Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mexiletine is a Class IB antiarrhythmic which has basic and clinical electrophysiologic properties similar to lidocaine. Like other Class I antiarrhythmic agents, mexiletine blocks the rapid inward sodium current responsible for phase 0 of the action potential. It has been noted in the clinical electrophysiology laboratory to have minimal effect on sinus node function and AV nodal and His-Purkinje system conduction. Pharmacokinetic studies have shown that oral absorption is rapid with bioavailability of 80-90%. Mexiletine is predominantly metabolized by the liver with elimination half-life of 9 to 12 hours. The antiarrhythmic effects of the primary drug's metabolites remain to be defined. Hemodynamic studies have shown mexiletine to have a lesser negative inotropic effect than procainamide or disopyramide. Although mexiletine as a single agent successfully suppresses 60 to 80% of spontaneous ventricular arrhythmias, it has lower efficacy in suppression of induced ventricular arrhythmias. Multiple studies have shown that as monotherapy mexiletine is effective in preventing the induction of ventricular tachycardia in approximately 20% of patients. When used in combination with a Class IA antiarrhythmic drug for suppression of induced ventricular arrhythmias, multiple investigators have reported greater efficacy. Neurological side effects (tremor, dizziness, memory loss) occur in approximately 10% of patients while gastrointestinal side effects (nausea, anorexia, gastric irritation) occur in up to 40% of patients. Proarrhythmia or other serious toxicity from the drug is uncommon.
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PMID:Mexiletine: pharmacology and therapeutic use. 218 14

The relationships between plasma mexiletine levels and the presence of ventricular arrhythmias and side effects were studied on patients from IMPACT (International Mexiletine and Placebo Antiarrhythmic Coronary Trial). 630 patients who had suffered a myocardial infarction were randomized between placebo and mexiletine. Plasma levels were measured 1 month after the beginning of treatment. Arrhythmia findings (presence or absence of premature ventricular contractions (PVCs), couplets, runs, bigeminy, trigeminy, multiformity and various combinations) were assessed from 24-h ambulatory ECG recordings. The empirical logistic transform was used for modeling the relationships. For all these variables, except the presence of PVCs, trigeminy and runs, the association with plasma level was significant: the higher the plasma level, the lower the rate of occurrence of the particular arrhythmia. This was true whether or not the patient had the arrhythmia at baseline. Analyses based on the same model showed a significant correlation between plasma level and tremor, constipation, sexual problems and the presence of at least one side effect. As the levels of mexiletine at which side effects become frequent are in the same range as those necessary to suppress arrhythmias, the therapeutic range is narrow and individual dose adjustment should preferably be made.
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PMID:Relationship between plasma mexiletine levels at steady-state. Presence of ventricular arrhythmias and side effects. 366 62

A new antiarrhythmic agent, 1-(2,6- dimethylphenoxy )-2-aminopropane (mexiletine), was investigated in 10 patients with chronic premature ventricular contractions (PVCs) to evaluate the antiarrhythmic efficacy and the pharmacokinetics after single intravenous, single oral and repeated oral dosings of mexiletine 150 mg. Mexiletine was well absorbed from the intestinal tract. The relative bioavailability was 83.2 +/- 8.9% (mean +/- S.E.). The time-concentration curve of mexiletine fitted in well with two-compartment open model. Elimination half-life, volume of distribution and plasma clearance were 10.54 +/- 0.26 h, 2.10 +/- 0.49 l/kg, 6.01 +/- 0.63 ml/min/kg, respectively. The computer-simulated time-concentration curves of multiple oral dosings , which were based on the kinetic parameters from single oral dosing, conformed well with measured concentrations. This might be applied to predict the plasma level of mexiletine. The steady state of plasma mexiletine level was reached 4-5 days after 450 mg/day dosings and ranged 0.75-2.18 micrograms/ml. In 6 of 10 patients, the frequency of PVCs was suppressed more than 75% as compared with the pre-medication value. Mexiletine was well tolerated at a dose of 450 mg/day. However, of 4 patients with the dose increased to 600 mg/day, the administration was ceased in three patients due to gastrointestinal symptoms and tremor. All of these adverse reactions disappeared when the administration was stopped. These results suggest that mexiletine is effective against ventricular arrhythmias and the dosage should be carefully adjusted. The prediction of plasma level would be applied to the dosage regimen of mexiletine.
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PMID:Pharmacokinetics and the antiarrhythmic effect of mexiletine in patients with chronic ventricular arrhythmias. 654 Jan 10

The antiarrhythmic efficacy of mexiletine was evaluated in 28 subjects with recurrent ventricular tachycardia or fibrillation (22 subjects) or with symptomatic complex ventricular ectopy (six subjects). In all, either the arrhythmia was refractory to other drugs, or such therapy was not tolerated. Response to mexiletine was assessed by continuous ECGs, and in five cases by programmed electrical stimulation. Mexiletine abolished the arrhythmia in 12 cases, but was not tolerated long-term in four. Mexiletine was ineffective in 10 subjects. Seven subjects had significant adverse reactions during short-term dosing; in six, mexiletine was discontinued because of adverse effects after the first few doses so efficacy was not evaluated. The most common adverse effects were nausea, tremor, and generalized malaise. We conclude that mexiletine is an effective antiarrhythmic in some patients with life-threatening ventricular arrhythmias refractory to conventional drugs. Adverse effects significantly limit its use.
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PMID:Mexiletine in refractory ventricular arrhythmias. 664 Oct 93