Quinidine

Functional Indications:
Mainly suitable for maintenance treatment of atrial fibrillation or atrial flutter after electrical conversion. Although it is effective for premature atrial contractions, paroxysmal supraventricular tachycardia, preexcitation syndrome with supraventricular arrhythmias, premature ventricular contractions, and ventricular tachycardia, it also has the effect of converting atrial fibrillation or atrial flutter. , but due to many adverse reactions, it is now rarely used.

Dosage:
There may be differences in the usage and dosage of different dosage forms and specifications of this product. Please read the specific drug instructions for use, or follow your doctor’s advice. Quinidine Sulfate Tablets: 1. Adults should try taking 0.2g first to observe whether there is any allergic or idiosyncratic reaction. 2. Commonly used dosage for adults: 0.2-0.3g once, 3-4 times a day. For the conversion of atrial fibrillation or atrial flutter, 0.2g on the first day, once every 2 hours, for 5 consecutive times; if there are no adverse reactions, increase to 0.3g each time on the second day, and 0.4g each time on the third day. Once every 2 hours, 5 times in a row. The total daily amount should not exceed 2.4g. After restoring sinus rhythm, change to a maintenance dose of 0.2-0.3g once, 3-4 times a day. 3. Maximum dosage for adult prescription: 3g per day (generally not more than 2.4g per day), should be given in divided doses.

Adverse reactions:
This product has a low therapeutic index, and approximately 1/3 of patients experience adverse reactions. 1. Cardiovascular: This product has a proarrhythmic effect, causing cardiac arrest and conduction block, which is more common in patients with existing heart disease. Premature ventricular contractions, ventricular tachycardia and ventricular fibrillation can also occur. Prolongation of the P-R interval and widening of the QRS complex may appear on the electrocardiogram, which is generally related to dose. It can significantly prolong the Q-T interval of the electrocardiogram, induce ventricular tachycardia (torsades) or ventricular fibrillation, which may spontaneously stop repeatedly and be accompanied by syncope. This effect has nothing to do with the dose and can occur in the blood. When the drug concentration is still within the therapeutic range or below. This product can dilate blood vessels and cause hypotension, and vasculitis may occur in some cases. 2. Gastrointestinal adverse reactions: very common. These include nausea, vomiting, cramps, diarrhea, decreased appetite, lobular hepatitis, and esophagitis. 3. Cinchona reaction: can produce tinnitus, gastrointestinal disorders, heart palpitations, convulsions, headaches and flushing. Visual impairment such as blurred vision, photophobia, diplopia, color vision impairment, mydriasis, scotoma and night blindness. Hearing impairment, fever, local edema, dizziness, tremor, excitement, coma, worry, and even death. Generally related to dose. 4. Idiosyncratic reactions: dizziness, nausea, vomiting, cold sweats, shock, bruising, respiratory depression or cessation. Regardless of dosage. 5. Allergic reactions: various rashes, especially urticaria and itching, fever, asthma, hepatitis and collapse. Regardless of dose. 6. Muscle: aggravates myasthenia gravis. Increase CPK enzyme. 7. Blood system: thrombocytopenia, acute hemolytic anemia, granulocytopenia, left shift in white blood cell classification, and neutropenia.

Medication contraindications:
It is contraindicated in those who are allergic to this drug or who have used this drug to cause thrombocytopenic purpura. This drug is contraindicated in patients with second- or third-degree atrioventricular block and sick sinus syndrome without pacemaker protection.