A single-dose, open-label, two-treatment, two-period, two-sequence, two-way cross-over bioavailability & bioequivalence study to compare two formulation of Olmesartan 40 mg in healthy adults in fed state

Introduction: Olmesartan medoxomil is an ester prodrug commonly prescribed to treat high blood pressure, heart failure, and diabetic kidney disease. Aim: To study the bioequivalence of Olvas tablets (containing olmesartan medoxomil 40mg) of Cadila Pharmaceuticals Ltd., India with Benicar® tablets (containing olmesartan medoxomil 40mg) of Daiichi Sankyo, Inc., Parsippany, New Jersey. Materials and Methods: Forty healthy, adult, male subjects were studied in a single-dose, open-label, two-treatment, two-period, twosequence, two-way cross-over study. Detailed demographic data along with clinical examination, vital signs, medical history, laboratory tests including hematology, biochemistry, serology and urine analysis. ECG and chest X-ray were performed. Pharmacokinetic primary parameters like Cmax, AUC0-t, AUC0-∞ and secondary parameters like Tmax, t1/2, Kel, and AUC Extrapolation were calculated for both the drug formulations. Results: Demographic parameters were comparable for both the treatment arms. Olmesartan medoxomil 40mg of Cadila Pharmaceuticals Ltd was found to in the acceptance range for bioequivalence, 80.00-125.00% for the 90% confidence intervals for the difference of means of Ln-transformed parameters Cmax, AUC0-t and AUC0-∞. Conclusion: Both Olmesartan Medoxomil tablets 40mg (containing olmesartan medoxomil 40mg) of Cadila Pharmaceuticals Ltd., India with Benicar® tablets 40mg (containing olmesartan medoxomil 40mg) of Daiichi Sankyo, Inc., Parsippany, New Jersey were found to be bioequivalent.


Introduction
There is an increasing burden of chronic diseases in India and hypertension is one of the most important risk factor for global morbidity and mortality. According to World Health Organization (WHO), prevalence of hypertension is increasing globally. Approximately 1 billion people currently have hypertension (systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg). 1 Adults with uncontrolled blood pressure are at increased risk of all cause and cardiovascular mortality as compared to normotensive individuals. 2 Various class of drugs are available for the treatment of hypertension like Angiotensin converting enzyme inhibitors (ACEIs), angiotensin II receptor antagonists (ARBs), dihydropyridine calcium channel blockers, thiazide diuretics, loop diuretics, β-adrenergic blocking agents, mineralocorticoid receptor blockers, director vasodilators and centrally acting alfa-agonists. 3 Olmesartan is a drug of ARBs group. It acts by blocking the angiotensin II type 1 receptors present in the smooth muscles of vessels. 4 Olmesartan medoxomil is a prodrug which is hydrolyzed by ester hydrolysis to olmesartan during absorption from the gastrointestinal tract. The absolute bioavailability of olmesaratan is approximately 26%. It's bioavailability is independent of the food intake. The maximum plasma concentration (Cmax) of olmesartan is achieved after 1 to 2 hours of oral administration of the drug. Olmesartan is highly plasma protein bound molecule (99%). Elimination of olmesartan follows a biphasic pattern with the terminal elimination half-life of 13 hours approximately. Following a single dose up to 320 mg and multiple doses up to 80 mg, it follows linear pharmacokinetics. 5 In present study we tried to establish the bioequivalence of Olmesartan Medoxomil tablets 40mg (containing olmesartan medoxomil 40mg) of Cadila Pharmaceuticals Ltd., India with Benicar® tablets 40mg (containing olmesartan medoxomil 40mg) of Daiichi Sankyo, Inc., Parsippany, New Jersey, in healthy, adult, human subjects under fed condition. The secondary objective of the study was to evaluate safety parameters, including adverse events and clinical laboratory tests.

Study population
Forty healthy, adult, male human subjects were included in the study. Written informed consent was obtained from each subject before screening. Study specific informed consent was obtained from each participating subject before enrolling into the study. Out of 40, 38 subjects completed both the periods of the study.
Subjects were screened through demographic data evaluation, clinical examination along with vital signs measurements, medical history, laboratory tests (hematology, biochemistry, serology and urine analysis), ECG and chest X-ray (taken within 6 months prior to 1st dosing) within 21 days of 1st dosing. 2D-Echo was performed for volunteers/ subjects age 40 or above (only) as per Ethical Committee recommendations. Alcohol breath test and urine screen for abuse drugs were performed for all subjects on the day of check-in of each period. Subjects recruited to the study were confirmed for following inclusion and exclusion criteria. In each period of the study, enrolled subjects fasted (overnight) for at least 10 hours prior to schedule start-time of breakfast. Each subject received high-fat, high-calorie breakfast exactly 30 minutes prior to the schedule start-time of dosing and completed the same within 30 minutes or less of the schedule start-time of breakfast. Each subject then received a single oral-dose of either Test (T) or Reference (R) product in sitting posture along with 240 mL of drinking water at ambient room temperature as per the randomization schedule. Subjects were instructed not to chew or crush the drug but to consume it as a whole. All the in-house subjects received a standard meal at about 04.00, 08.00 and 12.00 hours after dosing in each period. During housing, all meal plans were identical for the both periods of the study. For monitoring the safety of subjects, clinical examination and vital signs measurements were performed at regular interval as mentioned in the protocol.

