Ecofriendly chromatographic methods for determination of co-prescribed drugs, olanzapine and metformin, in rat plasma.

Olanzapine (OLZ) is one of most recommended drugs for the treatment of schizophrenia while metformin (MET) is the most commonly used hypoglycemic agent. Development and validation of two green, sensitive and accurate chromatographic methods for the simultaneous determination of OLZ along with the co-prescribed, MET. 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. 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. 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.