Shares of pharma companies were outperforming in an otherwise weak market session as rising demand for medicines amid rising Coronavirus infections in country led to investors buying shares of pharma companies.The gauge of pharma shares on the National Stock Exchange rose 1.4 per cent massively outperforming the Nifty 50 index which was down 3.58 per cent.Rising Covid-19 cases in the country is leading to higher demand for medicines which is driving up the share prices of drugmakers, analysts said.Reports of the government imposing ban on export of anti-viral drug Remdesivir owing to shortage also led to buying interest in pharma shares.India has banned export of the anti-viral drug Remdesivir amid a surge in COVID-19 cases in the country. In an order, the government said it has banned export of Remdesivir injection and Remdesivir active pharmaceutical ingredients (API) till the pandemic situation in the country stabilises.Cipla was top gainer among the pharma shares. The stock rose as much as 6.45 per cent to hit an all-time high of Rs 940 on the National Stock Exchange.Divi’s Labs, Dr Reddy’s Labs, Torrent Pharma, Cadila Healthcare, Ipca Labs, Laurus Labs and Alkem Labs were also trading with a positive bias.