multiple-dose studies involving twenty-four healthy male adult volunteers following a preliminary safety evaluation of 25, 50 and 125 mg iv doses in six volunteers. BO-2727 was administered by iv infusion over 30 min. There was a good correlation between BO-2727 concentrations assayed by HPLC and a microbiological method; the HPLC results were used in the pharmacokinetic analysis. The single-dose study indicated that plasma concentration versus time curves at doses of 250, 500 and 1000 mg were well described by a two-compartment open model. The mean (+/- S.D.) elimination half-life ranged from 1.41 +/- 0.21 h to 1.54 +/- 0.10 h, and the peak plasma concentrations (Cmax) and the area under the plasma concentration versus time curves increased linearly with the dose. The mean urinary recoveries within the first 24 h were 70.63 +/- 5.24% to 77.38 +/- 4.55% of the dose. The highest concentration of BO-2727 in saliva was 0.72 mg/L which was reached 1 h after the start of the 1000 mg infusion and accounted for approximately 1% of the Cmax. No BO-2727 was found in faecal samples collected 24 and 48 h after a single 1000 mg dose. In the multiple-dose study, BO-2727 500 mg bd was administered for 4.5 days. There were no obvious differences in plasma concentrations and urinary recoveries between the single- and multiple-dose regimens. BO-2727 did not accumulate as determined by plasma concentrations and urinary recoveries. No marked changes in the aerobic and anaerobic faecal microflora were observed during multiple-dose administration. There were no significant adverse reactions, and likewise no abnormalities in physical and laboratory examinations that were definitely related to the drug.

Pharmacokinetic and pharmacodynamic profiles of CS-518, a selective, long-lasting thromboxane synthase inhibitor, after single and multiple oral administration to healthy volunteers

A selective thromboxane (TX) synthase inhibitor, CS-518, was orally administered to healthy male Japanese volunteers and the pharmacokinetic and pharmacodynamic properties were investigated. The time profile of drug concentrations in plasma was determined, and the effects of the drug on platelet aggregation in plasma induced by arachidonic acid (AA) and adenosine diphosphate (ADP) ex vivo were examined. The production of TXB2 and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in serum during whole blood coagulation ex vivo also were examined. In the single-dose study (50, 100, and 200 mg), plasma concentrations of the drug were well fitted to a one-compartment open model with first-order absorption. The area under plasma concentration curve (AUC) and maximum plasma concentration (Cmax) showed dose-related increases, whereas the mean elimination half-lives remained rather constant (.68-.92 hour). The drug was recovered in urine by 32 to 37% and 62 to 65% as unchanged and conjugated forms (acylglucuronide), respectively, showing almost complete absorption of CS-518. The effect of food intake on the pharmacokinetics of CS-518 was determined at the dose of 100 mg. The time to reach Cmax was prolonged from .42 to 2.08 hours and the Cmax was decreased by about 66%, whereas the AUC and urinary recovery showed no significant changes. The platelet aggregation in plasma induced by AA was markedly inhibited, whereas the secondary aggregation induced by ADP was inhibited to a much less degree. Platelet aggregation by AA was almost completely inhibited 2 hours after administration of any dose and the duration for maintaining the significant inhibition tended to depend on the dose ranging from 48 to 72 hours after administration, which was much longer than expected from the plasma concentration of drug.(ABSTRACT TRUNCATED AT 250 WORDS)

A prospective study for validation of Bayesian prediction approach to adjust individual lidocaine dosage

A Bayesian approach, in which the estimates of the population pharmacokinetic parameters of lidocaine reported by Vozeh et al. [1984 a and b] and one measurement of serum lidocaine concentration as feedback information were utilized, was prospectively evaluated in 20 Japanese patients. The concentration of lidocaine in serum sampled from each patient at 1.5 to 3 hours after the commencement of i.v. lidocaine therapy was measured and the most likely pharmacokinetic parameters of that patient were predicted by the Bayesian program for microcomputer. Having the predicted parameters, we got the concentrations of lidocaine at 12 and 24 hours (C12 and C24) after starting the therapy within the recommended therapeutic range (2-5 micrograms/ml) by adjusting the individual dosage. As a result, the values of C12 and C24 remained within the therapeutic range in all patients and in all except one, respectively. The mean % prediction error (measured minus predicted concentration standardized by measured one) and its 95% confidence interval were 1.8% and -11.4 to 14.7% for C12, and -2.3% and -11.9 to 7.4% for C24, showing that the prediction of both C12 and C24 was not biased. The correlation coefficients between the measured and predicted concentrations were 0.574 for C12 and 0.721 for C24 (p < 0.01). From these findings, the present Bayesian method implemented with the estimates of pharmacokinetic parameters in a Swiss patient population is useful for sufficiently accurate and precise assessment of individual dosage requirement within a few hours after starting lidocaine therapy.

