Following intramuscular injection of 1 g of streptomycin as the sulfate, a peak serum level of 25 to 50 mcg/mL is reached within 1 hour, diminishing slowly to about 50 percent after 5 to 6 hours.

Appreciable concentrations are found in all organ tissues except the brain. Significant amounts have been found in pleural fluid and tuberculous cavities. Streptomycin passes through the placenta with serum levels in the cord blood similar to maternal levels. Small amounts are excreted in milk, saliva, and sweat.

Streptomycin is excreted by glomerular filtration. In patients with normal kidney function, between 29% and 89% of a single 600 mg dose is excreted in the urine within 24 hours. Any reduction of glomerular function results in decreased excretion of the drug and concurrent rise in serum and tissue levels.^[1]

Adapted from the FDA Package Insert.