Montelukast
Risk Factor: BM
Class: RESPIRATORY DRUGS
/ Leukotriene Receptor Antagonists
Contents of this page:
Fetal Risk Summary
Breast Feeding Summary
References
Questions and Answers
Fetal Risk Summary
Montelukast, an oral inhibitor of the cysteinyl leukotriene CysLT1 receptor, is indicated for the prophylaxis and chronic treatment of asthma. Reproduction studies in rats and rabbits at doses up to 320 and 490 times the maximum recommended human daily oral dose (MRHOD) based on body surface area, respectively, found no evidence of teratogenicity (1). The drug impaired the fertility of female rats at 160 times, but not at 80 times, the MRHOD. Fertility in male rats was not affected by oral doses up to 650 times the MRHOD (1).
It is not known if montelukast crosses the human placenta. The molecular weight (about 608) is low enough, however, that transfer to the fetus should be expected. The drug crosses the placenta in rats and rabbits (1).
The manufacturer maintains a pregnancy registry for montelukast (2). As of May 2000, there were 66 prospective (reported before outcome of pregnancy known) reports of exposure during gestation. Of these, 36 of the pregnancy outcomes were pending, and 12 were lost to follow-up. Of the 18 remaining pregnancies, 14 were exposed in the 1st trimester, 1 was exposed in the 2nd trimester, 1 in the 3rd trimester, and the timing of two exposures was unknown. There were no pregnancy complications and all delivered healthy infants without congenital anomalies or newborn complications. Two of the liveborn infants were premature, 35 and 36 weeks', respectively.
In six retrospective cases (received after pregnancy outcome was known), two terminated in spontaneous abortions at gestational weeks 8 and 5 or 6, respectively (2). No information on the embryos was available. Three normal liveborn infants were reported, one of whom had low birth weight. In another case, the mother died at 7 months' gestation from severe asthma exacerbation but whether the fetus survived was not known. She had used montelukast for 4 weeks in the 2nd trimester.
During clinical trials, 38 women received montelukast with or without standard asthma therapy (b-adrenergic agents, corticosteroids, theophylline, and/or cromolyn sodium) (2). In all cases, montelukast treatment was limited to the 1st trimester. The outcome of three pregnancies was pending or lost to follow-up. The pregnancy of one woman, who was also receiving loratadine, an antihistamine, terminated in a 1st-trimester spontaneous abortion. In another, the report could not determine if her abortion was spontaneous or elective. Seven other women had spontaneous abortions in the 1st trimester, and nine pregnancies were electively terminated (none for identified medical indications). One fetal death at 2830 weeks' gestation was attributed to preeclampsia, intraventricular cranial hemorrhage, immaturity, and placental infarcts (2). No congenital malformations were observed in the fetus by macroscopic analysis. Healthy, full-term infants were delivered from the remaining 16 pregnancies. No differences in the pregnancy outcomes were observed between the montelukast group and those who received placebo or beclomethasone (2).
In summary, montelukast is not teratogenic in animals, and there have been no reports of adverse pregnancy outcomes attributable to the drug in humans. However, the human data are very limited and lack sufficient power to detect an increased risk of congenital malformations or other adverse outcomes. One source states that montelukast may be safe to use during pregnancy, but this conclusion was based solely on animal studies (3). Health care providers are encouraged to report any prenatal exposure to montelukast to the Merck Pregnancy Registry for Singulair at (800) 986-8999.
Breast Feeding Summary
No reports describing the use of montelukast during human lactation have been located. The molecular weight (about 608) is low enough, however, that excretion into breast milk should be expected. The drug is excreted into the milk of lactating rats (1). The potential effects on a nursing infant from exposure to the drug in milk are unknown.
References
- Product information. Singulair. Merck, 2000.
- Merck Pregnancy Registry for Singulair (montelukast sodium). Second annual report on exposure during pregnancy covering the period from approval through May 20, 2000. October, 2000.
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Anonymous. Drugs for asthma. Med Lett Drugs Ther 2000;42:1924.
Questions and Answers
Validated HPLC analysis of montelukast and levocetrizine in pharmaceutical formulation and bilogical sample.?, Montelukast is a leukotriene inhibitor used to prevent asthma attacks in adults and children as young as 12 months old. Levocetirizine, a third generation non-sedative antihistamine is also used along with Montelukast in persistent allergic asthma. The combination of these two can be determined in pharmaceutical formulations and biologiacal samples using HPLC analysis method.
