What Is Cycloserine?

Cycloserine is an antibiotic that physicians may prescribe for the treatment of lung or systemic tuberculosis. Other uses of cycloserine include the treatment of certain urinary tract infections. As the drug is not typically as potent as conventional tuberculosis antibiotics, pharmacological studies suggest using the medication in conjunction with similar medications. Patients generally require routine blood tests to monitor the level of the drug in the bloodstream because of the potential risk of serious central nervous system side effects.

The antibiotic originates from the bacterial strain Streptomyces orchidaceus, discovered during the fermentation brewing process in the 1950s. Pharmaceutical companies either use the bacteria to produce cycloserine or manufacture the medication synthetically. The medication proved effective in fighting Mycobacterium tuberculosis, and researchers discovered that it also successfully treats infections caused by susceptible gram-negative and gram-positive bacteria, which includes the Enterobacter genus and Escherichia coli.

The drug helps to eliminate susceptible bacteria by preventing the organisms from producing a protective outer cellular membrane. Physicians usually require sputum or urine culture and sensitivity tests before prescribing cycloserine. The recommended cycloserine dose begins at 250 milligrams, which patients take in oral capsule form every 12 hours. Dosages must not exceed a total of 1 gram per day. Studies indicate taking the medication with a meal containing fatty foods reduces the drug's absorption by up to one half.

The kidneys eliminate the majority of the medication from the body, and pharmaceutical companies do not recommend the medication for patients with renal impairment. The drug may also reduce levels of vitamin B12 and folic acid in the body when taken with other anti-tubercular medications, and vitamin supplementation may be required. A combination of cycloserine and similar antibiotics may also affect red blood cell production by creating abnormally shaped and sized cells.

Side effects of cycloserine include dizziness, drowsiness, headaches, and joint pain, and some patients develop skin rashes. Patients should exercise caution and not operate motorized equipment or vehicles if experiencing alterations in cognition or consciousness. Patients taking more than 500-milligram per day may experience serious central nervous system reactions that include confusion, convulsions, or personality changes, in the form of aggressive or irritable behavior. These individuals might also suffer tremors or seizures.

Patients who experience serious reactions may require a dosage reduction or adjunctive treatment with antidepressant or anti-seizure medications. As the medication can produce a variety of central nervous system adverse effects, studies advise against prescribing the antibiotic for patients with epilepsy. Cycloserine interactions include alcoholic, as the combination can produce epileptic events. Taking the antibiotic with ethionamide or isozianid may increase the risk of serious neurological effects.