quinidine

Brand names: Quin-Tab™Quinadure™Quinaglute®Quinidex®Quinora®

Chemical formula:

Drug Forms:
• Quinidine Sulfate Oral tablet (below)
• Quinidine extended-release tablets
• Quinidine Gluconate Oral tablet, extended-release
• Quinidine Gluconate Solution for injection
• Quinidine Sulfate Oral tablet, extended-release

Español:
• Sulfato de quinidina, Tableta oral
• Tabletas de liberación prolongada de quinidina
• Gluconato de quinidina, Tableta oral de liberación prolongada
• Gluconato de quinidina, Solución para inyección
• Sulfato de quinidina, Tableta oral de liberación prolongada

Quinidine Sulfate Oral tablet

What is this medicine?

QUINIDINE (KWIN i deen) is an antiarrhythmic drug. It helps make your heart beat regularly. This medicine also helps to slow rapid heartbeats. It is also used to treat certain types of malaria.
 
This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
•heart disease or previous heart attack
•kidney disease
•liver disease
•low blood pressure
•lung or breathing disease, like asthma
•myasthenia gravis
•you have a pacemaker
•an unusual or allergic reaction to quinidine, quinine, other medicines, foods, dyes, or preservatives
•pregnant or trying to get pregnant
•breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. You can take this medicine with or without food. Take your doses at regular intervals. Do not take your medicine more often than directed. Do not stop taking this medicine suddenly. This may cause serious, heart-related side effects. Your doctor will tell you how much medicine to take. If your doctor wants you to stop the medicine, the dose will be slowly lowered over time to avoid any side effects.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
•abarelix
•amiloride
•amoxapine
•apomorphine
•arsenic trioxide
•certain antifungal medicines like itraconazole or ketoconazole
•certain quinolone antibiotics
•cisapride
•droperidol
•haloperidol
•hawthorn
•levomethadyl
•maprotiline
•medicines for malaria like chloroquine and halofantrine
•medicines for mental depression such as tricyclic antidepressants
•mefloquine
•methadone
•other medicines to control heart rhythm
•pentamidine
•phenothiazines like chlorpromazine, mesoridazine, thioridazine
•pimozide
•ranolazine
•sertindole
•vardenafil
•voriconazole
•ziprasidone

This medicine may also interact with the following medications:
•acetazolamide
•antacids
•barbiturates, like phenobarbital
•cimetidine
•diuretics
•medicines for high blood pressure or angina
•medicines for surgery that relax muscles or block pain
•methazolamide
•phenytoin
•prescription pain medicines like codeine and hydrocodone
•rifampin
•sodium bicarbonate
•warfarin

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Visit your doctor or health care professional for regular checks on your progress. Wear a medical ID bracelet or chain, and carry a card that describes your disease and details of your medicine and dosage times.

Check your blood pressure and pulse rate regularly. Ask your health care professional what your blood pressure and pulse rate should be, and when you should contact him or her. Your doctor or health care professional also may schedule regular blood tests and electrocardiograms to check your progress.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol may interfere with the effect of this medicine. Avoid alcoholic drinks.

This medicine can make you more sensitive to the sun. Keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and use sunscreen. Do not use sun lamps or tanning beds/booths.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
•breathing problems
•changes in vision
•confusion
•feeling faint or lightheaded
•fever
•headache
•irregular heartbeat
•nausea, vomiting
•pain on swallowing
•skin rash, peeling or loose skin
•ringing in the ears
•unusual bruising or bleeding
•unusually weak or tired

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
•diarrhea
•flushing of the skin with intense itching
•heartburn
•loss of appetite
•stomach pain

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light and moisture. Keep container tightly closed. Throw away any unused medicine after the expiration date.

Last updated: 4/8/2003 4:26:00 PM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

The dextrorotatory isomer of quinine, used in treatment of cardiac arrhythmias. Several salts are used, including the gluconate, sulfate and bisulfate.

Quinidine
Systematic (IUPAC) name
(9S)-6'-methoxycinchonan- 9-ol
Identifiers
CAS number	56-54-2
ATC code	C01BA01
PubChem	5953
DrugBank	APRD00136
Chemical data
Formula	C20H24N2O2
Mol. mass	324.417 g/mol
Synonyms	(2-ethenyl- 4-azabicyclo [2.2.2] oct- 5-yl)- (6-methoxyquinolin- 4-yl)- methanol, 6'-methoxy- α-(5-vinyl- 2-quinuclidinyl)- 4-quinoline methanol, (S)- (6-methoxyquinolin- 4-yl) ((2R,4S,5R)- 5-vinylquinuclidin- 2-yl) methanol
Pharmacokinetic data
Bioavailability	70-80%
Metabolism	50-90% Hepatic
Half life	6-8h
Excretion	Renal
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	Oral
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Quinidine is a pharmaceutical agent that acts as a class I antiarrhythmic agent (Ia) in the heart. It is a stereoisomer of quinine, originally derived from the bark of the cinchona tree.

Contents 1 Mechanism 2 Elimination 3 Side effects 4 Other uses 5 References 6 External links 7 See also

Mechanism

Like all other class I antiarrhythmic agents, quinidine primarily works by blocking the fast inward sodium current (I_Na). Quinidine's effect on I_Na is known as a use dependent block. This means that at higher heart rates, the block increases, while at lower heart rates the block decreases. The effect of blocking the fast inward sodium current causes the phase 0 depolarization of the cardiac action potential to decrease (decreased V_max).

Quinidine also blocks the slowly inactivating tetrodotoxin-sensitive Na current, the slow inward calcium current (I_Ca), the rapid (I_Kr) and slow (I_Ks) components of the delayed potassium rectifier current, the inward potassium rectifier current (I_KI), the ATP-sensitive potassium channel (I_KATP) and I_to.

