Investec reiterated a 'buy' rating and price target of 647p for pharmaceuticals firm BTG after reappraising its key product Varithena.The bank said investors overreacted to concerns over BTG's earning profile, in particular the varicose vein treatment Varithena."After interviewing physicians and market access experts to reappraise Varithena, we consider the product to be better positioned than the market is pricing in, albeit it will take time to overcome specific hurdles."Investec viewed BTG's management's FY16 revenue guidance of $15m-$25m as possible, but said it needs to see a meaningful improvement in physician reordering.Share in BTG fell 2.04% to 624.50p at 15:07 on Monday.