Amiodarone: electrophysiologic actions, pharmacokinetics and clinical effects

Interest in amiodarone has increased because of its remarkable efficacy as an antiarrhythmic agent. The purpose of this report is to review what is known about the electrophysiologic actions, hemodynamic effects, pharmacokinetics, alterations of thyroid function, response to treatment of supraventricular and ventricular tachyarrhythmias and adverse effects of amiodarone. Understanding the actions of amiodarone and its metabolism will provide more intelligent use of the drug and minimize the development of side effects. The mechanism by which amiodarone suppresses cardiac arrhythmias is not known and may relate to prolongation of refractoriness in all cardiac tissues, suppression of automaticity in some fibers, minimal slowing of conduction in fast channel-dependent tissue, or to interactions with the autonomic nervous system, alterations in thyroid metabolism or other factors. Amiodarone exerts definite but fairly minor negative inotropic effects that may be offset by its vasodilator actions. Amiodarone has a reduced clearance rate, large volume of distribution, low bioavailability and a long half-life that may last 2 months in patients receiving short-term therapy. Therapeutic serum concentrations range between 1.0 and 3.5 micrograms/ml. The drug suppresses recurrences of cardiac tachyarrhythmias in a high percent of patients, in the range of 80% or more for most supraventricular tachycardias and in about 66% of patients with ventricular tachyarrhythmias, sometimes requiring addition of a second antiarrhythmic agent. Side effects, particularly when high doses are used, may limit amiodarone's usefulness and include skin, corneal, thyroid, pulmonary, neurologic, gastrointestinal and hepatic dysfunction. Aggravation of cardiac arrhythmias occurs but serious arrhythmias are caused in less than 5% of patients. Amiodarone affects the metabolism of many other drugs and care must be used to reduce doses of agents combined with amiodarone.     

Liraglutide: from clinical trials to clinical practice

Liraglutide, a once-daily glucagon-like peptide-1 receptor agonist, is approved for use as monotherapy in the USA and Japan (but not in Europe or Canada) and in combination with selected oral agents (all regions) for the treatment of patients with type 2 diabetes. Guidance from local advisory bodies is emerging on the most appropriate place for liraglutide in the treatment pathway. It is apparent from its phase 3 clinical trial programme that liraglutide provides superior glycaemic control compared with that achieved with other antidiabetic agents used early in the treatment pathway (e.g. glimepiride and sitagliptin). Key additional benefits include a low incidence of hypoglycaemia and clinically relevant weight loss, although these benefits may be ameliorated by concomitant sulphonylurea (SU) treatment and, in the case of hypoglycaemia, reduction of the SU dose may be necessary. Overall, the profile of liraglutide is similar and, in some aspects, superior to twice-daily exenatide. The implementation of liraglutide therapy is straightforward, with simple dose titration from the starting dose of 0.6 to 1.2 mg/day after 1 week; some patients may benefit from additional titration to 1.8 mg/day. Treatment is self-administered by subcutaneous injection. This contrasts with other agents used early in the treatment pathway, but clinical data suggest patients' overall treatment satisfaction with liraglutide is similar (1.2 mg) or better (1.8 mg) than that with sitagliptin despite differing administration methods. Some patients may experience nausea when initiating liraglutide treatment, but the titration regimen is designed to improve tolerability and clinical data indicate nausea is transient.     

Angiogenesis antagonists: current clinical trials

The Third Annual Cambridge Healthtech Institute symposium, entitled Angiogenesis Antagonists: Current Clinical Trials, Drug Development and Regulatory Issues, co-sponsored by the journal Angiogenesis and the Angiogenesis Foundation, convened on October 19 and 20 in Bermuda. The meeting attracted international experts from academia, the biopharmaceutical industry and the National Cancer Institute to share initial experiences in clinical trials of therapeutic modulation of angiogenesis. As molecular inhibitors move rapidly from the laboratory to the clinic, practical strategies were advanced to accelerate the introduction of the emerging class of pharmacological agents—angiogenesis antagonists. Themes of the meeting included:(1) An update of current clinical trials.(2) Specific disease/organ sites selected for anti-angiogenesis therapy.(3) Potential and actual toxicities.(4) The use of drug synergisms, combining angiogenesis antagonists with cytotoxic therapy.(5) Mechanisms for funding.(6) Overcoming regulatory hurdles to introduce new compounds.     

Intra-articular steroids: Confounder of clinical trials

Summary The effect of intra-articular (i-a) steroid injection on ESR and C-reactive protein (CRP) in rheumatoid arthritis (RA) was investigated. One week following injection of 1 or 2 knees there was a significant fall in ESR (p<0.0001) and CRP (p<0.01) in a cohort of 20 RA patients. The mean drop for both ESR and CRP was 46%. This effect lasted over a variable period up to 6 months. A survey of 50 published drug efficacy studies in RA revealed that, while 44 used ESR and 20 CRP as efficacy measures, 37 neither excluded nor recorded i-a steroid injections during the study. Steroid injections were excluded in 8 studies and recorded in 5, being used as an outcome measure in 2 of these. It is recommended that the frequency with which i-a injections are used in drug efficacy studies is reported and that they are avoided in the 3 months preceding an outcome measurement if ESR or CRP are being used as outcome measures.     

Monitoring clinical trials: a practical guide

This article describes the processes and procedures involved in planning, conducting and reporting monitoring activities for large Clinical Trials of Investigational Medicinal Products (CTIMPs), focusing on those conducted in resource‐limited settings.