Influence of neutron activation factors on the physico-chemical propertiesof suppositories and their excipients

The effect of the neutron activation factors, i.e., admixture of samarium o xide (Sm2O3) and irradiation time, on the physico-chemical properties of th e raw materials and the in vitro dissolution and disintegration of hydrophi lic and lipophilic suppositories was investigated. It was possible to expos e the pure bases and the model drugs (5-aminosalicylic acid [5-ASA] and rop ivacaine hydrochloride) to 1 min of neutron irradiation in a flux of 1.1.10 (13) n cm(-2) s(-1). The dissolution and disintegration of the correspondin g suppositories showed that the physico-chemical properties and the fractio n of incorporated drug together with the lipophilic/hydrophilic nature of t he base were important factors. Sm2O3 increased the disintegration time of hydrophilic suppositories containing 5-ASA, while the dissolution of both d rugs from these formulations remained unchanged. Sm2O3 did not alter the di sintegration time of the lipophilic formulations, but it reduced the dissol ution of both drugs from these suppositories. Irradiation induced different behaviour in the different bases. (C) 1999 Elsevier Science B.V. All right s reserved.