Voltammetric Determination of Olopatadine Hydrochloride in Bulk Drug Form and Pharmaceutical Formulations

The voltammetric behavior of olopatadine was investigated at hanging mercury drop electrode using cyclic voltammetry and differential pulse voltammetry. The drug under study exhibited a single, well-defined reduction peak owing to the reduction of carbon-carbon double bond. The electrode and reaction conditions which yielded maximum peak current were established using differential pulse voltammetry. A linear relationship was observed between the peak current and the concentration of olopatadine over the range 1.0 x10 M to 4.0 x10 M. The limits of detection and limits of quantitation were found to be 1.92 ng/mL and 6.34 ng/mL respectively. The proposed method was successfully applied for the determination of olopatadine in pharmaceutical formulations without interference from excipients. INTRODUCTION: Olopatadine belongs to the class of topical antiallergic drugs used for the treatment of allergic conjunctivitis, allergic rhinitis, chronic uriticaria, eczema dermatitis, psoriasis vulgaris and pruritius cutaneous . Its IUPAC name is {(11Z)-11-[3(dimethylamino)propylidene]-6, 11-dihydrodibenzo [b, e]oxepin-2-yl}acetic acid and its structure is shown in Figure 1. It has been demonstrated that olopatadine is clinically superior to other allergic drugs owing to its dual activity as antihistamine and ocular mast cell stabilizer . The efficacy of the drug is evaluated based on its effective diminishing action on the expression of cell adhesion molecules and inflammation markers in conjuctival surface cells in patients with seasonal allergic conjunctivitis . The efficacy and tolerability of olopatadine and cromolyn sodium 2% are compared and it is inferred that olopatadine had significant effect on ocular signs and symptoms of allergic conjuctivitis than cromolyn 2% opthalimic solution . The increased ocular comfort and patient acceptance for olopatadine is mainly due to its restricted interaction with membrane phospholipids thereby inducing less degree of membrane perturbation and release of intracellular constituents . Based on the conjuctival allergen challenge model, the efficacy, safety, optimal concentration and dosage of olopatadine are evaluated in the treatment of allergic conjunctivitis .