Profit excluding certain costs rose to 19.8 pence a share, which topped the 17.9-pence average of analyst estimates.
The last year-over-year increase in earnings, using that measure, was in the third quarter of 2013. Glaxo completed a three-part transaction with Novartis during the first quarter of 2015.
The UK company sold some cancer medicines to Novartis and bought the Swiss drugmaker’s vaccines business, while forging a consumer-health joint venture. Shares of Glaxo rose over 2% at one stage in London.
The stock has dropped around 6.5% in the last year. The drugmaker said it expects 2016 earnings-per-share growth to be between 10% and 12% on a constant-exchange rate basis. Profit rose 8% in the quarter.
The results may help vindicate the claims of outgoing chief executive Andrew Witty that the drugmaker is on the road to recovery, with demand for new respiratory and HIV medicines offsetting a decline in sales of ageing lung treatment Advair.
Mr Witty, who bows out in 2017, has been under pressure as profits have flagged and investors have questioned his focus on consumer health products, which range from headache pills to toothpaste, leading to calls for a break-up of GSK.