Stopping warfarin for dental procedures
QHow safe is it to stop warfarin before dental treatment?
AEvidence is limited. In theory, risks and benefits vary according to the indication for anticoagulation and nature of the procedure.
For patients awaiting elective procedures and taking warfarin for a limited time (for six months following a DVT, for example), the procedure should be postponed until warfarin has been stopped.
For patients on long-term warfarin for atrial fibrillation, mechanical heart valves or recurrent venous thromboembolism, UK Medicines Information (UKMI) says warfarin does not need to be stopped before primary care dental surgical procedures. Although continuing the warfarin exposes the patient to an increased risk of bleeding, the risk seems minimal.
Nevertheless, an INR should be measured within 24 hours of the procedure and UKMI recommends that no individual with an INR >4.0 should have a dental procedure in primary care.
If after consultation with the anticoagulant clinic the warfarin dose and INR can be reduced, the procedure could be deferred. However, for patients with mechanical prosthetic heart valves, for example, whose target INR may be close to 4.0, management in a dental hospital is preferred. They are also at risk of endocarditis, and antibiotic prophylaxis should be given.
UKMI also recommends that warfarin patients with hepatic or renal disease or those on cytotoxics or chemotherapy should have dental procedures in hospital. Advice on haemostasis after the procedure is available at the UKMI website.
Dr Chris Skene, research registrar, Wolfson Institute for Biomedical Research, London
Use of ezetimibe in lowering cholesterol
QWhat is the place of ezetimibe in lipid regulation? By how much will it reduce cholesterol?
AEzetimibe is the first of a new class of anti-hyperlipidaemic agents, the cholesterol absorption inhibitors. It is indicated for monotherapy or with statins in patients with hypercholesterolaemia and is used with statins in patients with homozygous familial hypercholesterolaemia.
In a recent review, oral ezetimibe 10mg once daily reduced intestinal cholesterol absorption by 54 per cent; this was associated with a rise in endogenous cholesterol synthesis. Within two weeks, ezetimibe monotherapy produced a 17-20 per cent reduction in low-density lipoprotein (LDL) cholesterol. With statins, ezetimibe produced a reduction in LDL cholesterol of up to 40 per cent.
Ezetimibe appears well tolerated with a safety profile similar to that of placebo and is subject to minimal drug interactions.
Ezetimibe is an option for monotherapy in patients with mild hypercholesterolaemia or as an adjuvant. It may be useful in patients at risk of adverse events from other anti-hyperlipidaemic agents, and may allow lower doses of statins.
Because trials have lasted no longer than 12 weeks the long-term effects on cardiovascular morbidity and mortality remain to be determined. Given the long experience with statins and the evidence that they reduce cardiovascular events in at-risk patients, the consensus view is that statins should be used first-line for cholesterol lowering, with ezetimibe being added if the degree of cholesterol reduction is suboptimal, or substituted if the statin gives adverse effects.
Dr Albert Ferro, senior lecturer in clinical pharmacology,
King's College London