I took the liberty of expanding your question for the purposes of this column.
Generally, compounding of antibiotic rectal suppository forms is not recommended because of the lack of data to support their use. Indeed, their pharmacokinetics may differ from those of orally administered medications, owing to reduced hepatic first-pass metabolism. However, a particular study suggests a possible use for this route of administration: ?The rectal route of antibiotic administration might be used effectively when other routes of administration are inadequate or unsuitable. With the use of various adjuvants, the rectal route can provide satisfactory pharmacokinetics and acceptable local tolerance? (Bergogne-Berezin E, Bryskier A. J Antimicrob Chemother. 1999).
Another study suggested better patient acceptance of a vaginal suppository containing antibiotic than a gel-based formulation of the same antibiotic (Broumas AG, Basara LA. Adv Ther. 2000). Because it was a study of patient acceptance and used a dose form (?ovule?) not available in the United States, no information was gleaned regarding the compounding of a suppository. The specific formulation for compounding a suppository form of a particular antibiotic must be based on the antibiotic?s physical and chemical characteristics (melting point, decomposition profile, etc) and bioavailability data, and on release-rate studies of the particular drug from the particular base intended. For example, if a particular antibiotic is heat labile above body temperature, theobroma oil might be a useful base; moreover, shaved theobroma oil can form the basis for a cold-compressed suppository. If sufficient information to form a conclusion supporting the use of the dosage form is not available, the pharmacist should rely on commercially available dosage forms with proven bioavailability.