April 28, 2017
Recommended Topic Related To:


"The U.S. Food and Drug Administration approved the Zilver PTX Drug-Eluting Peripheral Stent (Zilver PTX Stent), the first drug-eluting stent indicated to re-open a particular artery in the thigh (femoropopliteal artery) when narrowed or blocked a"...



Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)


Quinidine is an antimalarial schizonticide and an antiarrhythmic agent with Class la activity; it is the d-isomer of quinine, and its molecular weight is 324.43. Quinidine sulfate is the sulfate salt of quinidine; its chemical name is cinchonan-9-ol, 6'-methoxy-, (9S)-, sulfate(2:1) dihydrate.

its empirical formula is (C 20 H 24 N 2 O 2 ) 2 · H 2 SO 4 ·2H 2 O; and its molecular weight is 782.95, of which 82.9% is quinidine base.

Each Quinidex Extentabs® tablet contains 300 mg of quinidine sulfate (249 mg of quinidine base) in a formulation to provide extended release; the inactive ingredients are acacia, acetylated monoglycerides, calcium sulfate, carnauba wax, edible ink, FD&C Blue 2, gelatin, guar gum, magnesium oxide, magnesium stearate, polysorbates, shellac, sucrose, titanium dioxide, white wax, and other ingredients, one of which is a corn derivative. Tablets may also contain FD&C Red 40 and FD&C Yellow 6 Aluminum Lakes. These tablets comply with USP Drug Release Test 1.

What are the possible side effects of quinidine (Quin-G)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • vomiting and diarrhea;
  • ringing in the ears, hearing loss, severe dizziness;
  • feeling like you might pass out;
  • changes in vision, pain behind your eyes, increased sensitivity of your eyes to light;
  • white patches on your eyes;
  • cloudiness in the pupils or iris of your eyes;
  • a new or a worsening irregular...

Read All Potential Side Effects and See Pictures of Quinidex »

What are the precautions when taking quinidine (Quinidex)?

Before taking quinidine, tell your doctor or pharmacist if you are allergic to it; or to quinine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain types of heart disease (e.g., incomplete or complete heart block without an artificial pacemaker, torsades-type irregular heartbeats, digitalis toxicity), very low blood pressure, history of easy bruising/bleeding (thrombocytopenic purpura) with use of quinine or quinidine, severe muscle weakness (myasthenia gravis).

Before using this medication,...

Read All Potential Precautions of Quinidex »

Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.

Quinidex - User Reviews

Quinidex User Reviews

Now you can gain knowledge and insight about a drug treatment with Patient Discussions.

Here is a collection of user reviews for the medication Quinidex sorted by most helpful. Patient Discussions FAQs

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.

Heart Health

Get the latest treatment options.

Atrial Fibrillation Quiz