Blood sampling
In the present study, blood samples were collected up to 72.00 hrs post-dose, because the elimination half-life of the Olmesartan Medoxomil is approximately 13 hours. Blood samples were withdrawn by placing an indwelling cannula placed in a forearm vein or fresh clean vein puncture using a disposable sterilized syringe or a needle in case of clotting of cannula.
For this a total of 23 blood samples (5.0 ml each) were collected. The pre-dose blood sample was collected within a period of 01.00 hour and within ±02 minutes of the scheduled-time till 24.00 hours. Ambulatory blood sample at 36. 00  The blood samples were collected in pre-labelled vacutainer containing K2EDTA as an anticoagulant. After collection of blood samples, study-personnel centrifuged the samples at 3000 rpm for 10 minutes at 4 o C as soon as possible but not more than 60 minutes of the actual-time of sample collection. After centrifugation the obtained plasma samples were divided into two aliquots and stored in two different pre-labeled RIA vials. The labelled RIA vials were than stored at -20±5°C or colder till withdrawn for analysis.

Statistical and analytical methods
Pharmacokinetic primary parameters like Cmax, AUC0-t and AUC0-∞ and secondary parameters like Tmax, t1/2, Kel, and AUCExtrapolation were calculated using plasma concentration Statistical analysis was performed on pharmacokinetic parameters using SAS, Statistical Software, Version 9.4, SAS Institute Inc., CARY, USA. The Tmax from Tests (T) and Reference products (R) was compared using a nonparametric method (90% confidence interval of the difference of median Tmax of tests and reference formulation by Wilcoxon signed rank test and was accepted within a clinically determined limits).
ANOVA was performed for both un-transformed and in-transformed pharmacokinetic parameters of Cmax, AUC0-t and AUC0-∞ as well as un-transformed pharmacokinetic parameters of Tmax were calculated for Olmesartan Medoxomil using PROC GLM procedure of SAS® Version 9.4 or higher. The confidence intervals expressed as a percentage relative to the LSM of the reference treatments. The difference between Tmax was analyzed nonparametrically using Wilcoxon sign rank test.
Based on the statistical results of the 90% confidence intervals for the difference of least square means of Lntransformed Cmax, AUC0-t and AUC0-∞ of Olmesartan, conclusions were drawn whether the test formulation was bioequivalent to the reference formulation under fed condition. The acceptance range for bioequivalence was 80.00-125.00% for the 90% confidence intervals for the difference of means of Ln-transformed parameters Cmax, AUC0-t and AUC0-∞.

Results
Forty healthy, adult, male, human subjects were enrolled in the study and out of which 38 subjects completed both the periods of the study. The plasma samples from 38 subjects were assayed and analyzed for Olmesartan. Demographic variables included age, age groups, height, weight and BMI. All the included subjects were Indian and male. The demographic details are provided below in table-1. Various pharmacokinetic parameters like least squares means, ratio of means, and their associated 90% confidence intervals based on ANOVA (untransformed); geometric means, ratio of means, and their associated 90% confidence intervals based on ANOVA (Ln-transformed); and statistical comparisons are summarized in tables 2 -4.

Safety
A total of two adverse events were reported in the present study, namely cough and itching. Both the adverse events were resolved and had an unlikely relationship with the study medication. No vital sign abnormalities occurred during the study. No clinically significant adverse events were observed during the clinical examination of the subjects in both the periods of the study.

Discussion & Conclusion
This study was conducted to establish the bioequivalence of Olvas tablets 40mg (containing olmesartan medoxomil 40mg) of Cadila Pharmaceuticals Ltd., India with Benicar® tablets 40mg (containing olmesartan medoxomil 40mg) of Daiichi Sankyo, Inc., Parsippany, New Jersey 07054 in healthy, adult, human subjects under fed condition. Olmesartan is ACE inhibitor, used for the treatment of hypertension. After oral administration, the absolute bioavailability of the drug is approximately 26% with the peak plasma concentration Cmax is reached after 1 to 2 hours. The bioavailability of Olmesartan is not affected by the food.
Hypertension is one of the leading cause affecting the functioning of kidney. Pharmacokinetic profiles of olmesartan is said to be affected by both age as well as altered kindly functions. 6,7 In comparison with healthy subjects, the AUC of olmesartan is reported to be altered in patients of mild and moderate renal insufficiency. In these patients, AUC is increased by 39% and 82% respectively. 8 Based on the statistical analysis of Olmesartan under fed conditions, Olvas tablets (containing 40mg Olmesartan Medoxomil) of Cadila Pharmaceuticals Limited, India meet the 90% CI criteria for log transformed Cmax, AUC0-t & AUC0-∞, therefore have been shown bioequivalent to an equal dosage of the reference formulation, Benicar® tablets 40mg (containing olmesartan medoxomil 40mg) of Daiichi Sankyo, Inc., Parsippany, New Jersey 07054. In terms of safety, both the formulation of the drug is well tolerated during both the period of the study with no outstanding safety issues.

Source of funding
None.
Source of funding None.