P.J.A. Yeates & S.H.L. Thomas (Wolfson Unit of Clinical Pharmacology, University of Newcastle, UK)
Effectiveness of delayed activated charcoal administration in simulated paracetamol (acetaminophen) overdose.
Br.J.Clin Pharmacol, 49, 11-14.
Summary : Oral activated charcoal is used to treat drug overdose and is effective at reducing drug absorption when given within 1 hour of drug ingestion. In most cases of drug overdose, the delay in administering activated charcoal is more than 1 hour. This study has investigated the efficacy of activated charcoal at preventing paracetamol absorption after simulated overdose (3 gms. Paracetamol tablets in healthy volunteers) when administration was delayed between 1 and 4 hours. Dose of activated charcoal used was 50 gms. Plasma paracetamol concentrations were measured using HPLC.
Activated charcoal significantly reduced paracetamol AUC (4,9 hrs) when administered after 1 hr, but administration after 2 or 4 hrs did not have significant effect. Results in healthy volunteers cannot be directly extrapolated to patients of overdose, but they provide no evidence of efficacy for activated charcoal when administered after an interval of more than 2 hrs.
Henrik Toft Sorensen, Gunnar Lauge Nielsen, et al (Department of Internal Medicine V, Aarhus University Hospital Aarhus, Denmark)
Birth outcome following maternal use of metoclopramide
Br.J.Clin.Pharmacol, 49, 264-268.
Summary: Metoclopramide is an antiemetic drug used widely during pregnancy for nausea and vomiting. As its use is widespread, adverse effects on infants would have major public health implications.
This study has been conducted in Sweden, using the Pharmaco-Epidemiological Prescription Database. Three hundred and nine women who had prescriptions for metoclopramide from January to December 1996 were included in the study. Information on malformations, birth-weight, preterm deliveries and stillbirths were compared with controls (13,327 women) who did not receive prescriptions of any kind during pregnancy.
The authors could not document any association between the use of metoclopramide during pregnancy and adverse pregnancy outcome. As this is limited study, further research is required.
Jean Frederic Westphal (Unit of Geriatric Medicine, France)
Macrolide – induced clinically relevant drug interactions with cytochrome P-450a (cyp) 3A4: an update focused on clarithromycin, azithromycin and dirithromycin.
Br. Jr.Cl. Pharmacology, oct.2000, 50(4), 285-295
Summary: Erythromycin binds strongly, clarithromycin to a lesser extent and azithromycin the least to the cytochrome CYP 3A4, which is involved in oxidative phase of biotransformation of drugs. Hence, erythromycin produces maximum drug interactions and azithromycin and dirithromycin the least drug interactions.
Clinically relevant drug-interactions with benzodiazepines, neuroleptics, HMG CoA reductase inhibitors, anti-arrhythmic agents and warfarin are described.