What Is Quinidine?
Quinidine is a white crystalline powder alkaloid. Its IUPAC name is (S)-(6-Methoxyquinolin-4-yl)[(1S,2R,4S,5R)-5-vinylquinuclidin-2-yl]methanol. It is also known as conquinine, among other names.
The chemical formula of quinidine is C20H24N2O2 and its molecular weight is 324.42. Its CAS number is 56-54-2.
Uses of Quinidine
Quinidine is an alkaloid extracted from the bark of the genus cinchona.
1. Pharmaceutical Field
Because of its potent anti-arrhythmic action, quinidine has long been used in the pharmaceutical field as a treatment for atrial and ventricular arrhythmias. In the myocardium, it attenuates excitability by inhibiting the flow of sodium and potassium across the cell membrane. This attenuating effect on excitability results in the suppression of irregular contractions of the myocardium.
2. Antimalarial Action
By binding to heme polymer in the acid-fed vacuole of the parasite and inhibiting polymerization by heme polymerase enzyme, it exerts its antimalarial activity mainly by acting as an intraerythrocytic mitotic agent. However, it is not used as a first-line drug when administered alone, but in combination with doxycycline or with other drugs.
3. Contraindications
It is contraindicated and therefore not available for use in patients with stimulated conduction defects, severe congestive heart failure, or symptoms of hyperkalemia. A number of other concomitant medications have been reported to be prohibited.
4. Chemical Reagents
Quinidine derivatives are used as ligands for the sharpless asymmetric dihydroxylation reagent AD-mix-β.
Properties of Quinidine
Quinidine has a melting point of 174°C and is solid at room temperature. It is very soluble in methanol, soluble in alcohol, ether, and chloroform, and insoluble in petroleum ether.
The acid dissociation constant (pKa), one of the quantitative indicators of acid strength, is 8.56. A smaller pKa indicates a stronger acid.
Other Information on Quinidine
1. Production Process of Quinidine
Most of the quinidines currently on the market are produced by isomerization of quinine. From natural sources, quinidine is obtained from the mother liquor that remains after the quinine has been removed from an extract of the genus cinnamomum. It can be purified by recrystallization in water or alcohol.
2. Precautions for Handling and Storage
Handling
Avoid contact with strong oxidizers. Use in a draft chamber with local exhaust ventilation and wear personal protective equipment.
In case of fire
Quinidine is nonflammable and will not itself burn. However, thermal decomposition may produce nitrogen oxide gas. Use water spray, foam, powder extinguisher, carbon dioxide, dry sand, etc. to extinguish fire.
If adhered to skin
Care should be taken to prevent adhesion to skin. Always wear protective clothing such as a lab coat or work clothes and protective gloves when using the product. Never roll up the sleeves of protective clothing to avoid skin exposure.
In the event of skin contact, it is important to wash off with soap and plenty of water. If on clothing, remove all contaminated clothing and isolate. If symptoms persist, medical attention is required.
In case of eye contact
Always wear protective glasses or goggles when using the product. In the unlikely event of eye contact, rinse carefully with water for several minutes. If wearing contacts, remove them if they can be easily removed and rinse thoroughly. Immediate medical attention is required.
Storage
Store in a tightly closed, light-shielded glass container. A well-ventilated, cool place, away from direct sunlight, is desirable.