Medications and Drugs
Pharmacy Author: Annette O. Gbemudu, PharmD, MBA
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: quinidine
BRAND NAMES: Quinidine Gluconate, Quinidine Sulfate
Please Note: Brand name drugs (Quinaglute, Duraquin, Quinact, Quinidex, Cin-Quin,
Quinora) have been discontinued
DRUG CLASS AND MECHANISM: Quinidine is an antiarrhythmic medication that is
used to correct disturbances in the
rhythm of the heart (antiarrhythmic). Other
antiarrhythmic drugs within the same class include procainamide (for example,
Pronestyl) and disopyramide (for example, Norpace). This class of antiarrhythmics is
specifically called "Class I" antiarrhythmics, and they differ from other
antiarrhythmic drugs because they work by interfering with the sodium channel in
the membranes of cells. The sodium channel is part of the membrane (wall)
surrounding every cell that allows sodium to pass through into the cell, making
the cells (for example, muscle and nerve cells) excitable and, in the case of muscle
cells, able to contract. Thus, the flow of sodium through these channels is
necessary for the muscle cells of the heart to be stimulated to contract, and
Class I antiarrhythmics decrease the electrical stimulation of the muscle cells.
There are three actions that are responsible for quinidine's ability to stop
arrhythmias and prevent their recurrence. Quinidine decreases the speed of the
electrical current that travels through the heart muscle that causes the heart
muscle cells to contract. It also prolongs the period during which heart muscle
cells can become electrically stimulated to contract and prolongs the recovery
period after contraction during which the heart muscle cells cannot be
stimulated to contract.
Quinidine blocks the normal effect of the vagus nerve on the heart, causing
an increase in the rate at which the heart beats. Quinidine reduces the force of
contraction of heart muscle cells, and therefore may impair the pumping
efficiency of failing heart muscle as in congestive heart failure. Quinidine
blocks alpha-receptors on the muscle cells that surround arteries which relaxes
the muscle cells, lowers blood pressure ,and can cause excessively
low blood
pressure when combined with other drugs that also relax these muscle cells.
Quinidine was approved by the FDA in July 1950.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets: 200, 300, and 324 mg. Injections: 800 mg.
STORAGE: Quinidine should be stored at room temperature, 20-25 C (68-77 F).
It should be dispensed in well-closed, light-resistant container.
PRESCRIBED FOR: Quinidine is an antiarrhythmic drug used in the treatment of
abnormal heart rhythms, such as: atrial fibrillation, atrial flutter, and
ventricular arrhythmias such as paroxysmal ventricular tachycardia. Quinidine
also is used to treat malaria.
DOSING:
- For adults, the dosage range for quinidine gluconate is from 648 to
2592 mg/day.
- For adults, the dosage range for quinidine sulfate is from 400 to
4000 mg/day.
- For adults, the dosage range for quinidine gluconate injection is
400 to 2400 mg/day.
DRUG INTERACTIONS: Azole antifungals such as ketoconazole (Nizoral),
fluconazole (Diflucan), itraconazole (Sporanox PulsePak), voriconazole (VFEND),
posaconazole (Noxafil), and protease inhibitor/antiretroviral drugs such as
indinavir (Crixivan), and saquinavir (Invirase) should not be used with
quinidine since their concomitant use can increase quinidine levels by
inhibiting removal of quinidine by the liver. Increased quinidine levels can
increase the risk of quinidine toxicity and cardiac arrhythmias.
Phenothiazines such as thioridazine (Mellaril), an antipsychotic drug, and
tricyclic antidepressants such as amitriptyline (Elavil,
Endep) should not be used with
quinidine since they can cause cardiac arrhythmias, and their use with quinidine
increases the risk of cardiac arrhythmias.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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