In-Vitro Comparative Evaluation of Different Co-Trimoxazole Tablet Products Obtained From Drug Retail Outlets in Addis Ababa

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Addis Ababa University


Evaluation studies provide a means of identifying quality differences between same products obtained from various manufacturers and quality evaluations are crucial in the era of increasing resistance to antibacterial agents The introduction of trimethoprim in combination with sulphamethoxazole constitutes an important advance in the development of clinically effective antimicrobial agents. In much of the world the combination of sulphamethoxazole with trimethoprim in the proportion of 5 to 1 is known as Co-trimoxazole. Co-trimoxazole has been used in a diverse range of infections due to sensitive bacteria and is widely prescribed for various indications. By virtue of sequential blockade of microbial folic acid synthesis the antimicrobial combination has excellent in vitro inhibitory activity against many common respiratory and urinary tract pathogens, as well as many nosocomial-infecting strains. In patients infected with the human immunodeficiency virus (HIV), trimethoprim-sulphamethoxazole provides prophylactic and therapeutic potency against Pneumocystis carinii but at the risk of side effects. Trimethoprim-sulphamethoxazole (TMPSMX) is also used for treatment of pulmonary and disseminated nocardiosis and some forms of Wagener’s granulomatosis, as well as for prophylaxis of spontaneous bacterial peritonitis. Bacterial resistance to trimethoprim-sulphamethoxazole is a rapidly increasing problem and is exacerbated by use of substandard products. In this work, it is aimed to evaluate the physical properties and the dissolution profiles of trimethoprim-sulphamethoxazole tablets produced by ten different manufacturers and are obtained from drug outlets in Addis Ababa. X I I Accordingly, the different tablets were evaluated for physical properties (Diameter, thickness, shape, hardness, friability and disintegration time) and their dissolution profiles were compared by the USP XXVI paddle method. The tablets investigated in this study could roughly be grouped as those, which exhibited, delayed drug release and those, which released the drug contained immediately. The tablets evaluated in this study differed in many of their physical properties. The average weights ranged from 502.41mg (Bactrim) to 709.98mg (Cotrimol), 480mg being the expected strength of the combination. The mean disintegration times ranged from 0.17 (±0) minutes (Cotrimoxazole) to 13.05 (±5.24) minutes (Lagatrim). Nine of the tested products gave an assay value above the lowest limit (93%-107%) specified in the pharmacopoeia. Assay values greater than the upper limit for sulphamethoxazole was obtained with four of the evaluated products. One product gave an assay value greater than the upper limit for both sulphamethoxazole and trimethoprim. Most of the tablets released the drug contained in an increasing fashion from the 5th minute to the 60th minute with varying proportion of increment. Products obtained from Europe released most of the drug within the first 5 to 10 minutes. More than 90 % of trimethoprim is released within 5 minutes from Bactrim and Septrin and with in 10 minutes from Lagatrim and Deprim. While Lagatrim and Septrin released more than 90 % of their Sulphamethoxazole within 10 minutes, Bactrim and Deprim released their Sulphamethoxazole within 20 minutes. However the European X I I I and the non-European products differed significantly in their sulphamethoxazole release. Both products showed a comparable trimethoprim release pattern. All of the tested products released more than 90% of the trimethoprim after one hour, ranging from 92.81%-Cotreich to 111.77%- Septrin. The very long t90% values of Cotreich and Cotrimol (60 & 45minutes respectively) for trimethoprim, the very long t50% & t90% values of Cotreich (38 and >60minutes respectively) for trimethoprim and sulphamethoxazole, and the very long t90% values of Cotreich, Cotrimol and Kanprim (>60 minutes) for sulphamethoxazole indicate that these products could result in lower rate and extent of bioavailability in the body. Similar problems could be encountered with the relatively long t90% values of Cotrimoxazole (45minutes) and Oriprim (40minutes) for Sulphamethoxazole. The smaller amount of sulphamethoxazole and trimethoprim released from products with delayed release could compromise the in vivo efficacy of these tablets.



Antibacterial agents; Co-trimoxazole