Randomized, open-label, two-period crossover comparison of the pharmacokinetic and pharmacodynamic properties of two amlodipine formulations in healthy adult male Korean subjects

Evaluation for Potential Drug-Drug Interaction of MT921 Using In Vitro Studies and Physiologically-Based Pharmacokinetic Models

MT921 is a new injectable drug developed by Medytox Inc. to reduce submental fat. Cholic acid is the active pharmaceutical ingredient, a primary bile acid biosynthesized from cholesterol, endogenously produced by liver in humans and other mammals. Although individuals treated with MT921 could be administered with multiple medications, such as those for hypertension, diabetes, and hyperlipidemia, the pharmacokinetic drug–drug interaction (DDI) has not been investigated yet. Therefore, we studied in vitro against drug-metabolizing enzymes and transporters. Moreover, we predicted the potential DDI between MT921 and drugs for chronic diseases using physiologically-based pharmacokinetic (PBPK) modeling and simulation. The magnitude of DDI was found to be negligible in in vitro inhibition and induction of cytochrome P450s and UDP-glucuronosyltransferases. Organic anion transporting polypeptide (OATP)1B3, organic anion transporter (OAT)3, Na⁺-taurocholate cotransporting polypeptide (NTCP), and apical sodium-dependent bile acid transporter (ASBT) are mainly involved in MT921 transport. Based on the result of in vitro experiments, the PBPK model of MT921 was developed and evaluated by clinical data. Furthermore, the PBPK model of amlodipine was developed and evaluated. PBPK DDI simulation results indicated that the pharmacokinetics of MT921 was not affected by the perpetrator drugs. In conclusion, MT921 could be administered without a DDI risk based on in vitro study and related in silico simulation. Further clinical studies are needed to validate this finding.

Glutathione S-transferase M1 and T1 genes deletion polymorphisms and blood pressure control among treated essential hypertensive patients in Burkina Faso

OBJECTIVE

Glutathione S-transferases have been associated with experimental resistance to some drugs. The present study investigated the factors associated with blood pressure control in patients with essential hypertension, especially the role of GSTT1 and GSTM1 genes polymorphisms. This cross-sectional study in Burkina Faso consisted of 200 patients with essential hypertension and under treatment.

RESULTS

In the present study, 57.5% (115/200) of patients had their hypertension under control. No statistically significant difference was found between controlled and uncontrolled groups for anthropometric and biochemical parameters as well as for GSTT1 or GSTM1 gene polymorphisms (all p > 0.05). Current alcohol consumption (OR = 3.04; CI 1.88-6.13; p < 0.001), Physical inactivity (OR = 3.07; CI 1.71-5.49; p < 0.001), severe hypertension before any treatment (Grade III [OR = 3.79; CI 2.00-7.17; p < 0.001]) and heart damage (OR = 3, 14; CI 1.59-6.02; p < 0.001) were statistically more frequent in uncontrolled essential hypertensive patients than controlled hypertensive patients.

Pharmacokinetics and bioequivalence of fixed-dose combination of candesartan cilexetil/amlodipine besylate (16/10 mg) versus coadministration of individual formulations in healthy subjects

This study compared the pharmacokinetics of a fixed-dose combination (FDC) of candesartan (16 mg) and amlodipine (10 mg) versus coadministration of individual formulations to clarify the bioequivalence of the FDC. In this randomized, open-label, single-dose, 2-treatment, 2-way crossover study, healthy Korean volunteers received a single dose of candesartan (16 mg) with amlodipine (10 mg) as either an FDC or single agents concomitantly administered, with a 2-week washout period. Serial blood samples were collected up to 72 hours after dosing for each treatment period, and plasma concentrations of candesartan and amlodipine were measured using a validated liquid chromatography-tandem mass spectrometry method. A total of 39 subjects completed the study. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for the area under the plasma concentration-time curve from time 0 to the last measurement (AUC_0-t) and the peak plasma concentration (C_max) for candesartan were 1.0182 (0.9562–1.0841) and 0.9492 (0.8726–1.0324), respectively. The GMR and 90% CI for the AUC_0-t and C_max for amlodipine were 1.0552 (1.0255–1.0857) and 1.0668 (1.0259–1.1094), respectively. In conclusion, the new FDC formulation of candesartan (16 mg) and amlodipine (10 mg) was bioequivalent to the concomitant administration of single agents. A single dose of candesartan/amlodipine as the FDC or as single agents was well tolerated.

Pharmacokinetic comparison of a fixed-dose combination versus concomitant administration of amlodipine, olmesartan, and rosuvastatin in healthy adult subjects

Objective: The aim of this study was to compare the pharmacokinetic (PK) and safety profiles of a fixed dose combination (FDC) formulation and co-administration of amlodipine, olmesartan, and rosuvastatin. Materials and methods: This study was an open-label, randomized, cross-over design conducted in healthy male volunteers. All subjects received either a single FDC tablet containing amlodipine 10 mg/olmesartan 40 mg/rosuvastatin 20 mg, or were co-administered an FDC tablet containing amlodipine 10 mg/olmesartan 40 mg and a tablet containing rosuvastatin 20 mg, for each period, with 14-day washout periods. Plasma concentrations of amlodipine, olmesartan, and rosuvastatin were measured by liquid chromatography tandem mass spectrometry. Safety was evaluated by measuring vital signs, clinical laboratory parameters, physical examinations, and medical interviews. Results: Sixty-four subjects were enrolled, and 54 completed the study. The geometric mean ratios and 90% CI for the maximum plasma concentration (C_max) and area under the curve from time zero to the last sampling time (AUC_t) were 1.0716 (1.0369,1.1074) and 1.0497 (1.0243,1.0757) for amlodipine, 1.0396 (0.9818,1.1009) and 1.0138 (0.9716,1.0578) for olmesartan, and 1.0257 (0.9433,1.1152) and 1.0043 (0.9453,1.0669) for rosuvastatin. Fourteen cases of adverse events occurred in 12 subjects. There was no statistically significant clinical difference between the formulation groups. Conclusion: The 90% CI of the primary PK parameters were within the acceptance bioequivalence criteria, which is ln (0.8) and ln (1.25). These results indicate that the FDC formulation and co-administration of amlodipine, olmesartan and rosuvastatin are pharmacokinetically bioequivalent and have similar safety profiles.

