Cisapride (CIS) is a gastrointestinal prokinetic agent. It has been associated with rare, but serious cardiac side effects.However, it does not affect psychomotor functions or induce central depressant adverse effects. As liquid formulations arerequired in a number of cases, an oral suspension of CIS was developed from CIS tablets. The objective of this study was toinvestigate the effect of hydroxypropyl- -cyclodextrin (HP- -CD) on the stability of CIS in oral suspension with an ultimateaim to formulate a more stable CIS oral suspension. Six batches of CIS oral suspensions, namely, 0 (control), 0.3, 1.6, and 3%HP- -CD containing formulations were prepared. They were stored at 5°C and 30°C. The amounts of CIS in the suspensionswere determined by a validated stability-indicating HPLC-DAD method. The stability was assessed based on the 90%remaining. The changes in the amounts of CIS over time were statistically analyzed by ANOVA and ANCOVA. At 5°C, HP- -CD had no significant effect on the stability of CIS. CIS in all four formulations was stable for at least 12.5 months. At 30°C,HP- -CD affected the stability of CIS. CIS was most stable in 0.3% HP- -CD containing formulation with the observed t90 ofapproximately 11 months as compared to 7 months in control formulation.