Pregnancy Category D

Uses. This drug became available in the 1950s as an alternative to barbiturates. It works as a sleep aid and muscle relaxant, the latter property perhaps a result of the drug's antianxiety property rather than a direct effect. Mepro-bamate's muscle relaxant action improved breathing in experimental treatment of tetanus. A person's appetite may get better with the drug, but again as a result of anxiety reduction rather than direct appetite stimulation—an agricultural experiment using meprobamate to encourage weight gain in chickens was unsuccessful. The drug may lessen petit mal epilepsy seizures but worsen grand mal seizures. Meprobamate has also been used against neuroses and attention deficit hyperactivity disorder (ADHD), against a type of muscular discomfort called myofascial pain, and as part of therapy treating skin lesions brought on by worry. Meprobamate has helped improve stubborn cases of gastrointestinal afflictions, which may have a component of stress. An experiment showed that persons using the drug can fool a lie detector test.

Meprobamate became perhaps the most highly regarded tranquilizer in the United States. In some research during that era of meprobamate's popularity the question was no longer whether the drug worked but how much better it worked for some groups of people (married, widowed, overweight) than for others. Nonetheless, meprobamate's medical uses declined after benzodiaze-pine class depressants became available. In retrospect skepticism arose about whether meprobamate had ever been as beneficial as its reputation indicated. Some experts decided that its muscle relaxant and antianxiety actions were no stronger than those inherent to any sedative. One team of scientific investigators concluded that in some circumstances patients' therapeutic reactions to meprobamate were "no worse than to placebo"—faint praise indeed. Trans formation of the medical establishment's attitude toward meprobamate is, however, a social history study beyond the scope of this book.

Drawbacks. Meprobamate can cause euphoria and, even though it is a depressant, can have stimulant actions in some circumstances—indeed, mania has been known to occur after a dose. Unwanted actions include headache, vision trouble, nausea, diarrhea, dizziness, slurred speech, burning or prickling sensations, rashes or other skin outbreaks, severely reduced body temperature, low blood pressure, accelerated heartbeat, fainting, and difficulty in moving around. Users should avoid operating dangerous devices such as automobiles. Tests have measured worsened learning ability, physical coordination, and reaction time while a person is under meprobamate's influence— although such problems are not found with all tests designed to detect them.

During meprobamate's medical popularity in the 1960s military tests explored the drug's influence on performance under stress. One test series simulated aircraft pilot situations involving simultaneous tracking of locations in two dimensions, monitoring changes in audio signals, and decoding messages—while exposed to reduced oxygen levels simulating altitudes up to 17,000 feet. In another test series civilian experimenters adapted techniques used by the Swedish air force in a task where persons had to push buttons, pull levers, and press pedals in response to lights and sounds. Investigators basically found that the drug acted as a distraction; people could perform adequately when low levels of skill were required, but as more and more tasks had to be accomplished at higher speeds, the drug interfered with performance. Such a result was hardly surprising, although details may have been relevant to military decision makers.

In mice the drug promotes amnesia. Experimenters gave the drug to rats for 12 weeks and found it reduced the amount of DNA in brain cells. Meprobamate may aggravate porphyria, a blood chemistry disorder that can make people violent and sensitive to light. Although some persons use the drug for years without untoward effect, case reports note uncommon instances where the drug may have caused serious and sometimes fatal blood diseases such as agranulocytosis and aplastic anemia.

One disquieting effect of meprobamate is its ability to produce flat brainwave readings, which could cause medical personnel to cease vital treatment in a mistaken belief that the patient has died.

Abuse factors. Meprobamate's abuse potential has been described as similar to benzodiazepine depressants. Dependence on meprobamate can develop if excessive amounts are routinely used. Abuse of this drug is considered a particular risk with addicts to alcohol or other drugs. Symptoms of withdrawal from meprobamate have been likened to delirium tremens of alcohol withdrawal and can include tremors and twitches, trouble in controlling movement, insomnia, headache, vomiting, anxiety, confusion, and hallucinations. Convulsions are possible but uncommon. On rare occasion death has been attributed to withdrawal, but not all authorities agree that meprobamate is the sole cause. For sure, however, dogs that are dependent on the substance can go into convulsions and die if their supply is suddenly cut off.

Drug interactions. In mice nicotine reduces the time they are physically uncoordinated after a meprobamate dose, just as we might expect when a

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