Bioavailability of diclofenac potassium at low doses.

Aim: Diclofenac-K has been recently launched at low oral doses in different countries for over-the-counter use. However, given the considerable first-pass metabolism of diclofenac, the degree of absorption of diclofenac-K at low doses remained to be determined. The aim of this study was to determine the bioavailability of low-dose diclofenac-K.

Effect of amiodarone on the plasma levels of metoprolol.

On average, metoprolol plasma concentration is doubled after an amiodarone loading dose (1.2 g/day over a period of 6 days). However, the individual amount of this drug interaction depends on the CYP2D6 genotype.

Carvedilol but not metoprolol reduces beta-adrenergic responsiveness after complete elimination from plasma in vivo.

Background: Carvedilol but not metoprolol exhibits persistent binding to beta-adrenergic receptors (beta-ARs) even after washout in cell culture experiments. Here, we determined the significance of this phenomenon on human beta-ARs in vitro and in vivo.

Methods And Results: Experiments were conducted on human atrial trabeculae (n=8 to 10 per group).

CYP2D6 genotype: impact on adverse effects and nonresponse during treatment with antidepressants-a pilot study.

Objective: Treatment with antidepressants is frequently associated with adverse effects or insufficient clinical response. Several antidepressants are metabolized by cytochrome P450 (CYP) 2D6. The activity of this enzyme markedly varies among individuals from poor to ultrarapid metabolism on the basis of the polymorphism of the CYP2D6 gene.

Increased frequency of cytochrome P450 2D6 poor metabolizers among patients with metoprolol-associated adverse effects.

Objective: The CYP2D6 genotype is a major determinant of interindividual differences in metoprolol plasma clearance. Cytochrome P450 2D6 (CYP2D6) poor metabolizers exhibit 3- to 10-fold higher plasma concentrations after administration of metoprolol than extensive metabolizers. However, the impact of the CYP2D6 genotype on the occurrence of adverse effects of metoprolol remains controversial.

Effect of the CYP2D6 genotype on metoprolol metabolism persists during long-term treatment.

The beta1 selective beta-blocker metoprolol is metabolized predominantly but not exclusively by CYP2D6. Due to the polymorphism of the CYP2D6 gene, CYP2D6 activity varies markedly between individuals. Consequently, after short-term administration metoprolol plasma concentrations were found to be several fold higher in poor metabolizers than in extensive metabolizers.