The Role of the Cycloserine (Seromycin) Blood Level in the Treatment of Pulmonary Tuberculosis and the Prevention and Control of Cycloserine (Seromycin) Toxicity

¹ Pittsburgh State Tuberculosis Hospital, Division of Tuberculosis Control, Pennsylvania Department of Public Health.

Cycloserine alone was administered during the first three months of a study of 60 treatment failure cases of pulmonary tuberculosis. For the remaining six months of the study, cycloserine was combined with isoniazid.

The Jones Modification of the colorimetric determination of cycloserine in the serum was employed in determining cycloserine blood levels. The control and effective treatment levels ranged between 20 and 40 micrograms of cycloserine per mililiter of blood.

Six per cent of the cases studied showed neurotoxicity. However, these toxic effects were reversible without sequelae when cycloserine was discontinued.

There was sputum conversion in 25 per cent and regression of x-ray lesions in 42 per cent of the cases studied.

It was concluded that with cycloserine blood level determinations, cycloserine toxicity can be prevented or controlled; and that cycloserine is an effective antimicrobial drug, best used in combination with isoniazid.