Pharmacological basis for the medicinal use of psyllium husk (Ispaghula) in constipation and diarrhea

Dig Dis Sci. 2011 May;56(5):1460-71. doi: 10.1007/s10620-010-1466-0. Epub 2010 Nov 17.


Background: The objective of this study was to determine the pharmacological basis of the medicinal use of psyllium husk (Ispaghula) in gastrointestinal motility disorders.

Methods: In-vivo studies were conducted on mice, and isolated rabbit jejunum and guinea-pig ileum were used in in-vitro experiments.

Results: The crude extract of Ispaghula (Po.Cr) had a laxative effect in mice at 100 and 300 mg/kg, which was partially sensitive to atropine or SB203186 (5-HT(4) antagonist). At higher doses (500 and 1,000 mg/kg), Po.Cr had antisecretory and antidiarrheal activity. In guinea-pig ileum, Po.Cr (1-10 mg/ml) had a stimulatory effect, which was partially sensitive to atropine or SB203186. In rabbit jejunum, Po.Cr had a partially atropine-sensitive stimulatory effect followed by relaxation at 10 mg/ml. The relaxation was inhibited by the presence of L-NAME, a nitric oxide (NO) synthase inhibitor, or methylene blue, a guanylyl cyclase inhibitor. Similarly, the relaxant effect of Po.Cr on K(+) (80 mM)-induced contractions, was attenuated in the presence of L-NAME or methylene blue. Activity-directed fractionation of Po.Cr revealed that the gut stimulatory and inhibitory constituents were widely distributed in the aqueous and organic fractions.

Conclusion: This study demonstrates that Ispaghula has a gut-stimulatory effect, mediated partially by muscarinic and 5-HT(4) receptor activation, which may complement the laxative effect of its fiber content, and a gut-inhibitory activity possibly mediated by blockade of Ca(2+) channels and activation of NO-cyclic guanosine monophosphate pathways. This may explain its medicinal use in diarrhea. It is, perhaps, also intended by nature to offset an excessive stimulant effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arginine Vasopressin / analogs & derivatives
  • Arginine Vasopressin / drug effects
  • Constipation / drug therapy*
  • Diarrhea / drug therapy*
  • Female
  • Guinea Pigs
  • Jejunum / drug effects
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology
  • Psyllium / pharmacology*
  • Rabbits
  • Verapamil / pharmacology


  • Plant Extracts
  • argipressin, beta-mercapto(beta,beta)-cyclopentamethylenepropionic acid(1)-Ile(2,4)-
  • Arginine Vasopressin
  • Psyllium
  • Verapamil