Assessment of the Airway Smooth Muscle Relaxant Effect of Drotaverine

Zoltán Patai, A. Guttman, Endre G. Mikus

Research output: Contribution to journalArticle


Background: Drotaverine, a type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitor, blocks the degradation of 3',5'-cyclic adenosine monophosphate. However, published receptor binding data showed that drotaverin also binds to the L-Type voltage-operated calcium channel (L-VOCC). Based on these molecular mechanisms of action, a direct and indirect (by blocking the constrictor response) relaxant effect on airway smooth muscle can be predicted, which has not yet been assessed. Summary: Accordingly, drotaverine and reference agents were tested both on the histamine-, methacholine-, or KCl-induced contraction response and on precontracted Guinea pig tracheal preparations. It was found that drotaverine not only relaxed the precontracted tracheal preparations but also decreased mediator-induced contraction. These effects of drotaverine were concentration dependent, with a significantly higher potency on the KCl-induced response, than on either the histamine or methacholine induced one. A similar result was noted for nifedipine. The PDE inhibitor, theophylline, also relaxed the precontracted preparations but was ineffective on the mediator-induced contraction in a physiologically relevant concentration range. Moreover, theophylline did not show selectivity and was the least potent relaxant among the 3 tested molecules. Key Message: These results show that drotaverine is a more potent airway smooth muscle relaxant molecule than theophylline. This enhanced potency on relaxation and inhibition of the constrictor response, at least partly, may be explained by the combined L-VOCC blocking and PDE inhibitory potential of drotaverine.

Original languageEnglish
Pages (from-to)163-169
Number of pages7
Issue number3-4
Publication statusPublished - Feb 1 2018



  • Airway smooth muscle relaxant
  • Ca antagonist
  • L-Type voltage-operated Ca channel
  • Phosphodiesterase inhibition

ASJC Scopus subject areas

  • Pharmacology

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