Effects of CYP2D6 and CYP3A5 genetic polymorphisms on steady-state pharmacokinetics and hemodynamic effects of tamsulosin in humans

PURPOSE

Tamsulosin is one of the most potent drugs currently available to treat benign prostatic hyperplasia. Cytochrome P450 (CYP) 2D6 and CYP3A are the two major enzymes responsible for tamsulosin metabolism. The purpose of this study was to evaluate the effects of CYP2D6 and CYP3A5 genetic polymorphisms on the pharmacokinetics and hemodynamic effects of tamsulosin in humans.

METHODS

Twenty-nine male subjects were enrolled and their CYP2D6 (*2,*4,*5,*10,*14,*21,*41, and *xN) and CYP3A5 (*5) genotypes were screened. Tamsulosin was administered daily for 6 days to assess its steady-state pharmacokinetics and hemodynamic effects according to CYP2D6 and CYP3A5 genotypes.

RESULTS

CYP2D6 group 3 (with genotype *10/*10 or *5/*10) exhibited higher plasma levels than CYP2D6 group 1 (with genotype *1/*1,*1/*2,*1/*2xN, or *2/*10xN) or CYP2D6 group 2 (with genotype *1/*10,*1/*41, or *2/*5) (trough concentrations for groups 1, 2, and 3: 1.3, 1.8, and 3.8 ng/mL, respectively [P < 0.001]; peak concentrations for groups 1, 2, 3: 8.3, 10.0, and 13.8 ng/mL, respectively [P < 0.005]). Similarly, CYP2D6 genotypes influenced the hemodynamic effects of tamsulosin based on systolic and diastolic blood pressures. However, the CYP3A5*3 polymorphism did not affect tamsulosin plasma levels and its hemodynamic effects.

CONCLUSION

The CYP2D6 but not the CYP3A5 genetic polymorphisms affected the pharmacokinetics and the hemodynamic effects of tamsulosin.

Clinical effectiveness and safety of low cost versus innovator brand amlodipine in hypertension: A single-blinded, randomized, crossover, noninferiority trial

Objectives:

A single-blinded, randomized, crossover, noninferiority trial was conducted to evaluate clinical effectiveness and safety of low-cost brand (LCB) versus innovator brand (IB) amlodipine in essential hypertension.

Materials and Methods:

The primary end-point was change of systolic blood pressure (BP) from baseline to study end. Adult patients with Stage 1 hypertension or isolated systolic hypertension were randomized to receive 5 mg amlodipine LCB or IB once daily for 6 weeks in each period in a 2 × 2 crossover manner with three follow-up visits in each sequence. In 28 evaluable patients, the reduction of systolic BP (SBP), diastolic BP, and safety profile between two brands was comparable.

Results:

The lower bound of the 95% confidence interval of the difference in reduction of SBP (−5.04 mmHg) was within the noninferiority margin of 10 mmHg.

Conclusion:

LCB amlodipine is noninferior to IB in terms of BP reduction and is a cost-effective alternative as it is less expensive than IB.

Formulations of Amlodipine: A Review

Amlodipine (AD) is a calcium channel blocker that is mainly used in the treatment of hypertension and angina. However, latest findings have revealed that its efficacy is not only limited to the treatment of cardiovascular diseases as it has shown to possess antioxidant activity and plays an important role in apoptosis. Therefore, it is also employed in the treatment of cerebrovascular stroke, neurodegenerative diseases, leukemia, breast cancer, and so forth either alone or in combination with other drugs. AD is a photosensitive drug and requires protection from light. A number of workers have tried to formulate various conventional and nonconventional dosage forms of AD. This review highlights all the formulations that have been developed to achieve maximum stability with the desired therapeutic action for the delivery of AD such as fast dissolving tablets, floating tablets, layered tablets, single-pill combinations, capsules, oral and transdermal films, suspensions, emulsions, mucoadhesive microspheres, gels, transdermal patches, and liposomal formulations.

Quantitative model for the blood pressure-lowering interaction of valsartan and amlodipine

AIMS

The objective of this study was to develop a population pharmacokinetic (PK) and pharmacodynamic (PD) model to quantitatively describe the antihypertensive effect of combined therapy with amlodipine and valsartan.

METHODS

PK modelling was used with data collected from 48 healthy volunteers receiving a single dose of combined formulation of 10 mg amlodipine and 160 mg valsartan. Systolic (SBP) and diastolic blood pressure (DBP) were recorded during combined administration. SBP and DBP data for each drug alone were gathered from the literature. PKPD models of each drug and for combined administration were built with NONMEM 7.3.

RESULTS

A two-compartment model with zero order absorption best described the PK data of both drugs. Amlodipine and valsartan monotherapy effects on SBP and DBP were best described by an I_max model with an effect compartment delay. Combined therapy was described using a proportional interaction term as follows: (D₁  + D₂ ) +ALPHA×(D₁ × D₂ ). D₁ and D₂ are the predicted drug effects of amlodipine and valsartan monotherapy respectively. ALPHA is the interaction term for combined therapy. Quantitative estimates of ALPHA were -0.171 (95% CI: -0.218, -0.143) for SBP and -0.0312 (95% CI: -0.07739, -0.00283) for DBP. These infra-additive interaction terms for both SBP and DBP were consistent with literature results for combined administration of drugs in these classes.

CONCLUSION

PKPD models for SBP and DBP successfully described the time course of the antihypertensive effects of amlodipine and valsartan. An infra-additive interaction between amlodipine and valsartan when used in combined administration was confirmed and quantified.

Generic versus brand-name drugs used in cardiovascular diseases

This meta-analysis aimed to compare the efficacy and adverse events, either serious or mild/moderate, of all generic versus brand-name cardiovascular medicines. We searched randomized trials in MEDLINE, Scopus, EMBASE, Cochrane Controlled Clinical Trial Register, and ClinicalTrials.gov (last update December 1, 2014). Attempts were made to contact the investigators of all potentially eligible trials. Two investigators independently extracted and analyzed soft (including systolic blood pressure, LDL cholesterol, and others) and hard efficacy outcomes (including major cardiovascular adverse events and death), minor/moderate and serious adverse events. We included 74 randomized trials; 53 reported ≥1 efficacy outcome (overall sample 3051), 32 measured mild/moderate adverse events (n = 2407), and 51 evaluated serious adverse events (n = 2892). We included trials assessing ACE inhibitors (n = 12), anticoagulants (n = 5), antiplatelet agents (n = 17), beta-blockers (n = 11), calcium channel blockers (n = 7); diuretics (n = 13); statins (n = 6); and others (n = 3). For both soft and hard efficacy outcomes, 100 % of the trials showed non-significant differences between generic and brand-name drugs. The aggregate effect size was 0.01 (95 % CI -0.05; 0.08) for soft outcomes; -0.06 (-0.71; 0.59) for hard outcomes. All but two trials showed non-significant differences in mild/moderate adverse events, and aggregate effect size was 0.07 (-0.06; 0.20). Comparable results were observed for each drug class and in each stratified meta-analysis. Overall, 8 serious possibly drug-related adverse events were reported: 5/2074 subjects on generics; 3/2076 subjects on brand-name drugs (OR 1.69; 95 % CI 0.40-7.20). This meta-analysis strengthens the evidence for clinical equivalence between brand-name and generic cardiovascular drugs. Physicians could be reassured about prescribing generic cardiovascular drugs, and health care organization about endorsing their wider use.

