Dilatrend Drug Interactions





Full Prescribing Info
Drug Interactions
(See also Precautions.)
Pharmacokinetic Interactions: Digoxin: Digoxin concentrations are increased by about 15% when digoxin and carvedilol are administered concomitantly. Both digoxin and carvedilol slow AV conduction. Increased monitoring of digoxin levels is recommended when initiating, adjusting or discontinuing carvedilol.
Insulin or Oral Hypoglycemics: Agents with β-blocking properties may enhance the blood sugar-reducing effect of insulin and oral hypoglycemics. The signs of hypoglycemia may be masked or attenuated (especially tachycardia). In patients taking insulin or oral hypoglycemics, regular monitoring of blood glucose is therefore recommended.
Inducers and Inhibitors of Hepatic Metabolism: Rifampicin reduced plasma concentrations of carvedilol by about 70%. Cimetidine increased AUC by about 30% but caused no change in Cmax. Care may be required in those patients receiving inducers of mixed function oxidases eg, rifampicin, as serum levels of carvedilol may be reduced or inhibitors of mixed function oxidases eg, cimetidine, as serum levels of carvedilol may be increased.
However, based on the relatively small effect of cimetidine on carvedilol drug levels, the likelihood of any clinically important interaction is minimal.
Catecholamine-Depleting Agents: Patients taking both agents with β-blocking properties and a drug that can deplete catecholamines (eg, reserpine and monoamine oxidase inhibitors) should be observed closely for signs of hypotension and/or severe bradycardia.
Cyclosporin: Modest increases in mean trough cyclosporin concentrations were observed following initiation of carvedilol treatment in 21 renal transplant patients suffering from chronic vascular rejection. In about 30% of patients, the dose of cyclosporin had to be reduced in order to maintain cyclosporin concentrations within the therapeutic range, while in the remainder no adjustment was needed. On average, the dose of cyclosporin was reduced about 20% in these patients. Due to wide interindividual variability in the dose adjustment required, it is recommended that cyclosporin concentrations be monitored closely after initiation of carvedilol therapy and that the dose of cyclosporin be adjusted as appropriate.
Verapamil, Diltiazem or Other Antiarrhythmics: In combination with carvedilol can increase the risk of AV conduction disturbances (see Precautions).
Pharmacodynamic Interactions: Clonidine: Concomitant administration of clonidine with agents with β-blocking properties may potentiate blood pressure- and heart rate-lowering effects. When concomitant treatment with agents with β-blocking properties and clonidine is to be terminated, the β-blocking agent should be discontinued first. Clonidine therapy can then be discontinued several days later by gradually decreasing the dosage.
Calcium-Channel Blockers (See Precautions): Isolated cases of conduction disturbance (rarely with hemodynamic compromise) have been observed when carvedilol is co-administered with diltiazem. As with other agents with β-blocking properties, if carvedilol is to be administered orally with calcium-channel blockers of the verapamil or diltiazem type, it is recommended that ECG and blood pressure be monitored.
As with other agents with β-blocking activity, carvedilol may potentiate the effect of other concomitantly administered drugs that are antihypertensive in action (eg, α1-receptor antagonists) or have hypotension as part of their adverse effect profile.
Careful attention must be paid during anesthesia to the synergistic negative inotropic and hypotensive effects of carvedilol and anesthetic drugs.
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