Intestinal absorption of Mn-mesoporphyrin in a small bowel sac system: effect of oleic acid.
OBJECTIVE
The authors investigated the effect of oleic acid (cis-9-octadecenoic acid) (OA), a lipidic carrier, on the intestinal absorption rate and T1 relaxation time of manganese (III) mesoporphyrin (Mn-mesoporphyrin), a prototype hepatobiliary contrast agent for magnetic resonance imaging.


METHODS
Mn-mesoporphyrin was formulated with OA at various concentrations. Small bowel sacs were created in 36 rats and filled with complexed and free Mn-mesoporphyrin. Intestinal absorption of Mn-mesoporphyrin was measured with spectrophotometry at 364 nm. T1 relaxation times were measured in samples of Mn-mesoporphyrin solutions, bowel wall, liver, and bile.


RESULTS
Absorption rates ranged from 4.2%/cm2/h to 13%/cm2/h. Absorption was greatest (13%/cm2/h) when a combination of 1 mmol/L Mn-mesoporphyrin and 26.5 mmol/L OA was used. The T1 of bile decreased from 2,480 to 248 msec (maximum decrease) in rats that received Mn-mesoporphyrin.


CONCLUSIONS
Mn-mesoporphyrin is absorbed from the small bowel in both the lipid-associated and free form, resulting in substantial shortening of the T1 in bile.
von Ingersleben
G
G
Department of Radiology, University of Washington, School of Medicine, Seattle, USA.
Schmiedl
U P
UP
Dong
P
P
Nelson
J A
JA
Starr
F
F
Ho
R J
RJ
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000378:metabolism*; D004337:Drug Carriers; D005260:Female; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000502:physiology*; D008081:Liposomes; D008297:Male; D008652:Mesoporphyrins / Q000008:administration & dosage / Q000378:metabolism*; D019301:Oleic Acid; D051381:Rats; D017207:Rats, Sprague-Dawley
D003287:Contrast Media; D004337:Drug Carriers; D008081:Liposomes; D008652:Mesoporphyrins; C067090:manganese mesoporphyrin; D019301:Oleic Acid