Prajmaline
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Prajmaline (Neo-gilurythmal)
Mechanism
Prajmaline causes a resting block in the heart.[6] A resting block is the depression of a person's Vmax after a resting period. This effect is seen more in the atrium than the ventricle.[6] The effects of some Class I antiarrhythmics are only seen in a patient who has a normal heart rate (~1 Hz).[7] This is due to the effect of a phenomenon called reverse use dependence.[7] The higher the heart rate, the less effect Prajmaline will have.
Uses
The drug Prajmaline has been used to treat a number of cardiac disorders. These include: coronary artery disease,[8][9] angina,[8][9] paroxysmal tachycardia and Wolff–Parkinson–White syndrome.[1] Prajmaline has been indicated in the treatment of certain disorders where other antiarrhythmic drugs were not effective.[1]
Administration
Prajmaline can be administered orally,[9] parenterally[8] or intravenously.[8] Three days after the last dose, a limited effect has been observed. Therefore, it has been suggested that treatment of arrhythmias with Prajmaline must be continuous to see acceptable results.[1]
Pharmacokinetics
The main metabolites of Prajmaline are: 21-carboxyprajmaline and hydroxyprajmaline. Twenty percent of the drug is excreted in the urine unchanged.
Daily therapeutic dose is 40–80 mg. Distribution half-life is 10 minutes. Plasma protein binding is 60%. Oral bioavailability is 80%. Elimination half-life is 6 hours. Volume of distribution is 4-5 L/kg. [3]
Side Effects
There are no significant adverse side-effects of Prajmaline when taken alone and with a proper dosage.[1][8][9] Patients who are taking other treatments for their symptoms (e.g. beta blockers and nifedipine) have developed minor transient conduction defects when given Prajmaline.[8]
Overdose
An overdose of Prajmaline is possible. The range of symptoms seen during a Prajmaline overdose include: no symptoms, nausea/vomiting, bradycardia, tachycardia, hypotension, and death.[3]
Other Potential Uses
Due to Prajmaline's sodium channel-blocking properties, it has been shown to protect rat white matter from anoxia (82 +/- 15%).[10][11] The concentration used causes little suppression of the preanoxic response.[10][11]