A new chemical method to measure the alkaloid ibogaine in biological samples uses extraction, derivatization, and gas chromatography-mass spectrometry, with a deuterated internal standard. Standard curves for ibogaine (50-400 ng) were linear. The detection limit is about 20 ng/mL of tissue extract (180 ng/g tissue), with a coefficient of variation of 8 to 12.5%. Aqueous ibogaine solutions (1-10 mg/mL) stored at 10°C for up to 7 months showed no more than 10% loss. Measuring brain ibogaine in rats 1 and 19 hours after a 40 mg/kg dose suggests rapid drug disappearance. The method will help reveal ibogaine's pharmacokinetic properties.
Ibogaine pretreatment in rats did not alter brain morphine levels at 30 minutes or 2 hours after injection, but it significantly increased brain amphetamine levels at both time points, with a greater increase at 2 hours. These findings suggest that ibogaine irreversibly inhibits an enzyme that metabolizes amphetamine, indicating that the functional interactions between ibogaine and amphetamine, unlike those with morphine, may stem from a drug-drug interaction in the liver.