Comparative Determination of Chlorpromazine in Pharmaceutical Injectable Veterinary and Human Formulations by Spectrophotometric and High Performance Liquid Chromatographic Methods
Keywords:Chlorpromazine, colorimetric, HPLC, pharmaceutical preparation, phenothiazine tranquilizer
Background: Chlorpromazine (CPZ) is a phenothiazine tranquilizer used in humans and animals. Rapid determination
of the drug in pharmaceutical preparations is often needed. The aim of the study was to further examine and ascertain
asimple spectrophotometric method in comparison with a high performance liquid chromatographic (HPLC) method
for the determination of CPZ concentrations in injectable pharmaceutical formulations used in man and animals.
Methods: Concentrations of CPZ in injectable pharmaceutical formulations for human and veterinary uses were
determined by a modified spectrophotometric method and by an HPLC method with appropriate standard calibration
curves. The spectrophotometric method of CPZ determinationwas conducted by diluting 0.1 ml of the veterinary
(5%) or 0.3 ml of human (0.5%) formulations to 200 ml of 0.1N sulfuric acid. Four ml of the diluted CPZ samples or
the standard solutions were mixed with 2 ml of 50% sulfuric acid. Then an aliquot of 0.2 ml of 2% ferric nitrate was
added to the mixture. After 15 minutes, the absorbance was measured at 530 nm against water and vehicle blanks
using a spectrophotometer. The HPLC method applied in the present study consisted of reversed phase gradient
chromatography with a C18 column and the eluent was (A) 50 mmol NaH2PO4, pH 2.5 and (B) acetonitrile - 50
mmol NaH2PO4, pH 2.5 (60:40 v/v), flow rate at 1 ml/min, with a gradient of 15-55% B in 10 min, to 100% B in
20 min, and 280-nm UV detection. From the calibration curves of CPZ standards, the following were calculated:
Limit of detection limit (LOD) = 3.3 x SD/slope; Limit of quantitation (LOQ) = 10 x SD/slope, where SD is the
standard deviation of response of CPZ concentrations of the calibration curves.Linear regression analysis and related
coefficients of correlations were applied on the calibration curves. Results: The calibration curves of CPZ against
water or vehicle blanks as determined by the spectrophotometric method or by the HPLC method were linear with
strong correlations (r = and / or >0.99). Based on the calibration curves, limit of detection and limit of quantitation the
spectrophotometric method were comparable to those of the HPLC one. The contents CPZ in human and veterinary
injectable formulations as determined by the spectrophotometricmethod were in accordance (100.6% and 102%,
respectively)to the concentrations claimed on the labels of the formulations.
Conclusion: The present results introduce a simple spectrophotometric method that could be used for routine
measurement of CPZ concentrations in pharmaceutical formulations, with the added benefits of linearity, precision
and cost effectiveness.
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