Product Overview
[Drug Name]
Generic Name: Theophylline Sustained-Release Tablets
Trade Name: Shufumei
English Name: Theophylline Sustained-Release Tablets
Chinese Pinyin: Chajianhuanshi Pian
[Ingredients]
The main ingredient is theophylline, chemically known as 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione hydrate.
[Properties]
This product is a white, oval tablet.
[Indications]
It is indicated for the relief of wheezing symptoms in conditions such as bronchial asthma, asthmatic bronchitis, and obstructive pulmonary emphysema. It can also be used for asthma caused by cardiogenic pulmonary edema.
[Dosage and Administration]
Oral administration. Do not crush or chew this product. For adults and children over 12 years old, the starting dose is 0.1g-0.2g (1-2 tablets), twice daily with 100ml of warm water in the morning and evening. The dosage may be adjusted based on the condition and efficacy, but the daily dose should not exceed 0.9g (9 tablets), taken in two divided doses. [Adverse Reactions] Theophylline toxicity often occurs at serum concentrations of 15-20 g/ml, especially at the beginning of treatment. Early symptoms include nausea, vomiting, irritability, and insomnia. When serum concentrations exceed 20 g/ml, tachycardia and arrhythmias may occur. When serum theophylline concentrations exceed 40 g/ml, fever, dehydration, and convulsions may occur. In severe cases, respiratory and cardiac arrest may occur, leading to death.
[Contraindications]
This product is contraindicated in patients with allergies, active peptic ulcers, and uncontrolled convulsive disorders.
[Precautions]
1. Like other theophylline sustained-release preparations, this product is not suitable for patients with status asthmaticus or acute bronchitis spasms.
2. Serum theophylline concentrations should be monitored regularly to ensure maximum efficacy without the risk of excessive blood concentrations.
3. This product is not suitable for patients with renal or hepatic impairment, patients over 55 years of age, especially men, and those with concomitant chronic lung disease, heart failure of any cause, and persistent fever. Patients taking certain medications and those with reduced theophylline clearance often experience significantly prolonged serum theophylline concentrations after discontinuation of concomitant medications. Dosage adjustments or longer dosing intervals should be considered as appropriate.
4. Theophylline preparations can cause arrhythmias and/or worsen existing arrhythmias; any changes in heart rate and/or rhythm should be monitored and investigated.
5. Use this product with caution in patients with hypoxemia, hypertension, or a history of peptic ulcers.
6. Keep out of reach of children.
[Use in Special Populations]
Precautions for Children:
Plasma clearance may be reduced and serum concentrations may be increased in neonates; therefore, use with caution. The safety and effectiveness of this product in children under 12 years of age are uncertain. Children over 12 years of age should follow a physician's advice when using this product.
Precautions During Pregnancy and Lactation:
This product can cross the placenta and be secreted into breast milk. Use with caution in pregnant, postpartum, and lactating women.
Elderly Precautions:
Due to decreased plasma clearance and increased potential toxicity in the elderly, use with caution in patients over 55 years of age.
[Drug Interactions]
1. Diltiazem and verapamil may interfere with theophylline metabolism in the liver. Concomitant use with this drug may increase theophylline's plasma concentration and toxicity.
2. Cimetidine may decrease the hepatic clearance of this drug. Concomitant use may increase theophylline's serum concentration and/or toxicity.
3. Certain antibacterial drugs, such as the macrolides erythromycin, roxithromycin, and clarithromycin, and the fluoroquinolones enoxacin, ciprofloxacin, ofloxacin, levofloxacin, clindamycin, and lincomycin, may decrease theophylline clearance and increase its plasma concentration. Erythromycin and enoxacin are particularly notable. When theophylline is used concomitantly with these drugs, the dosage should be appropriately reduced.
4. Phenobarbital, phenytoin, and rifampicin can induce hepatic enzymes and accelerate theophylline's hepatic clearance. Theophylline also interferes with phenytoin absorption, resulting in decreased plasma concentrations of both. Therefore, dosage adjustments should be made when used together.
5. Coadministration with lithium salts can increase lithium renal excretion, thus affecting the effect of lithium salts.
6. Coadministration with mexiletine can reduce theophylline clearance and increase plasma theophylline concentrations, necessitating dosage adjustments.
7. Coadministration with caffeine or other xanthines can increase their effects and toxicity.
[Pharmacological Actions]
This product has a direct relaxant effect on airway smooth muscle. Its mechanism of action is relatively complex. It was previously believed to be due to inhibition of phosphodiesterase, which increases intracellular cAMP levels. Recent experiments suggest that the bronchodilator effect of theophylline is partially due to the release of endogenous epinephrine and norepinephrine. Furthermore, theophylline is a purine receptor blocker, counteracting the constrictive effects of adenine and other drugs on the airways. Theophylline can enhance diaphragmatic contractility, especially when the diaphragm is weak, thus improving respiratory function.
[Storage]
Store in a dark, sealed container.
[Specifications]
0.1g x 24 tablets
[Packaging]
Box
[Expiration Date]
24 months
[Approval Number]
National Medicine Standard H44023791
[Manufacturer]
Guangzhou Maite Xinghua Pharmaceutical Factory Co., Ltd.
