Kinetics of 5‐aminosalicylic acid after jejunal instillation in man.

Abstract

The human pharmacokinetics of 5‐aminosalicylic acid (5‐ASA), the active moiety of salazosulphapyridine (SASP), is only known from studies in which rapid absorption has been deliberately avoided. The present investigation demonstrates that pure 5‐ASA is absorbed extremely quickly when given as an instillation in the proximal part of the small bowel, and acetylation follows immediately. The metabolite is excreted very rapidly by the liver in small amounts, while the major part is eliminated renally.

Absorption of 5‐aminosalicylic acid from colon and rectum.

“…The present results indicate that the absorption of 5-ASA is similar in the right and the left parts of the colon. Absorption of 5-ASA has previously been shown to be influenced by the pH of the solution (Bondesen et al, 1984), and the present results confirm, in a direct manner, earlier observations that 5-ASA (given alone or as sulphasalazine) is poorly absorbed in the colon compared with the small intestine (Schroder & Cambell, 1972;Nielsen & Bondesen, 1983). In the latter study instillation of 250 mg 5-ASA resulted in plasma concentrations of more than 30 ,umol 1V1 and fast urinary excretion of more than 45% of the dose.…”

“…The median plasma concentrations (Figure 1) are in both situations low for 5-ASA compared with intrajejunal instillation (Nielsen & Bondesen, 1983). The metabolite was uniformly found to be 4 to 10 times higher.…”

“…Thus, in the present study the total recovery of 5-ASA was lower than expected. Neither incomplete sampling (as reflected in satisfactory urinary and faecal outputs) nor loss of stability of the 5-ASA in the solutions (personal observation) may be held responsible, but incomplete recovery of 5-ASA has been observed earlier (Nielsen & Bondesen, 1983;Bondesen et al, 1984Bondesen et al, , 1986van Hogezand et al, 1985), and might partly be explained by the existence of non-detected metabolites in faeces (Bondesen et al, 1984;van Hogezand et al, 1985). The study of other possible metabolites of 5-ASA merits further investigations in the light of 5-ASA being shown to have radical scavenger properties (AhnfeldtR0nne & Nielsen, 1987).…”

“…5-ASA is absorbed rapidly and extensively from the small intestine (Nielsen & Bondesen, 1983) if given orally, but little is known about the absorption from the colon. Thus, acidic and neutral 5-ASA solution given rectally resulted in urinary recoveries of 35% and 21%, respectively (Bondesen et al, 1984), but more detailed studies with respect to the absorption pattern as such were not performed.…”

The effect of therapeutic drugs used in inflammatory bowel disease on the incidence and growth of colonic cancer in the dimethylhydrazine rat model

“…However, 5-ASA taken orally is absorbed rapidly from the small intestine (Schroder & Campbell, 1972); hence the amount of 5-ASA reaching the colon may be inadequate for therapy (Nielsen & Bondesen, 1983). To overcome this difficulty, olsalazine sodium (containing two molecules of 5-ASA joined by an azo bond), has been developed.…”