Centrifugation as a countermeasure during bed rest and dry immersion: What has been learned?

OBJECTIVES: We review the studies that have evaluated intermittent short-radius centrifugation as a potential countermeasure for cardiovascular, musculoskeletal, and sensorimotor deconditioning in simulated weightlessness. METHODS: The findings from 18 experimental protocols that have used bed rest and dry immersion for comparing the protective effects of centrifugation versus standing upright or walking, and the effects of continuous vs. periodic exposure to centrifugation are discussed. RESULTS: Centrifugation for as little as 30 min per day was found to be effective in mitigating orthostatic intolerance and strength in postural muscle after 5 days of bed rest, but it was not effective in mitigating plasma volume loss. CONCLUSION: To determine the optimal prescription for centrifugation as a countermeasure, we recommend further studies using (a) bed rest of longer duration, (b) individualized prescriptions of centrifugation combined with exercise, and

Effects of five days of bed rest with intermittent centrifugation on neurovestibular function.

OBJECTIVES: We tested whether intermittent short-radius centrifugation was effective for mitigating alteration in balance and gait following bed rest. METHODS: Ten male subjects were exposed to 5 days of 6° head-down tilt bed rest with: (a) no countermeasure; (b) daily 1-g centrifugation for a continuous 30-min period; and (c) daily 1-g centrifugation for six periods of 5 min. During and after the bed rest, subjects were asked to scale the severity of neurovestibular symptoms that followed centrifugation or 80° head-up tilt. Following the bed rest, equilibrium scores were derived from anterior-posterior sway while standing on a foam pad with the eyes open or closed while making pitch head movements, and gait was evaluated by grading subjects' performance during various locomotion tasks. RESULTS: At the beginning of bed rest, one single 30-min period of centrifugation induced more severe neurovestibular symptoms than six periods of 5-min centrifugation. After bed rest, although equilibrium scores and gait performance were not significantly altered, subjects felt less neurovestibular dysfunction with orthostatic stress when centrifugation was used. CONCLUSION: Centrifugation was effective at reducing the severity of neurovestibular symptoms after bed rest, but this decrease was not different between one or multiple daily sessions.

Dual-release formulation, a novel principle in L-dopa treatment of Parkinson's disease.

A single morning dose of dual-release formulation was compared with a slow-release formulation of L-dopa plus benserazide in a randomized, double-blind, cross-over study in 16 fluctuating patients with PD. The mean time to "on" was shorter with the dual-release formulation (43 +/- 31 minutes) than with the slow-release formulation (81 +/- 39 minutes) (p < 0.001), whereas the mean time to relapse to "off" was similar for both formulations. The dual-release formulation had a significantly shorter time to reach peak concentration (t(max)) and greater maximum concentration (C(max)) and area under the plasma concentration time curve (AUC(0--5 h)) than the slow-release formulation, whereas apparent elimination half-life (t(1/2)) was similar for both formulations.

[Liver damage and nonsteroidal anti-inflammatory drugs: case non-case study in the French Pharmacovigilance Database]. / Atteintes hépatiques et médicaments anti-inflammatoires non stéroïdiens: étude cas/non cas dans la Banque Nationale de Pharmacovigilance.

This study investigates the relationship between exposure to non-steroidal anti-inflammatory drugs (NSAIDs) and liver injuries using the French Pharmacovigilance Database. We use the case/non-case methodology, where 'cases' were reports of the reactions of interest (liver injuries as recorded in the database according to the WHO-ART classification including cytolytic and cholestatic hepatitis, acute hepatitis, liver enzyme elevations). 'Non-cases' were all reports of reactions other than these being studied. Amineptine and acetaminophen were used as 'positive controls'. Among the 42,913 adverse drug reactions recorded in the database between January 1995 and December 1997, 5708 (13 per cent) were liver injuries. In comparison with other drugs in the database, liver injuries were inversely associated with exposure to NSAIDs, whatever the class of the drugs (OR 0.3 [0.3-0.4]). In contrast, liver injuries were significantly related to acetaminophen (OR 2.1 [1.9-2.3]), and amineptine (OR 14.0 [10.5-18.7]). Naproxen and diclofenac were associated with a higher frequency of liver injuries, respectively 15.7 per cent and 11.5 per cent. The risk associated with NSAIDs alone significantly decreased when the analysis was performed after exclusion of hepatotoxic drugs associated with NSAIDs (except for naproxen). The present results show the low frequency of liver damage associated with NSAIDs. The main factor appears to be concomitant exposure to other hepatotoxic drugs.

[Drug interactions: a prospective pilot study in primary health care]. / Interactions médicamenteuses: à propos d'une étude prospective pilote en médecine générale libérale.

The present prospective pilot study investigated putative drug interactions in primary health care. Among 110 outpatients, 50 were treated with more than one drug (maximum = 10). Among these 50 prescription forms, 21 concerned at least one drug interaction, with a total of 47 different drug interactions. Most of them (94 per cent) were explained by a pharmacodynamic mechanism. They were classified as 'requiring use precautions' (64 per cent), 'to be taken into account' (25 per cent) or 'inadvisable' (11 per cent). None of them was 'contraindicated'. Most often the drugs involved were diuretics, converting enzyme inhibitors or non-steroidal antiinflammatory drugs. Drug interactions, which concern around one in five prescription forms, remain an important topic in Clinical Pharmacology.