Platelets are the blood clotting elements of the blood that prevent the body from bleeding out for excessively long periods after an injury. Platelets also bandage small tears in the inside layers of blood vessels. Normal platelet levels are between 150,000 and 400,000 per microliter. Low platelet count, known as thrombocytopenia, can be a side effect of certain medications.
Heparin is a medication used medically and purposely to keep the blood thin, preventing and treating clots. Its action is desired in the treatment of people with deep vein thrombosis and those at high risk for cardiovascular events, pulmonary embolism and heart attacks. The drug works by inhibiting certain required factors along the clotting pathway. A side effect for physicians and patients to be wary of is thrombocytopenia, according to Drugs.com.
The Mayo Clinic Online Library lists the use of quinine medications as able to induce a thrombocytopenic reaction. This reaction may cause autoimmune destruction of the cells. The body's immune system will confuse platelets for something foreign to the body and wage an attack against them. A 2004 "Archives of Internal Medicine" article notes that other drugs cause this reaction as well, but that Quinine is the oldest recognized amongst them. The severity of the thrombocytopenic reaction caused by Quinine resulted in the FDA banning its availability over-the-counter in 1994 and highly recommending that it not be used as a prescription. Quinine is no longer used to treat malaria in the U.S., according to this article but remains an effective preventive treatment for nocturnal leg cramps, restless leg syndrome and some arrhythmias.
The phrase sulfa drugs is an umbrella term that includes very different drugs, grouped together based on the fact that they all contain a particular sulfur-based molecule, SO2NH2. According to the 2010 LiveStrong.com article "Drug List for Sulfa Allergy," these medications include the antibiotic class known as sulfonamides, diuretic pills from the Loop and Carbonic Anhydrase Inhibitor class, diabetic medications known as sulfonylureas and the strongest of all non-steroidal anti-inflammatory drugs, Celebrex. The Lab Tests Online resource notes that sulfa drugs are a common cause of medication-induced thrombocytopenia.
Anticonvulsant medications, also known as anti-epileptics are drugs used to treat seizures and sometimes, nerve pain disorders. Anticonvulsants as a broad category, were listed by Mayo Clinic as able to induce thrombocytopenia. A journal article published in the January-February 2006 issue of "Psychosomatics," takes a look at the thrombocytopenic results of the anticonvulsant drug, Oxcarbazepine. The authors note that although the label does not specifically list thrombocytopenia as a side effect of Oxcarbazepine use in adults and only the possibility of it in children, case-reports have provided speculation into their cause and effect relationship. The authors note that physicians prescribing anticonvulsants should be aware of this potential and advise proper screening and long-term monitoring while on the drug.