Treatment for asthma includes medications belonging to the category of leukotriene receptor antagonist, with Montelukast being one of the most frequently recommended medications. The drug is typically a part of treatment regimen and is recommended to pre-empt bronchoconstriction classified as exercise induced type. In addition to this, the drug is also used in the treatment of allergic rhinitis.  Following sub-sections offer a detailed look at the medication including montelukast mechanism of action to help users understand how the drug works. This will also help users and caregivers avoid any potential side effects of montelukast, or contraindications of montelukast, by learning more about its properties.

Overview of the leukotriene receptor antagonist

Before heading into the mechanism of action of the drug, here is a quick overview of the medication. In use since approval more than two decades ago, the medication is essentially a part of treatment regimen, and was primarily used as a supportive drug, despite its proven efficacy.  It was prescribed along with inhaled corticosteroids and other asthma treatment drugs. Certain effects were linked to the drug, and this was the basis for FDA assessment. While the effects are still linked to the drug, it is still a frequently prescribed medication.

How Montelukast works?

The drug is known to inhibit bronchoconstriction by selectively affinity to cysteinyl leukotriene receptor type-1. This results in preventing bronchoconstriction even with low doses.  The onset of action of the medication is known to occur quickly, with the mechanism of action delivering results two hours from the time of administration. This is also known to be part of the overall effects of combined used of prescription medications.  The medication is also known to have additional effects, by reducing peripheral blood eosinophils and this is also known to have a certain effect on the patients.

Here is an in-depth look at Montelukast mechanism of action. The mast cells and eosinophils release cysteinyl leukotrienes. And these in turn, bind to type-1 receptors on the smooth muscle cells of the respiratory airway, and in other cells that are known to induce inflammation. This stimulates the cells and causes the symptoms linked to asthma and allergic rhinitis.  Effects that are commonly experienced as an outcome of this binding include bronchoconstriction, mucous secretion, congested nasal passages.  Montelukast works by selectively binding with the receptors and preventing the binding of the cysteinyl leukotrienes with the receptors. This in turn inhibits the inflammatory actions of the cells, and prevents symptoms and conditions linked to asthma and allergic rhinitis.

Though the medication, through the mechanism of action outlined above, is known to be effective, it is still prescribed as a part of treatment regimen that includes inhaled corticosteroids.  Studies have demonstrated that Montelukast brings about a reduction in eosinophilic inflammation in the airway, and this makes it useful in treating chronic asthma in patients.

How the drug moves in the body and is absorbed?

With the information about the mechanism of action of the drug behind us, it is time to look at the manner in which the drug is absorbed in the body. Administered orally, Montelukast is absorbed in a manner so as to end up with peak plasma concentration anywhere between three to four hours, along with bioavailability above 60 percent.  The medication binds to plasma proteins, and is metabolized mainly by the liver, while the drug is flushed out by bile.

What is the best time of day to take Montelukast and how to take the drug?

The medicine can be taken with food or without food, though tests and results almost always refer to intake without food. One of the highlights of Montelukast is that whenever it is taken along with other medications intended to treat the same condition, the dosage need not be altered or reduced.  Ideally, the medication is recommended to be taken in the evening by patients diagnosed with chronic asthma. The recommended dosages for patients above the age of 15 are 10 mg per day. The dosage reduces to 5 mg per day when prescribed for patients between the ages of six and fourteen. Patients between the ages of one year to five years are administered 4 mg per day. It is not recommended for use in patients below the age of one.

The recommended dose of the medicine is to be taken once daily, and patients are to ensure that there is a clear gap of 24 hours between doses. There should be no effort to make up for missed doses by taking a double dose. The best option in the event of a missed dose is to skip it entirely and continue the schedule. The medication, when prescribed as a prophylactic to pre-empt bronchoconstriction as a result of exercise, is to be taken about 120 mins prior to workouts, separated by at least 24 hours. A regular intake of Montelukast for the treatment of chronic asthma does not prevent exercise-induced bronchoconstriction.

