The invention relates to solid oral pharmaceutical compositions in the form of pellets, mini- tablets, tablets, or capsules, comprising an optionally substituted 2-(pyridylmethylsulfinyl)-1H- benzimidazole, for example esomeprazole, and carrageenan, and optionally one or more excipients. Surprisingly, it has been found that these compositions are stable and rapidly release the active ingredient. The pellets or mini-tablets may be coated as such, or filled in capsules or pressed into tablets, with a polymer, which dissolves only at a pH value of 5 or higher, optionally over a stabilizing intermediate layer.