Modulation of ethanol-induced central nervous system depression by ibuprofen

Antagonism of ethanol by pretreatment or posttreatment with RO 15-4513 and indomethacin alone or in combination

RO 15-4513, an inverse agonist at the GABA/benzodiazepine receptor Cl- channel complex, antagonizes multiple effects of ethanol. Prostaglandin synthesis inhibitors, such as indomethacin, also antagonize several effects of alcohols. However, prostaglandin synthesis inhibitors and RO 15-4513 each provide only partial antagonism of ethanol, typically seen as a dose-related effect with a maximum efficacy of approximately 50%. The purpose of this study was to: (1) compare the relative efficacy of these compounds for antagonizing ethanol; (2) compare the effectiveness of preethanol treatment versus postethanol treatment with each drug; and (3) compare the effect of RO 15-4513 and indomethacin in combination with the effects of each drug alone. The results show that indomethacin significantly decreased duration of loss of the righting reflex when administered either pre- or postethanol. Conversely, RO 15-4513 decreased duration of loss of the righting reflex only when given preethanol. When coadministered, RO 15-4513 and indomethacin did not show additive or synergistic effects. Compounds from these two drugs classes should continue to prove useful in elucidating ethanol's mechanisms of action.

Indomethacin and cognitive function in healthy elderly volunteers

1. Cognitive function was studied after single and multiple doses of indomethacin (I) and matched placebo (P) in 20 healthy elderly volunteers using a double-blind crossover design. 2. Arousal, attention, integration, coordination, memory and mood were investigated using a battery of psychomotor tests and the Hospital Anxiety and Depression Scale. Assessments were performed before and after the first and last doses of a 7 day course of medication. 3. Critical flicker fusion threshold fell by a mean of 1.96% on indomethacin compared with a 1.13% rise on placebo 5 h after the first dose (P = 0.029). A beneficial effect on choice reaction time latency (P = 0.012) was seen both after acute and continuing administration of indomethacin. Performance at the most discriminating level (level 3) of the paired word association test was significantly better following 8 days of treatment with indomethacin in the younger (55-65 year-old) age group (P = 0.001). 4. There was no significant difference in performance on the symbol-digit substitution test and the continuous attention task. No change was seen in hospital anxiety and depression scale scores. 5. These results suggest that performance on tests of sensorimotor coordination and short term memory may improve in healthy volunteers following indomethacin administration, whereas tests of attention and psychomotor speed remain unaffected. However, further controlled studies in rheumatic patients are needed to evaluate fully the psychomotor effects of indomethacin and other NSAIDs in clinical practice.

Where are peripheral analgesics acting?

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Acetaminophen fails to inhibit ethanol-induced subjective effects in human volunteers

In animals, ethanol causes some of its CNS effects by releasing prostaglandins (PG); this is demonstrated by reports that prostaglandin synthetase inhibitors (PGSIs) diminish ethanol-induced effects. However, use of animals in these studies has precluded testing for subjective effects. We studied the interaction of ethanol and acetaminophen, a PGSI, in a double-blind crossover experiment. Six adult males were given no drug or acetaminophen (0, 325, 650, 1300 or 1950 mg) 75 min before ethanol (total dose = 0.625 g/kg; five divided doses). Physiologic, subjective and performance measures were collected. Compared to the no drug condition, ethanol significantly increased ratings of drug "liking," "drunk," "sluggish" and "drug strength" and decreased ratings of "sober." Ethanol increased heart rate and acetaminophen did not diminish or enhance this effect. The failure to antagonize ethanol-induced subjective and physiologic effects by acetaminophen in humans may be due to species differences or inadequate dosage of the PGSI. It is also possible that subjective and certain physiologic effects of ethanol in humans are not mediated by prostaglandin-dependent neural processes. Nevertheless, the finding that at greater than typical analgesic doses, acetaminophen failed to prevent subjective effects of ethanol is of clinical significance.

Cyclooxygenase inhibitors antagonize the rate-depressant effects of ethanol on fixed-ratio responding

Prostaglandin synthetase inhibitors (PGSIs), which inhibit actions of the enzyme complex cyclooxygenase, significantly antagonize the effects of alcohols but not other sedative-hypnotics across a broad range of measures. This suggests that certain actions of alcohols, in particular ethanol, are mediated at least partially through a prostaglandin-related pathway. This study examined changes in the rate-depressant effects of ethanol in an operant task following pretreatment with either of two PGSIs, indomethacin (INDO) or aspirin (ASP). Water reinforcement maintained the responding of male Sprague-Dawley (SD) rats under a Fixed-Ratio (FR) 32 schedule. Saline, INDO or ASP had no significant effect on control rates of responding. INDO pretreatment significantly antagonized the rate-depressant effects of 1.0 and 1.5 g/kg ethanol. ASP pretreatment also resulted in significant antagonism of ethanol's rate-decreasing effects. INDO was more potent than ASP in antagonizing the rate-depressant effects of ethanol. These results provide further support for the hypothesis that alcohols, by fluidizing neuronal membranes and mobilizing the release of arachidonate, serve to increase prostaglandin production, resulting in some of the behavioral and physiological sequellae of ethanol administration.

Prostaglandins in cerebrospinal fluid of healthy human volunteers, abstinent alcoholics and rhesus monkeys

A sensitive and selective assay for measuring prostaglandins in cerebrospinal fluid has been developed, based on the selected-ion-monitoring, electron-capture negative ionization GC/MS detection for the MO-PFB-TMS derivatives of prostaglandins E2, E1, F2 alpha, F1 alpha, and 6-keto-F1 alpha. Improvements over previously published assay procedures have been made, and the new assay has been applied to measurement of prostaglandin concentrations in lumbar CSF of healthy human volunteers, abstinent alcoholic patients, in cisternal CSF of Rhesus monkeys, and continuously sampled lumbar CSF of awake Rhesus monkeys. Results indicated that the concentrations of PGE2, PGE1, PGF1 alpha, and 6-keto-PGF1 alpha were below 15 pg/mL CSF in lumbar CSF of healthy humans and abstinent alcoholics, and in cisternal CSF of Rhesus monkeys. In contrast, continuously sampled lumbar CSF of awake Rhesus monkeys contained more than 200 pg/mL of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha, probably present as a result of local production.

Essential fatty acid supplementation during early alcohol abstinence

Interactions between ethanol, prostaglandins, and essential fatty acids (EFA) have led to the hypothesis that acute alcohol withdrawal and the sequelae of chronic alcoholism may be related to an EFA/prostaglandin deficiency. To test this hypothesis, EFA profiles in blood-lipid fractions, serum liver enzymes, cognitive function, and alcohol craving were measured in 27 acutely abstinent alcoholics before and after a 3-week double-blind trial of EFA supplementation. Upon entry into the study, alcoholics had significant differences in EFA levels as compared to normal controls, and serum levels of liver enzymes tended to correlate with these EFA levels. After 21 days, cognitive function, alcohol craving, and liver enzymes all improved in both the EFA and placebo groups; most EFA levels also approached normal values. There were no treatment effects of EFA supplementation at the dose used.