When prescribed for patients with allergic rhinitis, Montelukast may be taken either in the mornings or in the evenings. The prescribed or recommended doses for this condition are more or less the same as that of doses for asthma.  The drug is available in tablet form and as granules, with the tablets typically recommended for patients above the age of two or three years. The granules are generally recommended for patients below the age of two or three.

Modified montelukast dosage for asthma or other conditions

Most medications are often prescribed to be taken with altered dosages when the patient is diagnosed with certain conditions. This depends on the condition and the medication and is not applied as a generic formula across all drugs. Here is a look at some of the dosage alterations required/not required for Montelukast when treating patients with other pre-existing conditions. Individuals diagnosed with mild or moderate liver conditions are not required to opt for a change in dosage. However, when individuals are diagnosed with severe liver conditions, it may be necessary to seek medical advice regarding the appropriate dosage.

Patients with kidney ailments may also safely continue with the same dosage as this is not known to cause any impact. This is mainly be cause of the excretion of the medication through bile. However, as a precaution, individuals with severe kidney ailments or conditions are to seek medical advice about dosage. The drug is considered as relatively safe for pregnant women, as documented studies have not indicated any impact on the fetus. The medication is not known or linked to congenital disabilities as a result of use by pregnant mothers. Similarly, breast feeding mothers may also safely take the medication without any apprehensions of impact on the suckling child. This is mainly because the possible amounts of the medication that are likely to be ingested by infants are relatively less, and are not known to have any impact.

What are the possible side effects of Montelukast?

As outlined earlier, the drug was the subject of assessment by the FDA to look into possible adverse effects. These effects include reported neuropsychiatric events among patients on the medication. These effects have been reported across age groups, namely, adult patients, and youngsters on the drug. The effects that have been commonly reported include possible feelings of anxiety, bouts of depression, apart from an abnormally aggressive behavior. The patient may appear agitated at times, and may also experience issues with memory retention and inability to be attentive. In addition to this, the patient may also experience sleeping disorders and may end up with possible seizures. Suicidal tendencies also cannot be ruled out among patients on the medication, though this is not exclusively a reason or event as a result of Montelukast alone, and could be an amplifying factor.

Adverse effects of the drug include eosinophilia, throbbing headache, low- or high-grade fever, apart from overall fatigue. The patient is also likely to experience effects in the upper respiratory tract, such as sinusitis, pharyngitis or laryngitis. Another condition that may be experienced includes otitis. In addition to this, the patient may also experience issues with the lower respiratory tract such as cough and pneumonia, apart from possible wheezing.

Effects that are attributed to the drug include impact on the gastrointestinal tract such as feelings of nausea, bouts of diarrhea, and possible vomiting sensations. The patient is also likely to experience pain in the abdomen, apart from pancreatitis.  The individual is also likely to end up with infections such as the flu and infections from the varicella virus. The effects of the medication are also known to extend to the skin, such as possible pruritus, apart from eczema and atopic dermatitis. Other conditions that are also attributed to the drug include urticaria, outbreak of rashes on the skin, and frequent bruising.

In addition to the above effects, the individual is also likely to experience other conditions that are medically labelled as hypersensitivity related manifestations. This includes possible anaphylaxis, in addition to complications in the liver due to eosinophils.

Drug interactions of Montelukast

All medications come with the possibility of drug interactions and Montelukast is no exception. This occurs when two or more medications are taken together, ending up in a conflict of the mechanisms of action. This could also be the result of the properties of the constituents of the drugs. Patients on medications to treat hypersensitivity are likely to experience drug interaction related effects. Similarly, patients diagnosed with phenylketonuria are likely to experience effects due to the interaction between phenylalanine in medications and Montelukast. It is therefore necessary to exercise caution and avoid these interactions by replacing either of the two medications, depending on the importance of each.

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