Bioequivalence evaluation of two amlodipine salts, besylate and orotate, each in a fixed-dose combination with olmesartan in healthy subjects

A fixed-dose combination of amlodipine and olmesartan is used to treat high blood pressure in patients whose hypertension is not sufficiently controlled with either drug alone. The objective of this study was to evaluate the bioequivalence of two fixed-dose combinations, ie, amlodipine orotate/olmesartan medoxomil 10/40 mg and amlodipine besylate/olmesartan medoxomil 10/40 mg, in healthy subjects. A randomized, open-label, single-dose, two-sequence, two-period, crossover study was conducted in 30 healthy adult volunteers. Blood samples were collected for up to 72 hours post-dose in each period. Safety data included the results of physical examinations, clinical laboratory tests, vital signs, an electrocardiogram, and adverse events. For both amlodipine and olmesartan, the 90% confidence intervals for the geometric mean ratios of AUC_last and time to peak plasma concentration fell within the bioequivalence acceptance criteria. The two fixed-dose combinations showed similar safety profiles. Amlodipine orotate/olmesartan medoxomil 10/40 mg was bioequivalent to amlodipine besylate/olmesartan medoxomil 10/40 mg.

Effects of genetic factors on the pharmacokinetics and pharmacodynamics of amlodipine in primary hypertensive patients

The aim of the present study was to explore the effects of common genetic polymorphisms of cytochrome P450 (CYP)3A4, CYP3A5, cytochrome P450 oxidoreductase (POR) and multidrug resistance protein 1 (MDR1) on the pharmacokinetics and pharmacodynamics of amlodipine in primary hypertensive patients. The mild-to-moderate essential hypertension patients were recruited to complete the genotyping of CYP3A4, CYP3A5, POR and MDR1 by sequencing. After a 1-week placebo washout period, the subjects received 5 mg oral amlodipine daily for 4 weeks. Serial blood samples were collected prior to the last dosing, and 2, 6 and 24 h post-dosing. Blood pressures were measured prior and subsequent to dosing, and the demographical data were also collected. The blood samples were collected for laboratory testing. The plasma concentrations of amlodipine were determined by high-performance liquid chromatography/tandem mass spectrometry. A total of 60 patients, including 31 males and 29 females, completed the 4-week treatment. The plasma concentration of amlodipine in females at each time point was significantly higher compared to males (P<0.05). However, no significant gender differences existed in antihypertensive efficacy. The genetic polymorphisms of MDR1 C3435T had a certain impact on the plasma concentration of amlodipine, but did not affect its antihypertensive efficacy (P>0.05). The genetic polymorphisms of CYP3A4*1G, CYP3A5*3 and POR A503V showed no impact on plasma concentration and efficacy of amlodipine (P>0.05). Gender and MDR1 gene polymorphism may affect the plasma concentration of amlodipine in hypertensive patients. However, there was no impact on the efficacy of amlodipine.

Glucose-β-CD interaction assisted ACN field-amplified sample stacking in CZE for determination of trace amlodipine in beagle dog plasma

A simple, sensitive and low-cost method using CE coupled with glucose-β-CD interaction assisted ACN stacking technique has been developed for quantification of trace amlodipine in dog plasma. The plasma samples were extracted with methyl tert-butyl ether. The separation was performed at 25°C in a 31.2 cm × 75 μm fused-silica capillary with an applied voltage of 15 kV. The BGE was composed of 6.25 mM borate/25 mM phosphate (pH 2.5) and 5 mg/mL glucose-β-CD. The detection wavelength was 200 nm. Because CD could diminish the interaction between drugs and matrix, and derivation groups of CD play an important role in separation performance, the effects of β-CD, and its derivatives on the separation were studied at several concentrations (0, 2.5, 5.0, 10.0 mg/mL). In this study, organic solvent field-amplified sample stacking technique in combination with glucose-β-CD enhanced the sensitivity about 60-70 folds and glucose-β-CD could effectively improve the peak shape. All the validation data, such as accuracy, precision extraction recovery, and stability, were within the required limits. The calibration curve was linear for amlodipine from 1 to 200 ng/mL. The method developed was successfully applied to the pharmacokinetic studies of amlodipine besylate in beagle dogs.

Evaluation of the dose-response relationship of amlodipine and losartan combination in patients with essential hypertension: an 8-week, randomized, double-blind, factorial, phase II, multicenter study

BACKGROUND

Despite recommendations for more intensive treatment and the availability of several effective treatments, hypertension remains uncontrolled in many patients.

OBJECTIVE

The aim of this study was to determine the dose-response relationship and assess the efficacy and safety of amlodipine or losartan monotherapy and amlodipine camsylate/losartan combination therapy in patients with essential hypertension.

METHODS

This was an 8-week, randomized, double-blind, factorial design, phase II, multicenter study conducted in outpatient hospital clinics among adult patients aged 18-75 years with essential hypertension. At screening, patients received placebo for 2-4 weeks. Eligible patients (n=320) were randomized to one of eight treatment groups: amlodipine 5 mg or 10 mg, losartan 50 mg or 100 mg, amlodipine camsylate/losartan 5 mg/50 mg, 5 mg/100 mg, 10 mg/50 mg, or 10 mg/100 mg.

MAIN OUTCOME MEASURES

The assumption of strict superiority was estimated using the mean change in sitting diastolic blood pressure (DBP) at 8 weeks. Safety was monitored through physical examinations, vital signs, laboratory test results, ECG, and adverse events.

