Bioequivalence Studies for 2 Different Strengths of Irbesartan/hydrochlorothiazide Combination in Healthy Volunteers: 300/25 mg and 300/12.5 mg Film-coated Tablets

Abstract

Two bioequivalence studies of irbesartan (CAS 138402-11-6) and hydrochlorothiazide (CAS 58-93-5) combination at 300/12.5 mg and 300/25 mg strengths were carried out in order to assess the bioequivalence of these film-coated tablet formulations in comparison with the marketed reference formulations.

Both studies were performed with 30 healthy volunteers according to an open label, randomized, 2-period, 2-sequence, crossover, single dose and fasting conditions design. In each study, test and reference formulations were administered in 2 treatment days, separated by a washout period of 7 days. Blood samples were drawn up to 72 h following drug administration in case of irbesartan and up to 24 h in case of hydrochlorothiazide. Plasma concentrations of both analytes were obtained by a validated HPLC method using MS/MS detection. Log-transformed AUC_0-t and C_max values were tested for bioequivalence based on the ratios of the geometric LSmeans (test/reference).

For both studies, the 90% confidence intervals of the geometric LSmean values for the test/reference ratios for AUC_0-t [(irbesartan: 300/12.5 mgstrength: 95.33–111.74%. 300/25 mg strength: 91.27–103.93%) (hydrochlorothiazide: 300/12.5 mg strength: 99.63–107.50%. 300/25 mg strength: 95.72–102.24%)] and C_max [(irbesartan: 300/12.5 mg strength: 98.73–115.03%. 300/25 mg strength: 97.27–112.12%) (hydrochlorothiazide: 300/12.5 mg strength: 97.34–112.06%. 300/25 mg strength: 93.29–106.38%)] were within the bio­equivalence acceptance range of 80–125%.

According to the European Guideline on the Investigation of Bioequivalence it may be therefore concluded that both test formulations are bioequivalent to the corresponding reference formulations. Overall, it was judged that both studies were conducted with a good tolerance of the subjects to study drugs.

Key words

antihypertensive drugs - bioequivalence - irbesartan - hydrochlorothiazide - pharmacokinetics

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