Thalidomide is a drug that was marketed in the late 1950s and early 1960s in Great Britain and Europe. It was used both as a sleeping pill and as an antidote to morning sickness in pregnant women.
In 1962, a host of usually rare limb abnormalities suddenly became much more common. About 10,000 babies were born displaying, in particular, a shortening of the arms and/or legs called phocomelia. In phocomelia, for example, the baby may be born with the upper arm and forearm completely absent, and the hand attached to the trunk of the body by a short little bone. This same situation can occur with the legs, so that the majority of the leg is totally absent, and the foot is attached to the trunk of the body. Other babies were born with amelia, the complete absence of one or more limbs. Other birth defects involving the eyes, teeth, heart, intestine, and anus were similarly noted to be significantly more common.
These birth defects were soon traced to the drug thalidomide, which was proven to be a potent teratogen (substance which interferes with normal development in the embryo). In fact, studies showed that fully 20% of all babies exposed to thalidomide during their first eight weeks in the uterus were born with the characteristic abnormalities described above. Because the skeletal system begins to be formed as early as the third week of development, and small buds which will become the limbs appear around week five, anything which interferes with development at this very early stage has devastating effects. Once the marketing of thalidomide was halted, these birth defects again became rare occurrences.
Currently, thalidomide has been shown to have some use in the treatment of two different illnesses. In leprosy, also known as Hansen's disease, a bacterial disease causing both skin and nervous system problems, thalidomide has some effect against inflammation and pain. The FDA approved thalidomide for use in certain forms of leprosy, with very strict safeguards in place against use of the drug in pregnant women. A special program, called System for Thalidomide Education and Prescribing Safety (STEPS) approves only specified practitioners to prescribe thalidomide. Mandatory monthly pregnancy tests for all women of childbearing age taking the drug, as well as a requirement that two reliable forms of birth control be used by such women who are given thalidomide, are part of the STEPS program. Men are required to sign a statement that they will use a latex condom during all sexual encounters, even if they have previously undergone a vasectomy. Required video education, strict patient registeries, small prescription amounts (thalidomide is only to be prescribed for one month at a time), and careful monitoring are also part of the STEPS program. Studies are also underway to explore using thalidomide to help guard against immune system rejection of bone marrow transplants, ulcers and severe weight loss in AIDS, systemic lupus erythematosus, breast cancer, and Kaposi's sarcoma, multiple myeloma, kidney cancer, brain tumors, and prostate cancer.
See also Embryo and embryonic development.
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