Product Overview
[Drug Name]
Generic Name: Theophylline Sustained-Release Tablets
Trade Name: Linuo Pharmaceutical Theophylline Sustained-Release Tablets 0.1g*24 Tablets
Pinyin Code: LiNuoZhiYaoChaJianHuanShiPian 0.1g*24 Tablets
[Main Ingredient]
The main ingredient of this product is theophylline, chemically known as 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione monohydrate. Molecular formula: C7H8N4O2; H2O; Molecular weight: 198.18.
[Properties]
This product is a white or slightly yellow film-coated tablet.
[Indications/Main Functions]
This product 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.
[Specifications]
0.1g*24 tablets
[Dosage and Administration]
Oral administration. Do not crush or chew. 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 can be adjusted based on the patient's condition and efficacy, but the daily dose should not exceed 0.9g (9 tablets) in two divided doses.
[Adverse Reactions]
Theophylline toxicity typically occurs at serum concentrations of 15-20μg/ml, especially at the beginning of treatment. Early symptoms include nausea, vomiting, irritability, and insomnia. When serum concentrations exceed 20μg/ml, tachycardia and arrhythmias may occur. When serum theophylline concentrations exceed 40μg/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.
[Drug Interactions]
1. Diltiazem and verapamil may interfere with theophylline metabolism in the liver. Coadministration with this drug may increase theophylline's blood concentration and toxicity.
2. Cimetidine may reduce the hepatic clearance of this drug. Coadministration 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 reduce theophylline clearance and increase its blood concentration, especially erythromycin and enoxacin. When theophylline is used with these drugs, the dose should be appropriately reduced.
4. Phenobarbital, phenytoin, and rifampicin may induce hepatic enzymes, accelerating theophylline's hepatic clearance. Theophylline also interferes with phenytoin absorption, resulting in decreased plasma concentrations of both. Therefore, the dose should be adjusted when used together.
5. Coadministration with lithium salts may increase lithium excretion by the kidneys. This may affect the effects of lithium salts.
6. Concomitant use with mexiletine may reduce theophylline clearance and increase plasma theophylline concentrations, necessitating dose adjustment.
7. Concomitant use with caffeine or other xanthines may increase their effects and toxicity.
[Precautions]
1. Like other theophylline extended-release preparations, this product is not suitable for patients with status asthmaticus or acute bronchospasm.
2. Serum theophylline concentrations should be monitored regularly to ensure maximum efficacy without the risk of excessive blood concentrations.
3. Patients with renal or hepatic impairment, those over 55 years of age, especially men, and those with concomitant chronic lung disease, patients with heart failure of any cause, and patients with persistent fever. Patients taking certain medications and those with reduced theophylline clearance may experience significantly prolonged serum theophylline concentrations after discontinuation of concomitant medications. The dose should be adjusted or the dosing interval extended as appropriate.
4. This preparation may induce arrhythmias and/or worsen existing arrhythmias; any changes in the patient's heart rate and/or rhythm should be monitored and investigated.
5. This product should be used with caution in patients with hypoxemia, hypertension, or a history of peptic ulcers.
[Pediatric Use]
Plasma clearance may be reduced in neonates, leading to increased serum concentrations. Caution is advised when using this product. The safety and efficacy of this product in children under 12 years of age are uncertain. Children over 12 years of age should follow a physician's advice.
[Elderly Use]
Due to decreased plasma clearance and increased potential toxicity in the elderly, caution should be exercised in patients over 55 years of age.
[Overdose]
This study has not been conducted and no reliable references are available.
[Pharmacology and Toxicology]
This product has a direct relaxant effect on airway smooth muscle. Its mechanism of action is complex, previously believed to be through 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 agonists on the airways. Theophylline can enhance the contraction force of the diaphragm, especially when the diaphragm contraction is weak, so it is beneficial to improve respiratory function.
