A randomized, single-dose, two-sequence, two-period, crossover study to assess the bioequivalence between two formulations of clonazepam tablet in healthy subjects

Bioequivalence Study of Two Tablet Formulations of Clonazepam 2 mg: A Randomized, Open-Label, Crossover Study in Healthy Mexican Volunteers Under Fasting Conditions

INTRODUCTION

The prevalence of neurological disorders is high among the Mexican population. Clonazepam is primarily indicated to treat panic disorders, certain kinds of epilepsy such as status epilepticus, childhood motor seizures (petit mal absence, Lennox-Gastaut syndrome, and infantile spasms), anxiety, and muscle spasm. This study was performed to compare bioequivalence between two oral tablet formulations of clonazepam 2 mg in healthy Mexican volunteers under fasting conditions.

METHODS

This phase I, randomized, open-label, two-treatment, crossover study included 30 healthy volunteers. Subjects were randomly assigned to either test or reference formulation of clonazepam 2 mg. Each study period was separated by 21-day washout period. Blood samples were collected at pre-dose and up to 72 h after drug administration. Clonazepam concentrations were determined using a validated ultra-flow liquid chromatography-tandem mass spectrometric method. Pharmacokinetic parameters were determined using a non-compartmental method. Two formulations were considered bioequivalent if geometric mean ratios (test/reference) were between 80% and 125%. Safety was evaluated by recording adverse events.

RESULTS

Pharmacokinetic parameters were comparable between test and reference formulations. The mean maximum plasma concentration (Cmax) was ≈ 13 ng/mL, area under the plasma concentration-time curve from time 0 to last measurable concentration (AUC0-t) was ≈ 360 ng h/mL, time to reach maximum plasma concentration (Tmax) was ≈ 3 h, and elimination half-life (t1/2) was ≈ 43 h. Geometric mean ratios (90% confidence interval) of Cmax (99.2-115.3%), AUC0-t (100.6-110.6%), and AUC0-∞ (98.5-111.6%) were within the bioequivalence range. Seven non-serious adverse events (mostly asymptomatic hypotension) were recorded.

CONCLUSION

The test and reference formulations of clonazepam 2 mg were bioequivalent and well tolerated in healthy Mexican volunteers under fasting conditions.

PROTOCOL AUTHORIZATION NUMBER

213301410B0051 (Approved on April 13, 2021).

The Bioequivalence of Emulsified Isoflurane With a New Formulation of Emulsion: A Single-Center, Single-Dose, Double-Blinded, Randomized, Two-Period Crossover Study

Background: Emulsified isoflurane is a novel intravenous general anesthetic obtained by encapsulating isoflurane molecules into emulsion. The formulation of emulsion has been improved according to the latest regulations of the China Food and Drug Administration. This study was designed to compare the bioequivalence of the new and previous formulation emulsion of isoflurane.

Methods: In a single-center, single-dose, double-blinded, randomized, two-period crossover study, healthy volunteers received intravenous injection of 30 mg/kg of isoflurane with either previous formulation of emulsion isoflurane (PFEI) or new formulation of emulsion isoflurane (NFEI). Arterial and venous blood samples were obtained for geometric mean test/reference ratios of C_max, AUC_0-t, and AUC_0-∞, as well as their 90% confidence interval (CI90) as the primary outcome. The secondary outcomes were safety measurements such as vital signs, 12-lead electrocardiography, adverse effects, and laboratory tests; and anesthesia efficacy was assessed by Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) score, bispectral index (BIS), and loss/recovery of eyelash reflex.

Results: 24 subjects were eligible, of which 21 completed the whole experiment (NFEI n = 21, PFEI n = 23). Arterial geometric mean test/reference ratios of C_max, AUC_0-t, and AUC_0-∞ were 104.50% (CI90 92.81%–117.65%), 108.23% (94.51%–123.96%), and 106.53% (93.94%∼120.80%), respectively. The most commonly seen adverse effects for NFEI and PFEI were injection pain (38.1% vs. 34.8%), hypotension (19.0% vs. 13.0%), apnea (14.3% vs. 17.4%), and upper airway obstruction (14.3% vs. 13.0%). No severe adverse effect was observed. The effectiveness of general anesthesia was similar between the two formulations.

Conclusion: The CI90 of C_max, AUC_0-t, AUC_0-∞, NFEI, and PFEI were within the range of 80%–125%, suggesting bioequivalence between NFEI and PFEI. The safety and anesthesia effectiveness were also similar.