RESULTS

The reduction in DBP at 8 weeks was significantly greater in patients treated with the combination therapies compared with the respective monotherapies for all specified comparisons except amlodipine camsylate/losartan 10 mg/100 mg versus amlodipine 10 mg. The incidence of adverse events in the group of patients treated with the amlodipine camsylate/losartan 10 mg/50 mg combination tended to be higher than for any other group (27.9%, 12/43); however, the effect was not statistically significant.

CONCLUSION

Combination amlodipine camsylate/losartan (5 mg/50 mg, 5 mg/100 mg and 10 mg/50 mg) resulted in significantly greater BP lowering compared with amlodipine or losartan monotherapy, and was determined to be generally safe and tolerable in patients with essential hypertension.

CLINICAL TRIAL REGISTRATION

Registered at clinicaltrials.gov: NCT00942344.

Comparison of the efficacy and safety of fixed-dose amlodipine/losartan and losartan in hypertensive patients inadequately controlled with losartan: a randomized, double-blind, multicenter study

BACKGROUND

Fixed-dose combination drugs may enhance blood pressure (BP) goal attainment through complementary effects and reduced side effects, which leads to better compliance.

OBJECTIVE

This study aimed to evaluate the efficacy and safety profiles of once-daily combination amlodipine/losartan versus losartan.

METHODS

This was an 8-week, double-blind, multicenter, randomized phase III study conducted in outpatient hospital clinics. Korean patients with essential hypertension inadequately controlled on losartan 100 mg were administered amlodipine/losartan 5 mg/100 mg combination versus losartan 100 mg. The main outcome measures were changes in sitting diastolic blood pressure (DBP) and sitting systolic blood pressure (SBP) and BP response rate from baseline values, which were assessed after 4 and 8 weeks of treatment. Safety and tolerability were also assessed.

RESULTS

At week 8, both groups achieved significant reductions from baseline in DBP (11.7 ± 7.0 and 3.2 ± 7.9 mmHg), which was significantly greater in the amlodipine/losartan 5 mg/100 mg combination (n = 70) group (p < 0.0001). Additionally, the amlodipine/losartan 5 mg/100 mg combination group achieved significantly greater reductions in SBP at week 8 and in SBP and DBP at week 4 compared with the losartan 100 mg (n = 72) group (all p < 0.0001). Response rates were significantly higher in the amlodipine/losartan 5 mg/100 mg group versus the losartan 100 mg group (81.4% vs 63.9% at week 4, p < 0.0192; 90.0% vs 66.7% at week 8, p < 0.001). Both treatments were generally well tolerated.

CONCLUSION

Switching to a fixed-dose combination therapy of amlodipine/losartan 5 mg/100 mg was associated with significantly greater reductions in BP and superior achievement of BP goals compared with a maintenance dose of losartan 100 mg in Korean patients with essential hypertension inadequately controlled on losartan 100 mg.

CLINICAL TRIAL REGISTRATION

Registered at Clinicaltrials.gov as NCT00940680.

Amlodipine besylate and amlodipine camsylate prevent cortical neuronal cell death induced by oxidative stress

We examined the neuroprotective effects of the long-acting third-generation dihydropyridine Ca(2+) antagonists, amlodipine besylate (AB) and amlodipine camsylate (AC), on neuronal cell death induced by oxidative stress. Cell viability and levels of free radicals and intracellular signaling proteins were measured after treating primary cultures of cortical neurons with AB, AC, and/or hydrogen peroxide (H(2) O(2) ) under various conditions. Cell viability was not affected by concentrations of AB or AC up to 5 μM but decreased at higher concentrations. Following H(2) O(2) exposure, the viability of cortical neurons decreased in a concentration-dependent manner; however, treatment with AB or AC up to 5 μM restored the viability of H(2) O(2) -injured cortical neurons. Treatment with H(2) O(2) increased the level of free radicals in cortical neurons, and pre-treatment with AB or AC counteracted this in a dose-dependent manner. Similarly, treatment with AB or AC reduced the declines in p85aPI3K, phosphorylated Akt, phosphorylated GSK-3β, heat-shock transcription factor-1, and Bcl-2 induced by H(2) O(2) , as well as the increases in cyclooxygenase-2, cytosolic cytochrome c, cleaved caspase 9, and cleaved caspase 3. Our results indicate that AB and AC exert similar neuroprotective effects by reducing oxidative stress, enhancing survival signals, and inhibiting death signals.

Pharmacokinetic comparison of orally disintegrating and conventional donepezil formulations in healthy Korean male subjects: a single-dose, randomized, open-label, 2-sequence, 2-period crossover study

BACKGROUND

Donepezil is a potent inhibitor of acetylcholinesterase, an enzyme that is targeted in the treatment of Alzheimer's disease.

OBJECTIVE

The purpose of this study was to compare the pharmacokinetic characteristics of orally disintegrating (test) and conventional (reference) donepezil formulations to satisfy the regulatory requirement for marketing.

METHODS

A single-center randomized, single-dose, open-label, 2-way crossover study with a 21-day washout period was conducted in 22 healthy volunteers. Plasma samples for the analysis of donepezil were collected up to 240 hours after drug administration. Participants received either reference or test drug formulation of 10 mg donepezil in the first period and the alternative formulation in the second period. Plasma concentrations of donepezil were determined by validated high-performance liquid chromatography coupled to tandem mass spectrometry detection. Pharmacokinetic parameters, including C(max) and AUC, were determined by noncompartmental analysis. ANOVA was carried out using log-transformed C(max) and AUC, and the mean ratios and their 90% CIs were calculated. The safety profiles and tolerabilities of the 2 formulations were also assessed based on laboratory tests, 12-lead ECGs, vital signs, and physical examinations.

RESULTS

Of the 22 participants initially enrolled, 18 healthy Korean participants completed both treatment periods. Four subjects did not complete both treatments: 3 subjects withdrew consent for personal reasons, and 1 subject experienced adverse events. No significant differences in pharmacokinetic parameters between the 2 formulations were observed. The mean (SD) age, height, and weight of the participants were 25.8 (4.1) years, 173.6 (5.7) cm, and 68.9 (7.8) kg, respectively. The mean (SD) C(max), AUC(last), and AUC(inf) for the reference formulation were 33.26 (6.58) ng/mL, 1521.69 (344.04) ng × h/mL, and 1691.46 (443.05) ng × h/mL, respectively. Corresponding values for the test formulation were 34.23 (6.79) ng/mL, 1554.33 (390.23) ng × h/mL, and 1718.27 (447.03) ng × h/mL, respectively. The median T(max) was 2 hours (range, 1-3 hours) for the reference and test formulations. The geometric mean ratios (90% CI) between the 2 formulations of donepezil were 102.9 (96.8-109.5) for C(max), 102.3 (96.1-108.9) for AUC(last), and 101.6 (95.4-108.2) for AUC(0-∞), respectively. During the study, 15 and 14 adverse events were reported for the reference and test formulations, respectively, and all were transient, mild, and resolved during the treatment period. These adverse events included 7 cases of nausea, 3 cases of headache, and 1 case each of dizziness, vomiting, chills, and sweating. All adverse events were considered related to the study drugs.

