ABSTRACT:
Duloxetine is chemically N – methyl-3-(1-naphthyloxy)-3-(thiophen-2-yl)-propan-1-amine, is a balanced and potent reuptake inhibitor of serotonin and norepinephrine. Methylcobalamin is chemically Methyl-5, 6-dimethyl benzimidazolylcobalamin, is one of the two coenzyme forms of vitamin B12 in the enzyme methionine synthase which functions to transfer methyl groups for the regeneration of methionine from homocysteine. The combination of these two drugs is used in relieving the complications of diabetic peripheral neuropathy. The aim of the current study is to develop a modified simultaneous spectrophotometric determination (Q-Absorbance ratio method) of duloxetine and methylcobalaminin bulk and pharmaceutical dosage form (tablet and capsule). Duloxetine has exhibited maximum absorbance at 288 nm and it transparent at 326 nm. The isobestic point was selected at 254 nm as both the drugs recorded maximum absorbance, also it was found wavelength difference is higher when compared to 278 nm. In replicate analysis (n=5) of the two drugs by the proposed UV method, the % label claim and % RSD of duloxetine and methylcobalamin were appreciably low for tablet and capsule formulation. The correlation between absorbance and concentration in terms of correlation coefficient (r) was found to be 0.9956 and 0.9979. The validation parameters observed proved that this method simple, sensitive, accurate and precise. Hence, the developed new method can be employed for the routine analysis of these two drugs in combined dosage forms.