OXYTOCIN AND DESAMINO-OXYTOCIN TABLETS ARE NOT STABLE UNDER SIMULATEDTROPICAL CONDITIONS

Objectives. This study is part: of a programme on reduction of postpar tum haemorrhage. Buccal oxytocin and desamino-oxytocin administration with a favourable effect on both blood loss and maternal morbidity and mortality were regarded as possible treatments for use in tropical co untries. The stability of buccal oxytocin and desamino-oxytocin under tropical conditions was unknown and therefore tested in this study. St udy methods. The 'experimental shelf lives' of buccal oxytocin and des amino-oxytocin were examined by exposing the tablets to seven artifici ally controlled conditions. Samples were analysed by high performance liquid chromatography to determine the content of oxytocin and desamin o-oxytocin at nine different times during the period of 1 year. Result s. Oxytocin and desamino-oxytocin are fairly stable under refrigeratio n, Instability for both drugs was detectable after 20 weeks' storage u nder humid conditions, independent of temperature. Desamino-oxytocin i s more sensitive to light exposure; its concentration declines to 55.6 % of the stated amount after 1 year of exposure to light compared to 8 5% in the case of oxytocin. Oxytocin packaged as supplied by the manuf acturer were stable for 21 weeks when exposed to simulated humid (75% relative humidity) conditions. At 40 degrees C and 25% relative humidi ty there is no difference in stability between tablets in sealed alumi nium packs as supplied by the manufacturer and unpackaged tablets.Conc lusions. Tropical conditions make oxytocin and desamino-oxytocin table ts unstable, with humidity as the most adverse factor. The oxytocin ta blets were partially protected from the harmful effect of humidity by sealed aluminium package.