Eight enteric-coated 50 mg diclofenac sodium tablet formulations marketed in Saudi Arabia: in vitro quality evaluation.

A reference and seven generic (G1-7) formulations were commercially available in December 2019/January 2020 and were assessed within 25-75% of manufacture-expiration period. Weight variation (range as% difference from mean, n = 20), active substance content (ASC, mean (SD) as% difference from label, n = 20), hardness (mean (SD), n = 10), and friability (% weight loss, n = 20) were 97-103%, 102.0% (3.4%), 15.4 (1.1) kg, and 0.24%, respectively, for the reference. For G2-7, they were ≤ ±5%, 98.6% (4.0%) to 109.9% (1.8%), 11.9 (0.9) to 18.3 (0.8) kg, and ≤ 0.00 to 0.75%, respectively. G1 ASC, hardness, and friability were 111.3% (1.7%), 20.1 (1.7) kg, and 1.10%, respectively. Disintegration time (n = 6) and dissolution profile (n = 8) were also determined. No formulation disintegrated or released ˃ 0.1% of label ASC in 0.1 N HCl for 2 h. The reference disintegrated in 15:00 min:seconds and released a mean (range) of 100% (99-103%) of label ASC by 45 min in phosphate buffer (pH = 6.8). G1-7 disintegrated in 8:53 to 20:37 min:seconds and released 81% (69-90%) (G1) to 109%. Except for borderline performance of G1, all formulations passed in vitro quality tests according to United States Pharmacopoeia.