Net cash proceeds from the transaction are expected to be approximately 135 million pounds and will be returned to shareholders during 2012.
The sale is the latest move by GSK to fine-tune its consumer healthcare business and follows the divestment of other over-the-counter (OTC) brands in North America and Europe.
The brands being sold generated sales of around 60 million pounds in 2011. They include the painkiller Solpadeine and anti-stomach acid drug Zantac.
The net profit realised on the disposal in 2012 - after deducting transaction costs and a profit deferral of some 25 million pre-tax because Aspen is a GSK associate - is expected to be 105 million before tax, or 90 million after tax.
GSK added it continued to plan to sell its OTC weight-loss pill Alli. This process has been delayed due to supply problems at a Roche
The Swiss company manufactures the active ingredient, orlistat, which is also the active substance in Roche's prescription-only drug Xenical. Alli is a low-dose version of Xenical.
GSK first announced in February 2011 that it planned to dispose of non-core brands sold primarily in North America and Europe and representing about 10 percent of its consumer health portfolio, in order to focus on priority brands and emerging markets.
($1 = 0.6226 British pounds)
(Reporting by Ben Hirschler; Editing by Kate Kelland and Mark Potter)