[Treatment of spasms of visceral smooth muscles]

A lot of pathophysiological factors can cause increased activation of smooth muscle contractile mechanisms resulting in long-lasting contractions-spasms. They significantly increase the intercellular concentration of calcium ions and/or increase the affinity of thin contractile filaments for them. The most frequently used drugs in the therapy of visceral smooth muscle spasms are substances that relax smooth muscles (with antimuscarinic activity/atropine-like/or with non-specific activity/papaverine-like direct spasmolytics) and analgesics (opioids or nonsteroid antiinflammatory drugs-NSAID). In the treatment of biliary and renal colics NSAIDs for parenteral use were equally or more efficient than spasmolytics or opioid analgesics. Organic nitrates relax smooth muscles efficiently, but this effect is short-lasting due to their rapid liver metabolism. Experiences with other drugs that could be useful in spastic visceral conditions are still scarce (calcium channel blockers, botulinum toxin, metoclopramide etc). Due to diversity of mechanisms of action of spasmogenic factors, further investigations are directed to discovery of more efficient and more selective drugs than these currently used.