Changes in plasma and urinary 11-dehydrothromboxane B2 in healthy subjects produced by oral CS-518, a novel thromboxane synthase inhibitor

When 50 mg CS-518, a novel thromboxane (TX) A2 synthase inhibitor, was orally administered to healthy male volunteers, the plasma concentration of CS-518 peaked after 0.5 h and then decreased with a half-life of 0.44 h. There was no significant change in the plasma concentration of circulating TXB2, whereas that of circulating 11-dehydrothromboxane B2 (11-dhTXB2), an enzymatic metabolite of TXB2, was significantly decreased from 0.5 h to 24 h after administration; the maximal decrease to about 25% of the pre-dose value was found at 6 h. After CS-518 100 mg b.d. for 4.5 days, plasma 11-dhTXB2 was suppressed to the same extent as after the single dose of 50 mg from 6 h after the initial dose throughout the administration period. The urinary excretion of 11-dhTXB2 corrected for the creatinine level was significantly decreased by 70-84% throughout the treatment. These results suggest that CS-518 causes long-lasting inhibition of TXA2 synthase despite its rapid elimination from plasma, and that circulating 11-dhTXB2 in plasma and its urinary excretion can serve as a quantitative index of TXA2 synthase inhibition in vivo by CS-518.

Pharmacokinetics of intravenous ataprost alfadex, a new prostaglandin I2 analog in healthy volunteers

Ataprost alfadex [5(E),-6,9-deoxa-6,9 alpha-methylene-15-cyclopentyl-16,17,18,19,20-pentanor- PGI2 alpha-cyclodextrin clathrate] is a novel PGI2 derivative. From animal studies, it is expected to be a more potent inhibitor of platelet aggregation and less hypotensive than PGI2. The pharmacokinetics of ataprost were studied in 9 healthy male volunteers during and after i.v. infusion for 2 hours at the rates of 2.5 (n = 5) and 10 ng/kg/min (n = 4). Both treatments were well tolerated by the subjects. At the end of the infusion, plasma levels of 191 +/- 76 (mean +/- SD) and 645 +/- 191 pg/ml were reached, declining rapidly with half-lives of 6.7 +/- 3.0 and 5.5 +/- 0.84 minutes at the lower and higher infusion rates, respectively. The area under the plasma concentration-time curve extrapolated to infinity increased with the dose as follows: 28.7 +/- 9.8 and 80.9 +/- 24.8 ng.min/ml. The unchanged drug was not detected in urine but a metabolite was recovered in it, reaching up to 6.0 +/- 0.85% of the total dose within the first 24 hours, the most part of which was recovered within the first 4 hours.

Presence in Kawasaki disease of antibodies to mycobacterial heat-shock protein HSP65 and autoantibodies to epitopes of human HSP65 cognate antigen

The central features of Kawasaki disease are immune activation and cytokine-mediated generalized vasculitis. To identify the predisposing factors, we examined the antibody response to BCG antigens, since reactivation of a previous BCG inoculation site is an early, specific manifestation of this disease. BCG antigens were separated on SDS-PAGE, transferred to membrane, and incubated with acute- and convalescent-phase sera of 21 patients with Kawasaki disease. Sera were also examined for the presence of antibodies to mycobacterial 65-kDa heat-shock protein (HSP65), and to its human homolog P1 antigen using synthetic peptides of nonhomologous region. To demonstrate the HSP65-sensitized T cells, in vitro proliferation assay was performed. All convalescent, but not acute phase, sera showed a strong antibody reactivity against 65-kDa protein. The reactivity was directed to recombinant HSP65. Non-cross-reactive sequences between rHSP65 and human HSP65 cognate were synthesized. The sera recognized these peptides of rHSP65 and autologous P1 antigen. Peripheral lymphocytes proliferated following the addition of rHSP65 (stimulation indices, 2.16-7.82; mean, 4.54). These findings suggest that HSP65 may be the most potent factor predisposing to Kawasaki disease, and that an autoreactivity to the epitope of the human HSP65 homolog may be related to the susceptibility to the disease.