Mechanism of Drug Action -Drug Channel Interactions

In drug channel interaction, drug interfere with the flow of ions through the channels specific for these ions. These include the Na+, K+,Ca++ and Cl- channels. Examples include:

1. Sodium Channels:-      Quindine Procainamide, Local anesthetics
2. Calcium channels:-      Nifedipine, Verapamil, Diltiazem
3. Potassium Channels:-   Amiodarone, sulfonylureas
4. Chloride Channels:-     Benzodiazepines

1. Sodium Channels

Sodium channel drugs are used in cardiac arrhythmias and act by blocking the sodium channels. These include the local anesthetics which produce anesthesia in a localized area. Thus depolarization does not take place and there is no nerve conduction in that localized area.

2. Calcium channels

Calcium channel drugs are used in the treatment of hypertension and arrhythmias. They block the voltage gated calcium channels and release the vascular stiffness.

3. Potassium channels

Potassium channel drugs include amiodarone used in arrhythmias and block potassium channels. Thus there is a prolonged refractory period. Sulfonylureas are antidiabetic and block the ADP mediated potassium channels in the beta cells of pancreas.

4. Chloride channels

Chloride channel  drugs include benzodiazepines which produce sedation, used in epilepsy and are muscle relaxants. They increase the entry of chloride ions through the chloride channels causing hyper polarization.

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