Theo-24 Sr is bronchodilator of the methylxanthines group. Theophylline has a stimulating effect on the central nervous system, myocardium and skeletal muscles. It causes relaxation of smooth muscles. A moderate diuretic effect has also observed. Bronchodilatory effect associated with the effect on bronchial smooth muscles is the most pronounced at the initial bronchoconstriction. The mechanism of theophylline action is based on its ability to inhibit the enzyme PDE and increase the concentration of cyclic 3-, 5-AMP in tissues. cAMP affects the β-receptors of bronchial smooth muscle. The bronchodilatory effect of theophylline is ultimately analogous to the action of sympathomimetics. This substance stimulates adrenaline secretion by the adrenal glands and can have a direct effect on adenine receptors in some tissues. Like β-sympathomimetic drugs, it inhibits the release of anaphylaxis mediators from sensitized cells.
This drug stimulates the respiratory center. It causes an increase in the stroke volume of blood and the work of the heart left ventricle without a significant change in heart rate. Peripheral vascular resistance decreases with the expansion of blood vessels (including coronary). Cerebral circulation may decrease, while blood flow to peripheral tissues increases. Theophylline, affecting the transport of Ca2 + in skeletal muscle, contributes to their reduction. The diuretic effect of theophylline is more expressed than that of other purine alkaloids, but its action is short. The diuretic effect is achieved due to improved renal circulation, mobilization of sodium chloride from the tissues and inhibition of glomerular reabsorption. It causes a slight stimulation of gastric secretion.
It is used in the basic therapy of asthma. In addition to the bronchodilator effect, theophylline increases mucociliary clearance, reduces pressure in the pulmonary vessels, inhibits the release of mediators of anaphylactic reactions. It potentiates the effect of β2-adrenomimetics.
Indications for use
- Bronchial asthma;
- Symptomatic treatment of bronchospasm of various etiologies (including in chronic obstructive pulmonary diseases, chronic bronchitis, pulmonary emphysema);
- Pulmonary hypertension;
- Pulmonary heart;
- Nocturnal paroxysmal apnea.
Dosage and administration
The drug is administered orally washed down with a sufficient amount of water. Dosing regimen is selected individually.
The maximum daily dose in adults is 15 mg/kg.
For non-smoking adult patients with weight 60 kg or over, the initial dose is 200 mg per day, then 200 mg 2 times per day.
In patients with a body weight less than 60 kg, the initial single dose is 100 mg in the evening, then 100 mg 2 times a day. Treatment begins with smaller doses, which gradually, with an interval of 1-2 days, increase (by 100-200 mg/day) to obtain the maximum therapeutic effect, with poor tolerance – decrease.
The dose depends on the nature of the disease, the age and body weight. If necessary, the appointment of high doses of treatment is carried out under the control of theophylline concentration in the blood (therapeutic concentration in the range of 10-15 μg/ml):
- at a concentration of 20-25 μg/ml, it is necessary to reduce the daily dose by 10%;
- 25-30 µg/ml – by 25%;
- above 30 mcg/ml – the daily dose is reduced by 2 times.
Repeated control is carried out after 3 days. If the concentration is too low, the daily dose is increased by 25% at 3-day intervals. With the stabilization of the patient’s condition on the background of the reception in high doses, it is necessary to do test every 6-12 months.
Maintenance dose for adults with a body weight over 60 kg – 600 mg/day, less than 60 kg – 400 mg/day.
For smokers with weight more than 60 kg, the daily dose is 600 mg in the evening and 300 mg in the morning, with a body weight of less than 60 kg – 400 mg in the evening and 200 mg in the morning.
For patients with diseases of the cardiovascular system and abnormal liver function: with a body weight of more than 60 kg, the daily dose is 400 mg, with a body weight of less than 60 kg – 200 mg. Reduction of the daily dose is required in patients with severe heart lesions, liver, viral infections, in elderly patients.
Overdose
Symptoms: decreased appetite, gastralgia, diarrhea, nausea, emesis (including blood), gastrointestinal bleeding, tachypnea, facial flushing, tachycardia, ventricular fibrillation, insomnia, motor agitation, anxiety, photophobia, tremors, convulsions.
In severe poisoning, epileptoid seizures, hypoxia, metabolic acidosis, hyperglycemia, hypokalemia, decreased blood pressure, skeletal muscle necrosis, confusion, renal failure with myoglobinuria can develop.
Treatment: withdrawal of the drug, gastric lavage, the appointment of activated carbon, laxative drugs, forced diuresis, hemosorption, plasma sorption, symptomatic therapy.
For stopping the seizure – diazepam intravenous, 0.1-0.3 mg/kg (not more than 10 mg).
With severe nausea and vomiting – metoclopramide or ondansetron (intravenous).
Side effects
- Heartburn;
- Nausea;
- Vomiting;
- Exacerbation of peptic ulcer;
- Epigastric pain;
- Diarrhea.
In the case of prolonged use, Theo-24 Sr can cause the following side effects:
- loss of appetite;
- headache;
- dizziness;
- irritability;
- anxiety;
- insomnia;
- increased reflex excitability;
- clonic and tonic convulsions, tremor;
- heartbeat;
- tachycardia;
- arrhythmia;
- extrasystole;
- flushing;
- hypotension;
- circulatory disorders;
- ventricular arrhythmia;
- increased frequency of strokes;
- pain in the heart;
- tachypnea;
- increased diuresis;
- hematuria;
- albuminuria;
- alopecia;
- hypoglycemia, hypokalemia;
- skin itch, rash.
Contraindications
- Hypersensitivity to theophylline (including to other xanthine derivatives) or to additional drug components;
- Epilepsy and other convulsive states;
- Hyperthyroidism;
- Acute myocardial infarction;
- Subaortic stenosis;
- Extrasystole, severe tachyarrhythmias, severe hypertension;
- Hemorrhagic stroke;
- Gastritis with increased acidity, gastrointestinal bleeding in recent history;
- Peptic ulcer and duodenal ulcer in the acute phase;
- Retinal hemorrhage;
- Children and adolescents up to 18 years;
- Pregnancy.
Before buying Theo-24 Sr consult a doctor to avoid severe side effects.
Drug interactions
Theo-24 Sr potentiates the bronchodilator effect of beta2-adrenomimetics, which allows the use of the latter in smaller doses. This substance increases the clearance of lithium and pyridoxine with a concomitant appointment, so their effectiveness decreases with a constant concentration of the drug in the blood plasma.
The theophylline concentration in the blood decreases with simultaneous use with phenobarbital, rifampicin, isoniazid, carbamazepine, sulfinpyrazone, phenytoin. This substance concentration in the blood increases with the simultaneous use of antibiotics from the group of macrolides, allopurinol, beta-blockers, cimetidine, hormonal oral contraceptives, isoprenaline, lincomycin.
Theophylline can potentiate hypokalemia caused by the action of stimulants β2-adrenoreceptors, corticosteroids and diuretics.
Pregnancy and lactation
During pregnancy (especially in the first trimester), theophylline is prescribed only if the intended benefit to the mother exceeds the possible risk to the fetus. Prescription of the drug during pregnancy (the first trimester and the end of the pregnancy course) is possible only under strict indications.
In appointing the drug during lactation, remember that theophylline is excreted in breast milk. It is not recommended to take the drug during lactation. If necessary to take this drug a woman should stop breastfeeding.