Correlation of absorption of sulfamethazine boluses with dissolution using a new dissolution apparatus for veterinary tablets.

A rotating-basket apparatus for dissolution testing of veterinary bolus tablets was designed and constructed. Sulfamethazine boluses containing different disintegrating agents were evaluated in vitro and by blood level data following administration to cattle. The dissolution t50 and various pharmacokinetic parameters showed directly compressible starch and carboxymethylstarch to be the most effective disintegrants in the concentrations employed while magnesium aluminum silicate and microcrystalline cellulose were about equal but less effective than the previous disintegrants. A bolus formulation containing no disintegrant gave even less satisfactory results. A correlation was established between the dissolution t50 and the time to peak plasma level and also between the t50 and the area under the plasma-time curve for the first 36 hr.