It is apparent that MTX is a useful agent in the treatment of rheumatoid arthritis resistant to first and second line therapies. However, despite its long term use in this disease, considerable uncertainty exists about the basic pharmacokinetics of low dose oral MTX and therefore about its pharmacodynamics. It is probable that when MTX is re-examined with the help of modern analytical technology in a rheumatoid setting that pharmacological insights to the variability in dose-response relationships for efficacy and certain toxicities may emerge. There is still considerable uncertainty of the hepatotoxic potential of MTX. Further investigation of the accumulation of active polyglutamated MTX in liver may throw light on the likelihood of promoting iatrogen disease and perhaps the contribution of oral administration to this problem. Finally, examination of dose-response relationship utilising accurate pharmacokinetics may help to establish guidelines for the safe and effective usage of MTX in rheumatoid arthritis.

Administration, Oral↗

PubMed1987

Common prescribing errors.

Explore the source record for details and available documents.

Drug Interactions↗

PubMedDate not supplied

Management of dapsone poisoning complicated by methaemoglobinaemia.

The currently recommended dosage regimen for methylene blue (intermittent bolus dose) in the treatment of methaemoglobinaemia caused by dapsone is often inadequate. This is due to the long half-life of dapsone which provides a continuing oxidative stress that can cause a recurrence of clinically significant methaemoglobinaemia. Methylene blue infusion is effective, as demonstrated in an illustrative case report, and should be supported by repeated doses of activated charcoal to enhance dapsone elimination. The principles of treatment of methaemoglobinaemia due to dapsone can be applied to methaemoglobinaemia due to any agent producing prolonged oxidative stress.

Adult↗

PubMedDate not supplied

The assessment and treatment of theophylline poisoning.

Theophylline poisoning long has been recognized as difficult to treat and still has an over-all mortality rate of about 10%. In recent years, the increasing use of sustained-release preparations has changed the pattern of toxicity. The management of theophylline toxicity is compounded by clinical differences between chronic (overmedication) intoxication and acute single ingestions of a large amount of the drug, inter- and intraindividual variability in theophylline metabolism and dose-dependent kinetics in poisoned patients. Management decisions should be based on both clinical assessment and laboratory information (particularly theophylline concentrations).

Charcoal↗