CONCLUSION

This study found that the test and reference formulations met the regulatory criteria for pharmacokinetic equivalence in these fasting healthy Korean male subjects. Both donepezil formulations appeared to be generally well tolerated.

Effect of cytochrome P450 3A5*3 genotype on the stereoselective pharmacokinetics of amlodipine in healthy subjects

Amlodipine is a racemic mixture composed of S- and R-form and metabolized stereoselectively. Cytochrome P450 3A (CYP3A) including CYP3A5 are involved in the metabolism of amlodipine and it was reported that polymorphic CYP3A5 genotype modulates the plasma levels of amlodipine and thus affect its pharmacokinetics. This study was conducted to find whether stereoselective pharmacokinetics of amlodipine was affected by the polymorphic CYP3A5 genotype. Seventeen healthy subjects were genotyped for CYP3A5*3 variant. After a single dose of 10-mg amlodipine, enantiomers of amlodipine were analyzed using HPLC-MS/MS equipped with an AGP column. Amlodipine showed stereoselective pharmacokinetics. S-amlodipine exhibited higher plasma levels than R-amlodipine in both genotype groups. S-amlodipine showed 15% higher mean peak plasma concentrations (Cmax) in CYP3A5*1/*3 carriers (3.28 ng/ml) than CYP3A5*3/*3 carriers (2.85 ng/ml) (P = 0.194) and R-amlodipine also showed 21% higher Cmax in CYP3A5*1/*3 carriers (3.33 ng/ml) than CYP3A5*3/*3 carriers (2.75 ng/ml) (P = 0.114). CYP3A5*1/*3 carriers also have 23 and 12% higher mean area under the time versus concentration curve of R-amlodipine and S-amlodipine than CYP3A5*3/*3 carriers, respectively (for R-amlodipine, 147.1 ng*h/ml for CYP3A5*1/*3 carriers versus 121.8 ng*h/ml for CYP3A5*3/*3 carriers, P = 0.234; for S-amlodipine, 161.6 ng*h/ml for CYP3A5*1/*3 carriers vs. 144.2 ng*h/ml for CYP3A5*3/*3 carriers, P = 0.353). Other pharmacokinetic parameters also showed no significant difference between them. In conclusion, the present study showed that despite the evidence that amlodipine is stereoselectively metabolized, CYP3A5*3 genotype did not affect stereoselective disposition of amlodipine. It provides the evidence that CYP3A5*3genotype plays a minor role in the interindividual variability of stereoselective disposition of amlodipine in humans.

Pharmacokinetics and bioequivalence evaluation of two formulations of 10-mg amlodipine besylate: an open-label, single-dose, randomized, two-way crossover study in healthy Chinese male volunteers

BACKGROUND

Amlodipine is a third-generation dihydropyridine calcium antagonist for the treatment of angina and hypertension. The relative bioavailability of a newly developed dispersible tablet as compared with an established branded formulation has not been reported in a Chinese population.

OBJECTIVE

The aim of this study was to assess and compare the pharmacokinetic properties, bioavailability, and bioequivalence of a newly developed dispersible tablet formulation of amlodipine besylate with those of an established branded formulation in healthy Chinese adult male volunteers.

METHODS

An open-label, single-dose, randomized, 2-way crossover study was conducted in fasted healthy Chinese male volunteers. Eligible participants were randomly assigned in a 1:1 ratio to receive 2 tablets (5 mg each) of the test or reference formulation, followed by a 2-week washout period and administration of the alternate formulation. The study drugs were administered after a 10-hour overnight fast. Serum samples were collected over 120 hours. Amlodipine concentrations in the serum were analyzed by liquid chromatography tandem mass spectrometry with positive ion electrospray ionization using the multiple reaction monitoring mode. The visible detection of the method was in the range of 0.2 to 32.0 ng/mL, and the lower limit of quantification for amlodipine was 0.2 ng/mL. The amlodipine serum concentration-time curves were used to obtain pharmacokinetic parameters including AUC(0-t), AUC(0-infinity)), and C(max). The criteria for bioequivalence were 90% CIs of 80% to 125% for AUC and 70% to 143% for C(max), according to guidelines of the State Food and Drug Administration of the People's Republic of China. Tolerability was based on the recording of adverse events (AEs), monitoring vital signs, electrocardiograms, and clinical laboratory tests at baseline and completion of the study.

RESULTS

A total of 20 healthy Chinese male volunteers (mean [SD] age, 21.4 [2.6] years [range, 1926 years]; weight, 61.3 [5.4] kg [range, 54.0-75.0 kg]; and height, 171.2 [3.6] cm [range, 162.0-177.0 cm) were included in the study. The mean (SD) C(max), T(max), AUC(0-t), and AUC(0-infinity)) values after administration of the test and reference formulations, respectively, were as follows: 5.46 (1.13) versus 5.88 (1.24) ng/mL, 7.70 (2.08) versus 9.20 (4.18) hours, 284.56 (77.59) versus 311.34 (75.97) ng/mL/h, and 331.37 (111.03) versus 358.74 (101.10) ng/mL/h. The mean (SD) t(1/2) was 38.52 (10.51) hours for the test formulation and 38.75 (7.07) hours for the reference formulation. On analysis of variance, no period or sequence effects were observed for any pharmacokinetic property; however, a significant formulation effect was observed for C(max), AUC(0-t), and AUC(0-infinity)). The relative bioavailability of the test formulation was 90.9% by mean AUC(0-t) and 91.2% by mean AUC(0-infinity). The 90% CIs for the ratios of C(max), AUC(0-t), and AUC(0-infinity) were 88.4% to 97.5%, 86.4% to 95.7%, and 85.8% to 97.0%, respectively, meeting the predetermined criteria for bioequivalence. One subject (5%) reported 2 AEs. The AEs were mild, possibly associated with study drug, and resolved spontaneously by the next evaluation. No serious AEs were reported.

