Ibogaine is currently being investigated for its potential use as an anti-addictive agent. In the present study we sought to determine whether prior morphine exposure influences the ability of ibogaine to inhibit morphine-induced locomotor stimulation. Female Sprague-Dawley rats were pretreated once a day for 1-4 days with morphine (5, 10, 20 or 30 mg/kg, i.p.) or saline and then received ibogaine (40 mg/kg, i.p.) 5 h after the last morphine pretreatment dose. Compared to rats pretreated with saline, rats pretreated with morphine (10, 20 or 30 mg/kg, i.p.) before ibogaine (40 mg/kg, i.p.) showed a significant reduction in morphine-induced (5 mg/kg, i.p.) locomotor stimulation when tested 29 h after ibogaine administration. Furthermore, this effect was apparent over a range of ibogaine (5-60 mg/kg, i.p.) and morphine test (2.5-5 mg/kg, i.p.) dosages. Doses of ibogaine (5 and 10 mg/kg, i.p.) which alone were inactive inhibited morphine-induced locomotor activity when rats had been pretreated with morphine. These results, showing that morphine pre-exposure affects ibogaine activity, suggest that variable histories of opioid exposure might account for individual differences in the efficacy of ibogaine to inhibit opioid addiction.

No abstract

Based on an empirical dosimetry model, estimates have been calculated and are presented on the mean active bone marrow dose to adults from diagnostic radiography, fluoroscopy, and dental radiography, as practiced in the United States in 1970. The annual per capita mean active bone marrow dose to adults in 1970 from the above practices is estimated to have been 103 mrad: 77, 20 and 3% from radiographic, fluoroscopic and dental examinations respectively. The per capita mean active bone marrow dose for various age groups is discussed. Contributions to the dose within a given age group from different examinations indicate that in the IS-34-yr age group, lumbar and lumbosacral spine examinations contribute most to the mean active bone marrow dose; thereafter, upper GI series and barium enemas are the highest contributors. Mean active bone marrow doses for children have not been estimated because of insufficient data. However, the lower rate of use of diagnostic X-rays (except dental) in children would reduce the annual per capita mean active bone marrow dose for the entire population to a maximum of approximately 77mrad. In 1%4 the annual per capita mean active bone marrow dose to adults is estimated to have been 83mrad. It is hypothesized that the increase in adult dose in 1970 was a result of a greater use of grids and grids having a higher ratio in 1970 as compared with 1%4. A comparison of the results with surveys of radiation doses from diagnostic radiology performed in other countries and with natural radiation background is described.

No abstract