quinidine, Quinidine Gluconate, Quinidine Sulfate
Annette (Gbemudu) Ogbru, PharmD, MBA
Annette (Gbemudu) Ogbru, PharmD, MBA
Dr. Gbemudu received her B.S. in Biochemistry from Nova Southeastern University, her PharmD degree from University of Maryland, and MBA degree from University of Baltimore. She completed a one year post-doctoral fellowship with Rutgers University and Bristol Myers Squibb.
Medical and Pharmacy Editor:
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.
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.
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.
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