CONCLUSIONS

In this small study in healthy Chinese adult male volunteers, a single 10-mg dose of the dispersible tablet formulation (test) of amlodipine besylate met the regulatory criteria for bioequivalence to the established tablet formulation (reference) based on the rate and extent of absorption. Both formulations were well tolerated.

Clinical equivalence of generic and brand-name drugs used in cardiovascular disease: a systematic review and meta-analysis

CONTEXT

Use of generic drugs, which are bioequivalent to brand-name drugs, can help contain prescription drug spending. However, there is concern among patients and physicians that brand-name drugs may be clinically superior to generic drugs.

OBJECTIVES

To summarize clinical evidence comparing generic and brand-name drugs used in cardiovascular disease and to assess the perspectives of editorialists on this issue.

DATA SOURCES

Systematic searches of peer-reviewed publications in MEDLINE, EMBASE, and International Pharmaceutical Abstracts from January 1984 to August 2008.

STUDY SELECTION

Studies compared generic and brand-name cardiovascular drugs using clinical efficacy and safety end points. We separately identified editorials addressing generic substitution.

DATA EXTRACTION

We extracted variables related to the study design, setting, participants, clinical end points, and funding. Methodological quality of the trials was assessed by Jadad and Newcastle-Ottawa scores, and a meta-analysis was performed to determine an aggregate effect size. For editorials, we categorized authors' positions on generic substitution as negative, positive, or neutral.

RESULTS

We identified 47 articles covering 9 subclasses of cardiovascular medications, of which 38 (81%) were randomized controlled trials (RCTs). Clinical equivalence was noted in 7 of 7 RCTs (100%) of beta-blockers, 10 of 11 RCTs (91%) of diuretics, 5 of 7 RCTs (71%) of calcium channel blockers, 3 of 3 RCTs (100%) of antiplatelet agents, 2 of 2 RCTs (100%) of statins, 1 of 1 RCT (100%) of angiotensin-converting enzyme inhibitors, and 1 of 1 RCT (100%) of alpha-blockers. Among narrow therapeutic index drugs, clinical equivalence was reported in 1 of 1 RCT (100%) of class 1 antiarrhythmic agents and 5 of 5 RCTs (100%) of warfarin. Aggregate effect size (n = 837) was -0.03 (95% confidence interval, -0.15 to 0.08), indicating no evidence of superiority of brand-name to generic drugs. Among 43 editorials, 23 (53%) expressed a negative view of generic drug substitution.

CONCLUSIONS

Whereas evidence does not support the notion that brand-name drugs used in cardiovascular disease are superior to generic drugs, a substantial number of editorials counsel against the interchangeability of generic drugs.

Single-dose, randomized, crossover bioequivalence study of amlodipine maleate versus amlodipine besylate in healthy volunteers

Amlodipine, marketed primarily as a besylate salt, is a calcium channel blocker used for treating essential hypertension. Amlodipine maleate is another salt that is considered, in terms of pharmacokinetics and pharmacodynamics, similar to amlodipine besylate. This open, randomized, two-period crossover trial has investigated in 24 healthy volunteers over a 144 h period the bioequivalence of amlodipine maleate tablets 10 mg versus amlodipine besylate tablets (Norvasc 10 mg). Plasma amlodipine concentrations were assessed by ultra performance liquid chromatography interfaced with a double quadrupole mass spectrometer. The area under the curve total (AUC(t)) and the area under the curve to infinity (AUC(inf)) values, peak plasma concentration (C(max)), and time to attain peak (t(max)) were not statistically different between the two drugs. AUC(t) and AUC(inf) values were higher (p < 0.05) in females than in males. The tolerability profile was comparable for the two salts of amlodipine. These findings indicate that amlodipine maleate and besylate are bioequivalent and were well tolerated, which suggests that the plasma kinetics of amlodipine depend on the properties of the molecule itself. Hence, the two salts investigated could be used interchangeably in clinical practice.

Pharmacokinetic and pharmacodynamic characteristics of a new S-amlodipine formulation in healthy Korean male subjects: A randomized, open-label, two-period, comparative, crossover study

BACKGROUND

Amlodipine, a dihydropyridine calcium channel antagonist, is prescribed for the management of angina and hypertension. It is used therapeutically as a racemic mixture, composed of S- and R-enantiomers, but its calcium channel-blocking effect is confined to S-amlodipine; R-amlodipine has 1000-fold less activity than its S-enantiomer.

OBJECTIVE

The objective of this study was to compare the pharmacokinetic and pharmacodynamic properties and safety profiles of a newly developed amlodipine formulation, composed wholly of S-amlodipine, with those of the conventionally prescribed racemic formulation.

METHODS

This randomized, open-label, 2-period, comparative, crossover study was conducted with healthy volunteers at the Gil Medical Center and Gachon Medical School, Incheon, Korea. Male subjects, aged 20 to 50 years, were eligible to participate if their weight was within 20% of ideal body weight and if they were judged by physicians to be healthy. All subjects were randomly assigned in a 1:1 ratio to 1 of 2 treatment sequences: (1) a single dose of the test amlodipine formulation (S-enantiomer amlodipine 5 mg p.o.) (Lodien [Hanlim Pharmaceutical Co., Seoul, Korea]) in the first study period, followed by a single dose of the reference amlodipine formulation (racemate 10 mg p.o.) (Norvasc [Pfizer Pharmaceuticals Korea Ltd., Seoul, Korea]) in the second study period, or (2) a single dose of the reference formulation in the first study period, followed by a single dose of the test formulation in the second period. A 3-week washout occurred between study periods. Blood samples for pharmacokinetic analysis of S-amlodipine were collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, 72, 96, 120, 144, and 168 hours after drug administration. Pharmacodynamic variables (ie, systolic and diastolic blood pressure and heart rate) were measured at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, and 72 hours after administration. Safety profiles were also assessed. Hematology, biochemistry, electrocardiography, and urinalysis were performed at baseline and end of study. Adverse events were monitored throughout the study period. Pharmacokinetic characteristics were compared using noncompartmental analysis. Pharmacokinetic equivalence was concluded if the geometric mean ratios of the plasma Cmax and AUC were within the predetermined range of 80% to 125%.

