Validated Analytical Spectrofluorimetric Method For Quantitation of Diphenhydramine Hcl in Commercial Dosage Forms - Validated Analytical Spectrofluorimetric Method For Quantitation of Diphenhydramine Hcl in Commercial Dosage Forms - Open Access Pub

Diphenhydramine HClis a weakly fluorescent drug having tertiary amine group forming ion pair complex with eosin Y in dichloromethane at pH 5 in disodium hydrogen phosphate-citric acid buffer solution. The complex formation was the basis for the development of new analytical method for determination of active diphenhydramine in pharmaceutical formulations. The stoichiometric ratio between diphenhydramine and eosin Y was studied by mole ratio method and found to be 2:1. The ion-pair complex showed maximum fluorescence emission intensity at 554 nm with excitation at 259 nm. The linear dynamic range was obtained in the concentration range of 2-22 μg mL-1 with a linear equation of FI = 0.361 + 13.675 C. The apparent Gibb’s free energy (ΔGo) was calculated and found to be -80.783 KJ mol-1, confirmed the feasibility of the reaction. The proposed method was successfully applied to the determination of diphenhydramine HCl in pharmaceutical formulations and in good agreement with the reference method. DOI10.14302/issn.2377-2549.jndc-18-2220 Diphenhydramine hydrochloride is chemically known as 2-(Diphenylmethoxy)-N,N-dimethylethylamine hydrochloride (CAS: 147-24-0; M.W.: 291.82). Figure 1 represents 3d structure of diphenhydramine. It belongs to the class of antihistamine, competitively blocks the effects of histamine at H1-receptor sites, and has atropine-like, antipruritic and sedative effects 1. It is approved to treat the symptoms of motion sickness, sneezing, running nose, watery eyes, hives, skin rash, itching and other cold or allergy symptoms. The usual recommended dose of the active drug for patients is 25-50 mg for every 4-6 hr, not to exceed 300 mg per 24 hr. The assay of diphenhydramine hydrochloride is described in British Pharmacopoeia 2, United States Pharmacopeia 3 and Indian Pharmacopoeia 4 based on potentiometric titration, high performance liquid chromatographic method and volumetric titration, respectively. Here, the developed method is simple and more convenient based on spectrofluorimetric method. The drug is important and hence the safety, quality, quantity and purity of drug are on high demand 5. In view of the great importance of the drug in terms of its optimum oral dose and wide use, it is important to analyze the drug in pharmaceutical preparations. With increasing regulatory strictness and owing to the reason of quality control, various analytical methods have been developed in pure and dosage forms including titrimetry 6, high performance thin layer chromatography 7, capillary electrophoresis 8, gas chromatography 9, high performance