this invention relates to a 24 hour extended release dosage formulation and unit dosage form thereof of venlafaxine hydrochloride , an antidepressant , which provides better control of blood plasma levels than conventional tablet formulations which must be administered two or more times a day and further provides a lower incidence of nausea and vomiting than the conventional tablets . more particularly , the invention comprises an extended release formulation of venlafaxine hydrochloride comprising a therapeutically effective amount of venlafaxine hydrochloride in spheroids comprised of venlafaxine hydrochloride , microcrystalline cellulose and , optionally , hydroxypropylmethylcellulose coated with a mixture of ethyl cellulose and hydroxypropylmethylcellulose .