The most widely studied drugs for the treatment of abdominal pain are a group of drugs called smooth-muscle relaxants.
The gastrointestinal tract muscle is composed of a type of muscle called smooth muscle. (By contrast, skeletal muscles, such as the biceps, are composed of a type of muscle called striated muscle.) Smooth muscle relaxing drugs reduce the strength of contraction of the smooth muscles but do not affect the contraction of other types of muscles. They are used in IBS with the assumption (not proved) that strong or prolonged contractions of smooth muscles in the intestine-spasms-are the cause of pain in IBS. There are smooth muscle relaxants that are placed under the tongue, like nitroglycerin for treatment of angina, so that they may be absorbed rapidly. Smooth muscle relaxants are approximately 20% more effective than a placebo in reducing abdominal pain. It is not clear if smooth muscle relaxants have a beneficial effect on constipation or diarrhea.
Some commonly used smooth muscle relaxants are hyoscyamine (for example, Levsin) and methscopolamine (for example, Pamine). Other drugs combine smooth muscle relaxants with a sedative (for example, Donnatal), but there is no evidence that the addition of sedatives adds to the efficacy (effectiveness) of the treatment.
The gastrointestinal tract muscle is composed of a type of muscle called smooth muscle. (By contrast, skeletal muscles, such as the biceps, are composed of a type of muscle called striated muscle.) Smooth muscle relaxing drugs reduce the strength of contraction of the smooth muscles but do not affect the contraction of other types of muscles. They are used in IBS with the assumption (not proved) that strong or prolonged contractions of smooth muscles in the intestine-spasms-are the cause of pain in IBS. There are smooth muscle relaxants that are placed under the tongue, like nitroglycerin for treatment of angina, so that they may be absorbed rapidly. Smooth muscle relaxants are approximately 20% more effective than a placebo in reducing abdominal pain. It is not clear if smooth muscle relaxants have a beneficial effect on constipation or diarrhea.
Some commonly used smooth muscle relaxants are hyoscyamine (for example, Levsin) and methscopolamine (for example, Pamine). Other drugs combine smooth muscle relaxants with a sedative (for example, Donnatal), but there is no evidence that the addition of sedatives adds to the efficacy (effectiveness) of the treatment.
