A Rapid Derivative Spectrophotometric Method for Simultaneous Determination of Naphazoline and Antazoline in Eye Drops
Chemical and pharmaceutical bulletin
Naphazoline hydrochloride (0.05%), a vasoconstrictor and decongestant, has been marketed as combination drug with antazoline phosphate (0.5%), an antihistamine, in eye drops. The combination is used to relieve redness, puffiness, itchy and watering eyes associated with colds, allergics or eye irritations. Literature survey showed few old reports on the simultaneous spectrophotometric analysis of naphazoline and antazoline in drops based on two-component spectrophotometric methods using
... hods using orthogonal functions or least squares. 1,2) Gas chromatographic and high performance liquid chromatographic methods were also reported for determination of naphazoline and antazoline in pharmaceutical preparations. 3-5) These methods are complicated and need the expensive instruments. No official procedure is given in wellknown pharmacopeias for simultaneous determination of naphazoline and antazoline. Direct UV-visible spectrophotometric method is not suitable for simultaneous determination of naphazoline and antazoline due to spectral overlapping. Derivative spectrophotometry offers a powerful tool for quantitative analysis of multi-component mixtures, especially in the field of pharmaceutical analysis to overcome some problems by interferences, due to substances other than analytes.                 This report describes a simple, sensitive and rapid procedure for simultaneous determination of naphazoline hydrochloride and antazoline phosphate in eye drops based on derivative spectrophotometry. Experimental Chemicals Naphazoline hydrochloride form LOBA Feinchemie AG (Austria) and antazoline phosphate from SIMS S. P. A. (Milano, Italy) were donated by Sina-Darou Pharmaceutical Company (Tehran, Iran). Methanol was of analytical grade and obtained from Merck (Darmstadt, Germany). Apparatus Absorption and derivative spectra were recorded in 1 cm quartz cells using a Shimadzu UV-160 double beam UV-visible spectrophotometer (Shimadzu, Kyoto, Japan) with a fixed bandwidth (2 nm) and data processing capacity. The zero-order absorption spectra were recorded over the wavelength range 200-400 nm against a solvent blank. The derivative spectra were obtained over the same range at different slit width (Dl). The ordinate, maximum and minimum, was adjusted to the magnitude of derivative values. A zero-crossing first-derivative spectrophotometric method is applied for the simultaneous determination of naphazoline hydrochloride and antazoline phosphate in eye drops. The measurements were carried out at wavelengths of 225 and 252 nm for naphazoline hydrochloride and antazoline phosphate, respectively. The method was found to be linear (r 2 Ͼ0.999) in the range of 0.2-1 m mg/ml for naphazoline hydrochloride in the presence of 5 m mg/ml antazoline phosphate at 225 nm. The same linear correlation (r 2 Ͼ0.999) was obtained in the range of 1-10 m mg/ml of antazoline phosphate in the presence of 0.5 m mg/ml of naphazoline hydrochloride at 252 nm. The limit of determination was 0.2 m mg/ml and 1 m mg/ml for naphazoline hydrochloride and antazoline phosphate, respectively. The method was successfully used for simultaneous analysis of naphazoline hydrochloride and antazoline phosphate in eye drops without any interference from excipients and prior separation before analysis.