RESULTS

Twenty-six healthy Korean male volunteers were screened and 18 subjects (mean [SD] age, 23.4 [1.5] years [range, 21-26 years]; mean [SD] weight, 69.3 [6.8] kg [range, 60-88 kg]) were enrolled and completed the study. The plasma concentration-time profiles of S-amlodipine were comparable after administration of both formulations. The mean (SD) values for Cmax AUC from time 0 to the last available measurement (AUC(last)), and AUC from 0 to infinity (AUC(0-infinity)) for the reference formulation (3.0 [0.6] ng/mL, 151.4 [35.7] ng x h/mL, and 175.3 [45.1] ng x h/mL, respectively) did not differ significantly from those for the test formulation (3.1 [0.6] ng/mL, 139.7 [40.3] ng x h/mL, and 161.7 [43.8] ng x h/mL, respectively). The calculated 90% Cls for the corresponding ratios of log-transformed Cmax, AUCO(0-infinity), and AUC(last) were 97.56% to 112.51%, 86.31% to 98.74%, and 83.46% to 100.04%, respectively, which met the predetermined criteria for pharmacokinetic equivalence. Despite the single administration, significant changes in maximal blood pressure and heart rate were observed after drug administration for both formulations, compared with baseline values (all, P < 0.001). However, no significant differences were observed between the 2 formulations in terms of pharmacodynamic profiles, and no clinically relevant changes were observed for either formulation with respect to physical examination, hematology, biochemistry, electrocardiography, or urinalysis. Neither formulation caused any serious adverse events.

CONCLUSIONS

Two amlodipine formulations were found to be equivalent in terms of the pharmacokinetics of S-amlodipine. The newly developed formulation, comprised of only S-amlodipine, had pharmacodynamic profiles comparable to those of the conventional racemic amlodipine formulation in these healthy Korean male subjects. Both formulations were well tolerated.

Effect of ABCB1 (MDR1) haplotypes derived from G2677T/C3435T on the pharmacokinetics of amlodipine in healthy subjects

AIM

We aimed to investigate the effect of the ABCB1 gene on the pharmacokinetics of amlodipine.

METHODS

Based on polymorphisms of the ABCB1 gene at positions 2677 and 3435, 26 healthy male participants were divided into three groups: subjects with 2677GG/3435CC (n = 9), 2677GT/3435CT (n = 9) and 2677TT/3435TT (n = 8). After a single-dose administration of 5 mg amlodipine, plasma concentrations of amlodipine were measured and its pharmacokinetic characteristics were compared according to ABCB1 genotype.

RESULTS

The area under the plasma concentration-time curve was significantly lower in subjects with 2677TT/3435TT (140.8 +/- 35.6 ng h(-1) ml(-1)) and 2677GT/3435CT (149.8 +/- 40.1 ng h(-1) ml(-1)) than in those with 2677GG/3435CC (208.6 +/- 39.2 ng h(-1) ml(-1)) [95% confidence interval (CI) on the difference, 2677GG/3435CC vs. 2677GT/3435CT 12.0, 105.6, P < 0.01; 2677GG/3435CC vs. 2677TT/3435TT 19.6, 116.0, P < 0.01; 2677GT/3435CT vs. 2677TT/3435TT - 39.2, 57.2, P > 0.05]. The peak plasma concentrations were highest in subjects with 2677GG/3435CC (3.8 +/- 0.5 ng ml(-1)), lower in subjects with 2677GT/3435CT (3.2 +/- 0.5 ng ml(-1)) and 2677TT/3435TT (2.7 +/- 0.5 ng ml(-1)) in rank and showed a significant difference between those with 2677GG/3435CC and with 2677TT/3435TT (95% CI on the difference 0.4, 2.0, P < 0.01). However, the oral clearance was higher in subjects with 2677TT/3435TT (37.7 +/- 10.2 l h(-1)) than in those with 2677GT/3435CT (35.7 +/- 9.9 l h(-1)) and with 2677GG/3435CC (24.8 +/- 5.4 l h(-1)) and exhibited a significant difference between ABCB1 genotype groups (95% CI on the difference, 2677GG/3435CC vs. 2677GT/3435CT - 21.5, - 0.3, P < 0.05; 2677GG/3435CC vs. 2677TT/3435TT - 23.8, - 2.0, P < 0.05).

CONCLUSION

Amlodipine pharmacokinetics was affected by the genetic polymorphisms of the ABCB1 gene in humans. These findings may provide a plausible explanation for interindividual variation in the disposition of amlodipine, although our study could not explain the exact mechanism(s) by which the polymorphic ABCB1 gene paradoxically reduces the plasma levels of amlodipine. Further evaluation is thus warranted.

Comparison of efficacy and tolerability of amlodipine orotate versus amlodipine besylate in adult patients with mild to moderate hypertension: A multicenter, randomized, double-blind, placebo-controlled, parallel-group, 8-week follow-up, noninferiority trial

OBJECTIVE

The purpose of this study was to compare the efficacy and tolerability of amlodipine orotate with those of amlodipine besylate in Korean patients with mild to moderate hypertension.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study was designed as a noninferiority study. To be included in the study, previously untreated patients had to have a sitting diastolic blood pressure (SiDBP) of 90 to 109 mm Hg. Previously treated patients had to discontinue their current annhypertensive medications and have a baseline SiDBP between 90 and 109 mm Hg after a 2-week washout period. Patients who met the inclusion criteria were randomly assigned to receive 5 mg amlodipine orotate or 5 mg amlodipine besylate for 8 weeks. The medication dose was doubled (10 mg QD for either amlodipine orotate or amlodipine besylate) 4 weeks after enrollment if SiDBP was >or=90 mm Hg. The primary efficacy analysis was noninferiority of the difference in mean trough SiDBP changes from baseline for amlodipin eorotate as compared with amlodipine besylate after 8 weeks of treatment. For the secondary efficacy analysis, 2 other measures were analyzed after 8 weeks of treatment. The SiDBP response rate was defined as an SiDBP measurement<90 mm Hg at the last clinical follow-up visit or an absolute reduction of >or=10 mm Hg in SiDBP from baseline until the last clinical follow-up visit. In addition, noninferiority of the difference in mean trough sitting systolic blood pressure (SiSBP) changes from baseline was analyzed for amlodipine orotate as compared with amlodipine besylate. The drug compliance rate was estimated by pillcount.