At micromolar concentrations, quinidine inhibits Na⁺/K⁺-ATPase by binding to the same receptor sites as the digitalis glycosides such as ouabain.

The effect of quinidine on the ion channels is to prolong the cardiac action potential, thereby prolonging the QT interval on the surface ECG.

Other ECG effects include a wide notched P wave, wide QRS complex, depressed ST segment, and U waves. These are the results of both slowed depolarization and repolarization.

Elimination

The half life of oral quinidine is 6 to 8 hours, and it is eliminated by the cytochrome P450 system in the liver. About 20% is excreted unchanged via the kidneys.

Side effects

Quinidine is also an inhibitor of the cytochrome P450 enzyme 2D6, and can lead to increased blood levels of lidocaine, Beta blockers, opioids, and some anti-depressants.

Quinidine also inhibits the transport protein P-glycoprotein and so can cause some peripherally acting drugs such as loperamide to have CNS side effects such as respiratory depression if the two drugs are co-administered.^[1]

Quinidine-induced thrombocytopenia (low platelet count) is mediated by the immune system, and may lead to thrombocytic purpura. Discovered by a Danish Merchant seaman with AF who took quinine for malaria prophylaxis during trips to India.  He noted his pulse was regular while in India but irregular at home. Chichonism describes tinnitus and hearing loss with quinidine excess. 

Quinidine can cause thrombocytopenia, granulomatous hepatitis, myasthenia gravis, and torsades de pointes and for that reason is not used much today.  Torsades can occur after the first dose.�

Quinidine intoxication can lead to a collection of symptoms collectively known as cinchonism with tinnitus (ringing in the ears) being among the most characteristic and common symptoms of this toxicity syndrome.

Other uses

Intravenous quinidine is also indicated for treatment of Plasmodium falciparum malaria.^[2] However,quinidine is not considered the first line therapy for P. falciparum. The recommended treatments for plasmodium falciparum according to the Toronto Notes 2008 are quinine (not to be confused with "quinidine") + doxycycline combination or atovaquone/proguanil (Malarone TM).

Quinidine sulphate is used in the treatment of atrial fibrillation in the horse, although due to the risk of causing arrhythmias, the patient must be medicated before and after with the anti-arrhythmic drug digoxin.

Quinidine-based ligands are used in AD-mix-β for Sharpless asymmetric dihydroxylation.

References

1. ^ Sadeque AJ, Wandel C, He H, Shah S, Wood AJ (2000). "Increased drug delivery to the brain by P-glycoprotein inhibition". Clin. Pharmacol. Ther. 68 (3): 231–7. doi:10.1067/mcp.2000.109156. PMID 11014404. 
2. ^ "From the Centers for Disease Control and Prevention. Availability and use of parenteral quinidine gluconate for severe or complicated malaria". JAMA 285 (6): 730. February 2001. PMID 11236771. http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=11236771. 

External links

• MedlinePlus
• Poisons Information Monograph

See also

• Antiarrhythmic agents
• Cardiac action potential

v • d • e Antiarrhythmic agents (C01B) Channel blockers class I (Na+ channel blockers) class Ia (Phase 0→ and Phase 3→) Procainamide # • Quinidine # • Ajmaline • Disopyramide • Prajmaline • Sparteine class Ib (Phase 3←) IV (Lidocaine #) • enteral (Mexiletine, Tocainide, Aprindine) class Ic (Phase 0→) Encainide • Flecainide • Lorcainide • Moricizine • Propafenone class III (Phase 3→, K+ channel blockers) Amiodarone • Bretylium • Bunaftine • Dofetilide • Ibutilide • Nifekalant • Sotalol • Tedisamil • E-4031 class IV (Phase 4→, Ca2+ channel blockers) Verapamil # • Diltiazem Receptor agonists and antagonists class II (Phase 4→, β blockers) Propranolol • Nadolol • Pindolol • cardioselective (Atenolol, Metoprolol, Acebutolol, Esmolol) A1 agonist Adenosine M2 muscarinic antagonist: Atropine • Quinidine • Disopyramide muscarinic agonist: Digoxin α receptors Quinidine • Verapamil • Amiodarone • Bretylium Ion transporters Na+ / K+-ATPase Digoxin # = WHO-EM

v • d • e Antiparasitics – antiprotozoal agents – Chromalveolate antiparasitics (P01) Alveolate Apicomplexa Conoidasida/ (Coccidiostats) Cryptosporidiosis thiazole (Nitazoxanide) Isosporiasis Co-trimoxazole# Toxoplasmosis Pyrimethamine • Sulfadiazine Aconoidasida Malaria Hemozoin inhibitors Qs: Amino- 4-Aminoquinoline (Amodiaquine#, Chloroquine#, Hydroxychloroquine) • 8-Aminoquinoline (Primaquine#, Pamaquine) Qs: Methanol- Mefloquine# • Quinine# • Quinidine Other Halofantrine • amyl alcohol (Lumefantrine#) Antifolates DRIs 2,4-Diaminopyrimidines (Pyrimethamine#) • biguanides (Proguanil#, Cycloguanil, Chlorproguanil) DSIs Sulfadoxine# PfATP6 inhibitor Artemisinin (Artemether#, Artesunate#, Artenimol, Arteether/Artemotil, Dihydroartemisinin) Other aminoacridine (Quinacrine) • ubiquinone analogue (Atovaquone) • tetracycline (Doxycycline#) Combinations Coartem • Lapdap • CDA Babesiosis Clindamycin Ciliophora Balantidiasis: Tetracycline Heterokont Blastocystosis: Metronidazole #WHO-EM. ‡Withdrawn from market. CLINICAL TRIALS: †Phase III. §Never to phase III see also diseases

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