Great!
Why is it important that Singulair (montelukast Na) be in ionized form at the pH of blood?, Please provide a reputable source and explanation please!
Large organic molecules tend to be insoluble in water (like dissolves like). For this molecule to be soluble, you must try to make it as hydrophilic (i.e. water loving) as possible. This is usually accomplished by using an sodium, or potassium salt, or in other molecules, by acidifying or alkalinizing the drug.
In short, if it wasn't a salt, it would not be soluble enough in the plasma (which is mostly water) and could not circulate to the target regions.
Damn, you went and acutally made me use my organic chem knowledge. :-)
3yr daughter suffered with asthma for the last 2yrs has been given various inhalers and montelukast tablets?, Daughter has been on seratide all summer with no symptoms however the start of this month her symptoms have come back just the same so dont understand what is the point of taking the inhaler if the symptoms still appear in the winter just the same?
does she take her meds as prescribed? MONTELUKAST (Singulair®) helps to reduce asthma symptoms (coughing, wheezing, shortness of breath, or chest tightness) and control your asthma. It does not provide instant relief and cannot be used to treat a sudden asthma attack. It works only when used on a regular basis to help reduce inflammation and prevent asthma attacks. Montelukast is effective in adults and children. This drug is also helpful in improving seasonal allergies, like hay fever. Generic montelukast tablets or chewable tablets are not yet available. she should have something like an Albuterol inhaler too and a rescue inhaler for emergencies. decadron is a steriod that helps too. cold weather exacerbates asthma as does ragweed that is produced this time of year. even with drugs and inhalers, she'll have "episodes". most hold asthma at bay but she can have break through episodes. talk to your doctor about it and see if he can make any suggestions or med changes. kids change so quickly that meds that worked one month can have no effect the next since their body chemstries change so rapidily. the good news is that the chance of her growing out of it are excellent since she's so young.
My doctor prescribed me "montelukast" but the pharmacist dispensed "montelukast sodium". Are these 2 thesame?, Should I return the montelukast sodium to the drugstore or is it okay I just use it?
Montelukast (Brand name Singulair) is used for the treatment of asthma. It works by stabilizing the mast cells which are thought to be the major products in the causing of inflammation and constriction of the airways.
Montelukast is the active ingredient and sodium is the "salt" that it is attached to. The reason for binding it to the sodium is for the purpose of allowing the drug to easily penetrate the cell, thus, producing a better effect.
Most drugs are bound to "salts" such as sodium and potassium. Both these have good penetrative properties.
In short, the drug you have been dispensed it correct.
The Pharmacist.
What happens if you double dose on Singulair (Montelukast)? It says DO NOT TAKE MORE THEN 1 IN 24 HOURS.?, How dangerous is it? The dosage is 10mg. This was several days ago so I probably only took one, but what happens if I or someone DOES take 20 mg of Singulair when prescribed 10mg? What would happen?
The danger is none to slim ... most overdoses that have been documented exceeded 1000 mg ... so .. 20 mg will probably show little effect or may enhance the side effects that you feel .. if you have any ....
Can Montelukast be given in skin allergies?,
Like to treat skin allergies? No. It is for allergic rhinitis or asthma.
Why montelukast must taken in the evening?,
Singulair (Montelukast) should be taken in the evenings because one of it's major side effects is fatigue. It's much easier to deal with at night when you're about to go to bed anyway, rather than trying to battle it during the day.
Also, the bronchodilation effects (opening of the airways) prevents asthma attacks and helps promote a more restful sleep, because you can breathe easier.
What happens if I accidentally double dosed on Singulair (Montelukast)? 10mg?, I'm worried something is going to happen. I don't think I did, I'm not usually forgetful... but just in case.
You will be fine. Just try not to do it.
why montelukast is recomended at night for asthma and at morning for allergic rhinitis?,
singulair is recommended at night for asthma because during the clinical trial and other studies for singulair, it was noted that the night time dosing decreased the number of wakening due to asthma symptoms ( coughing, wheezing). it is recommended during the morning because it inhibits the release of substances in the body that are released when we come into contact with the particular allergen. therefore you will have protection against the allgeric reaction for the full day.