RESULTS

Eligible patients (n=109; 43 women and 66 men) were randomly assigned to receive amlodipine orotate (n=53) or amlodipine besylate (n=56). No significant differences were found in sex, age, weight, or current smoking between the groups (all, P=NS). The proportion of patients with previous antihypertensive medications was not different between the groups (47.2% [25/53] in the amlodipine orotate group and 50.0% [28/56] in the amlodipine besylate group; P=NS). No significant differences were found in baseline SiDBP (mean [SD], 100 [6] mm Hg [range, 90-109 mm Hg] in the amlodipine orotate group and 100 [6] mm Hg [range, 90-108 mm Hg] in the amlodipine besylate group; P=NS) or in baseline SiSBP (mean [SD], 149 [14] mm Hg [range, 125-179 mm Hg] in the amlodipine orotate group and 146 [10] mm Hg [range, 123-167 mm Hg] in the amlodipine besylate group; p=NS). The mean (SD) changes in SiDBP were -15.6 (6.3) mm Hg for the amlodipine orotate group and -14.5 (5.5) mm Hg for the amlodipine besylate groups was 1.1 (5.9) mm Hg (95% CI, -0.87 to infinity), and because the lower boundary of the 95% CI was greater than -5 mm Hg, amlodipine orotate was considered noninferior to amlodipine besylate. The response rate was 48 of 51 (94.1%) in the amlodipine orotate group compared with 50 (92.6%) of 54 in the amlodipine besylate group after 8 weeks of treatment (P=NS). The mean (SD) compliance rates were 97.6% (3.6%) in the amlodipine orotate group and 96.5% (4.3%) in the amlodipine besylate group (P=NS). The incidence of drug-related adverse events (AEs) was similar between the groups (1/53 [1.9%]) in the amlodipine orotate group vs 4/55 [7.3%] in the amlodipine besylate group; P=NS). The most common drug-related AE overall was peripheral edema (2/55 [3.6%]), and the most common of all the AEs was upper respiratory tract infection (4/55 [7.3%]) in the amlodipine besylate group. The most common drug-related AE was headache (1/53 [1.9%]) in the amlodipine orotate group and peripheral edema (2/55 [3.6%]) in the amlodipine besylate group. No severe AEs were found in either group.

CONCLUSION

The reduction in SiDBP after 8 weeks of amlodipine orotate treatment was noninferior to that of amlodipine besylate in these Korean patients with mild to moderate hypertension. The SiDBP response rate and the reduction in SISBP after 8 weeks of amlodipine orotate treatment were not significantly different from those of amlodipine besylate treatment. Both agents were wel tolerated.

Assessment of sex differences in pharmacokinetics and pharmacodynamics of amlodipine in a bioequivalence study

AIMS

This study was conducted to assess the bioequivalence between two 10-mg amlodipine tablet formulations. As secondary objectives, sex-related differences and tolerability profile were evaluated.

METHODS

Thirty-six healthy volunteers (18 males and 18 females; age 20-32 years, weight 49.5-98.0 kg) were included in a randomised crossover study. Subjects were administered a single 10-mg oral dose of each formulation separated by a 14-day washout period. Plasma amlodipine levels were determined by a high performance liquid chromatographic method with tandem mass spectrometry detection.

RESULTS

All subjects completed the study and 90% confidence intervals for relevant pharmacokinetic parameters were within the ranges defined by European and US Regulatory Authorities: the geometric mean and the 90% confidence interval test/reference ratios calculated from log-transformed values were 104.54 (101.46-107.72%) for AUC(0-infinity) and 100.32 (97.41-103.33%) for Cmax. There were no serious or severe adverse events. The tolerability profile appeared to be comparable for the two products. On average, bioavailability of amlodipine was slightly higher in females than in males, but these differences could be explained by the lower body weight of women. There were no sex-related differences in drug clearance. Bioequivalence was also demonstrated within each gender group. Amlodipine treatment produced a slight decrease of systolic blood pressure and an increased in heart rate, which were more pronounced in women. The incidence of adverse events was similar in men and women.

CONCLUSIONS

The two formulations were considered bioequivalent. Although there were no relevant gender-related differences in the pharmacokinetics of amlodipine, women reached higher amlodipine concentrations most likely because of their lower body weight, and therefore, the reported pharmacodynamic effects were higher within this gender group.

Relative bioavailability and pharmacokinetics of a new sibutramine formulation in healthy male subjects: a randomized, open-label, two-period, comparative crossover study

BACKGROUND

Sibutramine is an orally administered, centrally acting antiobesity drug. Sibutramine hydrochloride monohydrate is the conventional formulation, whereas sibutramine mesylate hemihydrate is a newly developed formulation. Drugs formed from different salts may differ in their solubility profiles and dissolution rates, which may affect their rate of absorption and thus their onset, duration, and intensity of effect.

OBJECTIVE

This study was conducted to compare the relative bioavailability and pharmacokinetics of the new sibutramine formulation (test) with those of the conventional formulation (reference).

METHODS

: This was a single-center, randomized, open-label, 2-period, comparative crossover study in healthy male subjects. All subjects received a single 15-mg oral dose of sibutramine hydrochloride monohydrate (reference) and a single 17.3-mg oral dose of sibutramine mesylate hemihydrate (test), both containing 12.55 mg sibutramine base. The 2 doses were separated by a 2-week washout period. Blood samples for pharmacokinetic analysis were collected during a 72-hour period after treatment. Safety parameters were assessed, including adverse events, hematology and biochemistry, urinalysis, and electrocardiography. Plasma concentrations of the active metabolites of sibutramine (desmethylsibutramine [M1] and didesmethylsibutramine [M2]) were determined, and the pharmacokinetic characteristics of the 2 formulations were compared using noncompartmental analysis.

RESULTS

Sixteen subjects (mean [SD] age, 24.3 [2.3] years [range, 20-25 years]; mean [SD] body weight, 66.1 [5.1] kg [range, 57-77 kg]) were enrolled in and completed the study. The plasma concentration-time profiles of M1 and M2 were similar after administration of both formulations. The reference and test formulations showed pharmacokinetic equivalence with respect to M1 and M2. The relative bioavailability of the test drug was 117.6% for M1 and 102.4% for M2. The 90% Cls for the ratios of the log-transformed C(max) and AUC values were within the predetermined equivalence range of 80% to 125%. There were no significant changes in physical, biochemical, hematologic, or urinalysis variables during the study. Neither formulation was associated with any serious adverse events.

CONCLUSION

In this study in healthy male subjects, the 2 sibutramine formulations were pharmacokinetically equivalent, and the newly developed formulation had a safety profile comparable to that of the conventional formulation.