Quality assessment of nine paracetamol 500 mg tablet brands marketed in Saudi Arabia.

Two reference (R1 and R2) and seven generic (G1-G7) brands were commercially available. Four brands were single-drug, containing paracetamol only (R1, G1-G3) and five contained additional active ingredients (R2, G4-G7). All brands were immediate-release. Weight variation (n = 20, range as percent difference from mean), active substance content (n = 20, mean (SD) as percent difference from label), breaking force (n = 10, mean (SD)), and friability (n = 20, as percent weight loss) ranged from 97 to 102%, 96.1% (2.9%) to 99.8% (1.1%), 9.9 (0.4) to 21.0 (0.9) kg, and 0.017% to 0.809%, respectively. Disintegration (water medium) time (n = 6, minute: second) ranged from 02:35-03:09 to 12:49-13:10. Dissolution (phosphate buffer, pH 5.8) profile showed a mean release at 30 min of 87% to 97% of label content, with seven brands passing stage-1 (≥ 85% for each of 6 test units) and two passing stage-2 (mean of 12 test units ≥ 85%) criteria. Despite statistically significant differences between R1 and R2 and some of their corresponding generic brands in active substance content, breaking force, and amount dissolved at 30 min, all nine brands met the pre-specified quality standards.