Clarithromycin belongs to semi-synthetic macrolide antibiotic class of drugs that inhibits bacterial protein synthesis.. Our aim of study is to develop a efficient least time consuming and simple spectrophotometric method for the assay of clarithromycin. Comparision of assay of five different brands of clarithromycin (klaricid,klaribact,rithmo,clariteck,E-clark) available in public medical store of Karachi, Pakistan has also been done. The assay is based on the ultraviolet UV absorbance maxima

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... t about 210nm wavelength of mefenamic acid, water is used as solvent. A sample of drug was dissolved in water to produce a solution containing mefenamic acid. Similarly, a sample of ground tablets of different brand were dissolved in water and various dilutions were made. The absorbance of sample preparation was measured at 210nm against the solvent blank and the assay was determined by comparing with the absorbance of available brand. Our results reveals that among all the five brands of clarithromycin (klaricid,klaribact,rithmo,clariteck,E-clark) Klaribact shows highest percentage assay i.e 115.3846%. Klaricid and Claritecl shows percentage assay of 107.693%. Rithmo shows a percent assay of 92.307% while E-clark shows lowest value for percentage assay 84.6153% .Keywords-clarithromycin, assay, UV spectrophotometry INTRODUCTION Clarithromycin is a semi-synthetic macrolide antibiotic. It is bacterial protein synthesis inhibitor. It is better absorbed and acid-stable. It is widely used in regimens of anti-helicobacter pylori (h pylori). The sustained-release (sr) and immediate-release (ir) clarithromycin formulations available on the market. [1] It decreases activity of CYP3A4 enzyme and thus slowly inhibits of coadministered drugs and its own metabolism. Clarithromycin is a broad-spectrum antibiotic and it is widely used for the treatment of upper and lower respiratory tract and many other infections.[2] It interacts with many drugs on the level of CYP3A hepatic and intestinal metabolizing enzymes.[3]Clarithromycin is rapidly and completely absorbed from the gastrointestinal tract (GI). As chlarithromycin undergoese first-pass metabolism, bioavalibility of an oral dose as clarithromycin is fifty% to fifty five% in the systemic circulation. It is widely distributed throughout the body and has an apparent volume of distribution that ranges from 126 to 306 liters. Approximately 22% of an oral dose is recovered as the parent compound, 4% being recovered in the feces with 18% being recovered in the urine. The elimination half-life of clarithromycin is time and dose dependent and ranges from 2.7 to 4.8 hours. The average total body clearance ranges is found to be from 29 to 58 liters/hour and the average renal clearance ranges from 6.7 to 12.8 liters/hours in healthy subjects depending on the the number of doses and dose .[4] clarithromycin has been associated with fetal loss in animals. A study shows a doubling in the frequency of miscarriages among pregnant women using clarithromycin.[5] Clarithromycin acts by binding to the peptidyl transferase region of 23S rRNA and inhibits bacterial protein synthesis. Clarithromycin resistance results from structural changes in the 23S rRNA molecule caused by mutation of the 23S rRNA gene.Transitions of Adenine to guanine at positions 2142 and 2143 are the main 23S rRNA mutations in clarithromycin-resistant isolates[6]. We have already done these types of assay for different drugs [7-10].