In vitro biopharmaceutical equivalence of 5-mg glibenclamide tablets in simulated intestinal fluid without enzymes

This research evaluated the biopharmaceutical equivalence in vitro of three brands of glibenclamide 5-mg tablets (reference, brand name, and generic drugs) from Lima, Peru following the guidelines of the Biopharmaceutical Classification System (BCS). Glibenclamide is a BCS class 2 drug. Quality control parameters were evaluated including hardness, weight, friability, and drug content (hardness: 2.6–2.8 kg-f; weight [mean ± SD]: 103.3–109.8 mg ± 0.27–0.53; friability: 0.19–0.55%; content: 100.65–103.3%). To assess dissolution, apparatus 2 was used at 75 rpm, 900 mL of dissolution medium (37 ± 0.5 °C) at pH 6.8; simulated intestinal fluid without enzymes was used as the dissolution medium. Samples (5 mL) were withdrawn at 5, 10, 15, 30, 45, 60, and 90 min and analyzed at 300 nm in a UV spectrophotometer. Dissolution percentages were 52.79–59.78% at 15 minutes, 59.78–64.54% at 30 mins, 79.64–85.13% at 60 min, and 98.33–99.92% at 90 min. Based on the similarity factor (f2), the dissolution profiles of the brand name (66.61) and generic (70.10) drugs were considered similar to the reference drug (i.e., f2 50–100). Dissolution efficiency was greater than 70% and mean dissolution time exceeded 30 min (p > 0.05). According to the similarity factor and dissolution efficiency, the brand name and generic drugs are biopharmaceutical equivalents in vitro with the reference drug at pH 6.8, with a percentage difference < 5%. However, glibenclamide tablets cannot be exempt from relative bioavailability studies because they did not release at least 85% of the drug within 30 minutes.