Abstract
Introduction: Pilocarpine, a natural alkaloid that can be obtained from species of Pilocarpus, has been used to treat glaucoma, ocular hypertension and xerostomia. The development and validation methods for analysis of pilocarpine and its degradation products are quite challenging since the physicochemical properties between them are relative small.
Methods: Analytical tests in HPLC-DAD were performed and 13 different conditions were take into acount, employing three columns (silica based C18, modified-silica cyanopropyl and Zic-HILIC), two buffer solutions, two organic solvents, pH ranging from 5.1 to 5.45, three temperatures and flow rate from 0.8 to 2.0 mL.min-1, in RP or HILIC. The chromatographic assays for pilocarpine hydrochloride in aqueous solution allowed to establish the best chromatographic parameters in terms of signal symmetry and retention as well as to separate pilocarpine from its degradation products with great selectivity, efficiency and resolution. It was possible to validate a new method to dosage pilocarpine hydrochloride in tablets using a modified-silica cyanopropyl column, mobile phase in isocratic mode with mixture of acetonitrile/ potassium dihydrogen phosphate buffer 10 mM (60:40, v/v), pH 5.30, oven temperature of 50 oC and flow rate of 1.0 mL.min-1.
Conclusion: The precision, accuracy, linearity, robustness, recovery, short retention time, isocratic elution mode, quantification (250 ng.mL-1) and identification (75 ng.mL-1) limits allowed establishing a routine estimation for pilocarpine in tablets. The pilocarpine hydrochloride content it was in the range as specified by the Salagen® producer (4.81 ± 0.07 mg/ tablet, 96.16 ± 1.33%) and by the formulation in carbomer 940® + chitosan tablets (4.80 ± 0.02 mg/ tablet, 95.99 ± 0.49%) and in sodium carboxymethylcellulose + chitosan tablets (4.95 ± 0.04 mg/ tablet, 99.08 ± 0.79%).
Keywords: Pilocarpine, pharmaceutical analysis, tablets, HPLC-DAD, cyanopropyl column.
Graphical Abstract
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