Formulation and evaluation of extended-release tablets of an antidepressant drug Venlafaxine HCl

Abstract

Oral drug delivery is the most desirable and preferred method of administering therapeutic agents for their systemic effects. A dosage form that allows at least a twofold reduction in dosage frequency as compared to that drug presented as an immediate-release (conventional) dosage form is extended-release dosage form. It includes controlled-release, sustained-release, and long-acting drug products. The mechanism of action of venlafaxine HCl in humans is believed to be associated with its potentiation of neurotransmitter activity in the CNS. Venlafaxine and its active metabolite, O-Desmethylvenlafaxine (ODV), inhibit the reuptake of both serotonin and norepinephrine. In the present work, an attempt has been made to develop extended-release (ER) coated tablets of Venlafaxine HCl by selecting different grades of polymers, Hydroxypropyl methyl cellulose, ethyl cellulose and xanthan gum. These are used as retarding polymers to extend the drug release. All the formulations were prepared by wet granulation method and compressed using 9.8 mm punches on 16 stations rotary tablet punching machine. The blend of all the formulations showed poor flow properties. In order to improve flow, higher % of glidant was used. The coating material used was ethylcellulose aqueous dispersion (Aquacoat ECD 30). The prepared ER coated tablets of Venlafaxine HCl showed good post-compression parameters. They passed all the evaluation tests as per USP limits. Among all the formulations, F7 showed maximum % drug release, i.e., 99 % in 24 hours hence it is considered as optimised formulation. The optimised formulation compared with marketed tablets.