Azimilide

Tramadol-induced blockade of delayed rectifier potassium current in NG108-15 neuronal cells

Tramadol is a centrally acting analgesic drug used mainly in the moderate to severe pain control. In this study, the effects of this agent on ion currents of NG108-15 neuronal cells were investigated. This cell line expresses Kv3.1a mRNAs and exhibits the activity of delayed rectifier K(+) (K(DR)) channels. Tramadol suppressed the amplitude of delayed rectifier K(+) current (I(K(DR))) in a concentration-dependent manner with an IC(50) values of 25 microM. Tramadol (30 microM) also shifted the steady-state inactivation of I(K(DR)) to a more negative membrane potential by approximately -15 mV. The role of the K(DR) channel, particularly as a member of the Kv3 superfamily, is to stabilize the resting potential and to reduce the width of action potentials in the time-coding neurons. Tramadol-induced block of I(K(DR)) observed in this study could be partly responsible for its anti-depressant action.

Role of drug therapy for sustained ventricular tachyarrhythmias

Antiarrhythmic drug therapy, broadly defined, is the mainstay of treatment and prevention of ventricular tachycardia (VT)/ventricular fibrillation (VF), which can lead to sudden death. This article evaluates the evidence for and appropriate use of class I antiarrhythmic drugs, class III antiarrhythmic drugs, beta-blockers, nondihydropyridine calcium-channel blockers, statins, angiotensin enzyme inhibitors, angiotensin receptor blockers, aldosterone blockers, and digoxin for antiarrhythmic benefits in patients who have a propensity for VT/VF and therefore are at risk of sudden death.

Antiarrhythmic drugs: new agents and evolving concepts

Properties of several new antiarrhythmic drugs are summarised in this review article. Recent concepts concerning their safety and efficacy of antiarrhythmics are discussed. A brief perspective on possible future strategies for pharmacotherapy of arrhythmias is provided.

ADME evaluation. 2. A computer model for the prediction of intestinal absorption in humans

PURPOSE

To develop a computational method to rapidly evaluate human intestinal absorption, one of the drug properties included in the term ADME (Absorption, Distribution, Metabolism, Excretion). Poor ADME properties are the most important reason for drug failure in clinical development.

METHODS

The model developed is based on a modified contribution group method in which the basic parameters are structural descriptors identified by the CASE program, together with the number of hydrogen bond donors.

RESULTS

The human intestinal absorption model is a quantitative structure-activity relationship (QSAR) that includes 37 structural descriptors derived from the chemical structures of a data set containing 417 drugs. The model was able to predict the percentage of drug absorbed from the gastrointestinal tract with an r2 of 0.79 and a standard deviation of 12.32% of the compounds from the training set. The standard deviation for an external test set (50 drugs) was 12.34%.

CONCLUSIONS

The availability of reliable and fast models like the one we propose here to predict ADME/Tox properties could help speed up the process of finding compounds with improved properties, ultimately making the entire drug discovery process shorter and more cost efficient.