Background: Olanzapine (OLZ) is one of most recommended drugs for the treatment of schizophrenia while metformin (MET) is the most commonly used hypoglycemic agent. Aim: Development and validation of two green, sensitive and accurate chromatographic methods for the simultaneous determination of OLZ along with the co-prescribed, MET. Materials & methods: TLC-densitometric method with a developing system consisting of methylene chloride:methanol:ethyl acetate:triethylamine (4:4:5:0.1, by volume) and a reversed-phase (RP)-HPLC method where the chromatographic separation was performed using ethanol:water mixture (50: 50, v/v) as a mobile phase. Results: TLC-densitometric method had linearity over concentration ranges of 160-4000 ng/band for OLZ and 150-4500 ng/band for MET, while RP-HPLC method was linear and validated over concentration range of 300-20000 ng/ml for OLZ and MET. Conclusion: Pharmacokinetic study was successfully performed and suggested the possibility of co-administration of MET with OLZ and their further formulation in one pharmaceutical preparation to enhance patient's compliance.
Keywords: RP-HPLC; TLC densitometry; metformin; olanzapine; pharmacokinetic.