Varying concentrations of octreotide acetate (Sandostatin) and diamorphine hydrochloride were prepared and stored in polypropylene syringes at 37 degrees C in the dark. The solutions were analysed for octreotide acetate content using a validated HPLC method at regular intervals over a 48-h period. The results indicate that octreotide acetate remains stable in the presence of diamorphine hydrochloride at 37 degrees C for 24 h. In addition, the solutions prepared maintained their clarity, with no signs of precipitation upon visual examination under normal light conditions.