Abstract
1. Intravenous injection of cocaine in the dog is followed by a rapid initial drop in the plasma concentration. The subsequent gradual decrease in plasma level is probably due to tissue metabolism and to a small extent, urinary excretion.
After subcutaneous injection the peak plasma levels are lower but sustained for a much longer period than after intravenous injection.
Oral administration (via stomach tube) gives plasma concentrations which are low and of short duration.
2. About 1 to 12 per cent of the administered cocaine is excreted over a 24 hour period in the urine of the dog. Accordingly 88 to 99 per cent of the cocaine is metabolized by this species.
3. After subcutaneous injection of comparable doses the rabbit shows a much lower plasma level of cocaine than the dog.
4. Traces (less than one per cent of injected dose) of cocaine may be found in rabbit urine collected by catheter drainage. However, no cocaine can be found in rabbit urine collected in the cage.
5. Thirty minutes after the intravenous injection of 20 mgm./kgm. of cocaine the concentrations of cocaine in the spleen and kidney were higher than in any other tissue, being about three times that of the liver but only 30 per cent higher than cerebral cortex. Cocaine has a much greater affinity for tissues than for plasma.
6. The convulsive plasma level of cocaine in the intact dog was from 3.3 to 6.9 microgm. per ml. and in the curarized dog prepared for EEG recording was 9.5 to 10 microgm. per ml.
Footnotes
- Received October 30, 1950.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|