Generic Singulair Montelukast

Singulair (generic)

Drugs name: Montelukast

Manufacturer: Cipla

International non-proprietary name : Montelukast

Action mechanism

Generic Singulair (montelukast) inhibits cysteinyl  of leukotriene receptor of  the respiratory tract epithelium (Leukotriene Receptor Antagonists (LTRAs) and thereby simultaneously possesses the ability to inhibit bronchoconstriction due to inhalation of cysteinyl-leukotriene LTD4 in patients with bronchial asthma. The dose of montelukast   5 mg is sufficient for relief of bronchoconstriction induced by LTD4. Generic Singulair causes bronchodilation within 2 hours after ingestion and may enhance bronchodilation caused by β2-agonists.

How generic Singulair is absorbed, metabolized and eliminated out of the organism?

Pharmacokinetics

Absorption

Generic Singulair (Montelukas) is rapidly and almost completely absorbed after oral administration. Food intake does not affect the bioavailability and maximum plasma concentrations (Cmax) of generic Singulair. In patients which took generic Singulair 10mg  Cmax is achieved in 3 hours. Oral bioavailability is 64%. The bioavailability of generic  Singulair of different dosages is different.

Distribution

More than 99% of Montelukast binds to plasma proteins. The volume of distribution of montelukast averages 8.11 liters.

Metabolism

Montelukast is actively metabolized in the liver. It is expected that the process of metabolism of montelukast involved isozymes of cytochrome P450 CYP (3A4 and 2C9). In therapeutic concentrations montelukast does  not inhibit cytochrome P450 isozymes CYP: 3A4, 2C9, 1A2, 2A6, 2C19 and 2D6.

Elimination

The Clearance of montelukast in healthy adults is in average 45 ml/min. After oral  oral application of montelukast, 86% of the amount is excreted with the feces within 5 days and less than 0,2% with the urine. Montelukast and its metabolites are excreted almost exclusively via the bile.

Half-life period pf montelukast in young healthy adults ranges from 2,7 to 5,5 hours. The pharmacokinetics of montelukast remains almost linear at oral doses above 50 mg. In application of generic Singulair in the morning and evening hours pharmacokinetic differences were not observed.

Pharmacokinetics in different patient's groups

Gender

The pharmacokinetics of montelukast in women and men is similar.

Older patients

When generic Singulair 10mg is administered once daily pharmacokinetic indexes and bioavailability are similar in elderly and young patients.

Liver failure

In patients with hepatic insufficiency of mild to moderate severity and clinical manifestations of liver cirrhosis there were observed slowing of montelukast metabolism, an increase in areas under the pharmacokinetic curve "concentration-time» (AUC) by approximately 41% after a application of single dose 10 mg. The correction of montelukast dose for patients  with hepatic insufficiency of mild to moderate severity is not required. Generic Singulair is not recommended for patients with severe hepatic insufficiency.

Race

There are no any significant differences in  pharmacokinetic effects in patients of different races.

Renal failure

Because generic Singulair (montelukast) is no excreted with the urine, the pharmacokinetics of montelukast in patients with renal insufficiency has not been evaluated. The correction of Montelukast dose for this category of patients is not required.

Indication

Generic Singulair is indicated in prophylaxis and prolonged treatment of bronchial asthma in adults and children beginning from 14 years of age including daily and night symptoms of the disease, treatment of aspirin-dependent patients with bronchial asthma and prevention of bronchospasm caused by physical overload.

Generic Singulair is used to a arrest daily and night symptoms of seasonal allergic rhinitis (in adults and children over 6 years of age) and all year round allergic rhinitis (in adults and children over 14 years of age).

Contraindications

Generic Singulair should not be taken in children under 14 years of age and patients with known hypersensitivity to any of the drug ingredients. Singulair should be used with caution in patients with mild and moderate liver diseases. The use of Singulair in patients with severe liver diseases is not recommended.

Make sure to consult your health care provider if you are pregnant and breastfeeding. The treatment with Singulair should be carried only by a health care provider supervision.  

Special cautions

SINGULAIR tablets are not recommended for the treatment of acute asthma attacks. The dose of  inhaled glucocorticosteroids used in conjunction with SINGULAIR can be gradually lowered under medical supervision. The treatment with corticosteroids should not be rapidly replaced on generic Singulair. In those patients who used a combined therapy of Singulair there were reported the following Generic Singulair side effects:  eosinophilia, vascular rash, worsening of pulmonary symptoms, cardiac complications and / or neuropathy.  Although the causal relationship of theses adverse effects with combined therapy of generic Singulair with glucocorticosteroids was not studied properly.  

Administration

Generic Singulair is indicated only by a health care provider. Do not take Singulair generic without medical approval. For the treatment of bronchial asthma in adults the recommended dose is one tablet once daily. The dose is prescribed individually. Patients suffering from bronchial asthma and allergic rhinitis should take one tablet of generic Singulair once daily.

Side effects

In general generic Singulair is well tolerated. Generic Singulair side effects are mild or moderate and do not require the cessation of therapy. During the clinical trials there were observed the following Singulair side effects: reactions of hypersensitivity, erythremia, nightmares, skin rash, hives, Quince's edema, hallucinations, drowsiness, fatigability, anxiety, hyperirritability, suicidal thoughts, insomnia, paresthesia. In very rare cases: seaizures, nausea, diarrhea, stomach pain, headache, arthralgia, myalgia, tendency to bleedings, increased heart rate, edemas.

Drug interaction

SINGULAIR may be administered together with other drugs, traditionally used for prevention and long-term treatment of bronchial asthma. The recommended clinical dose of montelukast did not caused clinically significant effect on the pharmacokinetics of the following drugs: theophylline, prednisone, prednisolone, oral contraceptives (ethinyl estradiol / norethindrone), terfenadine, digoxin and warfarin.

AUC was decreased in patients while receiving phenobarbital (approximately 40%), but the correction of dosing regimen of generic SINGULAIR in such patients is not required.

Treatment with bronchodilators: SINGULAIR can be taken in patients which do not react to other  medicines used for bronchial asthma. Generic Singulair enhances the effect of inhaled corticosteroids and can be used in combination with them. The application of Singulair with inhaled corticosteroids allows reducing the dose of corticosteroids.

Singulair should not be taken when you receive the therapy with certain seizures medications. These drugs may decrease the blood levels of montelukast in the blood making the medicines ineffective. The list of anticonvulsants includes carbamazepine, primidine, Phenobarbital, phenytoin, fosphenytoin, pentobarbital and others