Spectroscopic Determination and In vitro Bioequivalence Studies of Different Amoxicillin Capsule Brands

Amoxicillin is an aminopenicillin antibiotic, used in the treatment of several infections resulting from susceptible Gram-positive and Gram-negative, such as pneumonia, acute otitis media, acne vulgaris, bacterial endocarditis, streptococcal pharyngitis, urinary tract, Lyme borreliosis, Salmonella, Helicobacter pylori, chlamydia, and odontogenic infections. The study aimed to determine the in-vitro bioequivalence of amoxicillin capsules from various brands using physicochemical and spectroscopic parameters. Weight uniformity, friability, disintegration, dissolving tests, and UV spectroscopy were used to determine the in-vitro bioequivalence of different brands of amoxicillin capsules. The weight variation for all the capsules showed compliance with the USP specifications (≤10% weight deviation). All brands complied with the USP/BP specification for the disintegration test, as disintegration time ranged from 7 to 12 minutes. The dissolution profile of the innovator and the generic brands showed a percentage release from 80.81 – 89.11% within 30 minutes. The first-order kinetics, t1/2 and k of amoxicillin released ranged from 16.01 – 27.11 min and 2.56 – 4.33 x 10-2 min-1 respectively. A straight-line graph was obtained as a calibration curve of amoxicillin. UV absorption spectrum showed four distinctive peaks at 240, 275, 320, and 360 nm, with the maximum at 240 nm, while the percentage content of amoxicillin ranged from 90.58 ± 1.38 to 98.74 ± 0.97%.  This result complied with the BP and USP specifications. Hence, there was a strong correlation between the release rate constant, k, and time since values were ≥ 0.8087 compared with the innovator and other brands.