Histamine mediates most of its effects on airway function via H1-receptors. Non-sedating potent H1 -receptor antagonists, such as terfenadine, fexafenadine, loratadine, Clarinex-D , ebastine, and astemizole, have useful clinical effects in allergic rhinitis, but they are far from effective in asthmatic patients . The effects of anti-histamines are small and clinically insignificant. Terfenadine causes about 50% inhibition of the immediate response to allergen, but has no effect on the late response . Anti-histamines cause a small degree of bronchodilatation in asthmatic patients, indicating a certain degree of histamine “tone,” presumably due to the basal release of histamine from activated mast cells . Chronic administration of terfenadine has a small clinical effect in mild allergic asthmatic patients, but is far less effective that other anti-asthma therapies. H1-receptor antagonists have not been found to be useful in more severe asthmatic patients . The new generation anti-histamines, cetirizine and astemizole, have some beneficial effects in asthma, that may be unrelated to their H1-antagonist effects .
H2-antagonists, such as cimetidine and ranitidine, may be contraindicated in asthma on theoretical grounds, if H2-receptors are important in counteracting the bronchoconstrictor effect of histamine. In clinical practice, however, there is no evidence that H2-antagonists have any deleterious effect in asthma. H3-receptor agonists may have some theoretical benefit in asthma, since they may modulate cholinergic bronchoconstriction and inhibit neurogenic inflammation. Although (R)-α-methylhistamine relaxes rodent peripheral airways in vitro, it has no effect when given by inhalation on airway caliber or metabisufite-induced bronchoconstriction in asthmatic patients, indicating that a useful clinical effect is unlikely .
Histamine H4-receptors are expressed on eosinophils, T- cells, dendritic cells, basophils and mast cells, mediate mast cell, eosinophil and dendritic cell chemotaxis, and modulate cytokine production from dendritic cells and T-cells, indicating that blockade of histamine H4-receptors may lead to anti-allergic and anti-inflammatory effects. Several histamine H4-receptor antagonists are now available but remain to be tested in allergic asthma or rhinitis . Antagonists that block both histamine H1- and H4-receptors may be an effective combination. Anti-histamines have a useful effect in the treatment of rhinitis, and particularly the rhinorrhea. As a large proportion of patients with asthma have concomitant rhinitis, an H1-antagonist may help the overall management of asthma . While H1-receptor antagonists alone may be ineffective, some studies suggest that they may have some efficacy in combination with other antagonists. Thus, an H1-receptor antagonist when added to an anti-leukotriene was able to inhibit the early and late responses to allergen more effectively than the anti-leukotriene alone , but as yet there has been no studies of combination mediator antagonists in asthma.
There is no evidence that anti-histamines have any role in the treatment of COPD.
Dosage Forms and Strengths
Clarinex-D tablets USP, 5 mg are light blue, circular, biconvex, film-coated tablets, debossed "LU" on one side and "S71" on other side.
What form(s) does this medication come in?
Each blue, round, coated tablet, debossed with a "D" on one side of the tablet, contains 5 mg Clarinex-D. Nonmedicinal ingredients: FD&C Blue No. 2 Aluminium Lake, hypromellose, lactose, magnesium oxide, microcrystalline cellulose, polythylene glycol, pregelatinized starch, titanium dioxide, and zinc stearate.
Generic Name: Clarinex-D Tablets (des lor AT a deen)Brand Name: Clarinex
Medically reviewed by Drugs.com. Last updated on Sep 10, 2019.
- Allergy warning: You shouldn’t use Clarinex-D if you’re allergic to it or any of its components. This drug can cause a hypersensitivity (allergic) reaction. This can lead to itching, rash, swelling, shortness of breath, and swelling of your lips, face, or tongue.
Clarinex-D is a prescription drug. It comes in three forms: tablet, disintegrating tablet, and oral syrup. You take all forms by mouth.
Clarinex-D is available as the brand-name drug Clarinex. It’s also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, they may not be available in every strength or form as the brand-name drug.
Animal Toxicology And/Or Pharmacology Reproductive Toxicology Studies
Clarinex-D was not teratogenic in rats at doses up to 48 mg/kg/day (estimated Clarinex-D and Clarinex-D metabolite exposures were approximately 210 times the AUC in humans at the recommended daily oral dose) or in rabbits at doses up to 60 mg/kg/day (estimated Clarinex-D exposures were approximately 230 times the AUC in humans at the recommended daily oral dose). In a separate study, an increase in pre-implantation loss and a decreased number of implantations and fetuses were noted in female rats at 24 mg/kg (estimated Clarinex-D and Clarinex-D metabolite exposures were approximately 120 times the AUC in humans at the recommended daily oral dose). Reduced body weight and slow righting reflex were reported in pups at doses of 9 mg/kg/day or greater (estimated Clarinex-D and Clarinex-D metabolite exposures were approximately 50 times or greater than the AUC in humans at the recommended daily oral dose). Clarinex-D had no effect on pup development at an oral dose of 3 mg/kg/day (estimated Clarinex-D and Clarinex-D metabolite exposures were approximately 7 times the AUC in humans at the recommended daily oral dose).
When taken with Clarinex-D, some antibiotics can increase the amount of Clarinex-D in your body. This can cause more side effects. Examples of these drugs include:
Clarinex-D passes into breast milk. There are not sufficient data on the effects of Clarinex-D on the breastfed infant or the effects of Clarinex-D on milk production. The decision should be made whether to discontinue nursing or to discontinue Clarinex-D, taking into account the developmental and health benefits of breastfeeding, the nursing mother's clinical need, and any potential adverse effects on the breastfed infant from Clarinex-D or from the underlying maternal condition.
Is Clarinex-D safe to take if I'm pregnant or breastfeeding?
Clarinex-D has not been studied in pregnant women.
Clarinex-D passes into breast milk and should therefore be used with caution in women who are breastfeeding.
It is not uncommon to see claims that some of the newer antihistamines are “non-sedating”. This is a misleading term; it is more correct to describe them as having minimal sedative effects when taken in their recommended doses. One problem is that most objective studies that support a so-called risk-free sedation profile for certain antihistamines are based on the use of non-allergic healthy volunteers (29 R ). The issue is further complicated by evidence that individuals with symptoms of allergic rhinitis have reduced vigilance, with decrements in speed and efficiency across several cognitive domains (30 C ).
It is therefore of interest that the nervous system effects of Clarinex-D have been assessed in subjects with ragweed-induced allergic rhinitis (aged 18–60 years) who had predetermined severity of symptoms after challenge with ragweed pollen in an Environmental Exposure Unit (31 C ). The subjects performed a comprehensive battery of repeatable, automated, neuropsychological tests before and 90 minutes after treatment with a randomized single dose of placebo, Clarinex-D 5 mg, or the positive control diphenhydramine 50 mg. Compared with placebo, both antihistamines alleviated the symptoms of rhinitis associated with exposure to ragweed pollen. As expected, diphenhydramine caused significant reductions in all vigilance parameters, while were no significant differences on any of the cognitive or subjective parameters between subjects treated with Clarinex-D and those given placebo.
In another more conventional study in nine healthy volunteers, the effect of deslorata-dine 5 mg on psychomotor performance, daytime sleep latencies, subjective sleepiness, and memory was assessed in a placebo-controlled, double-blind, crossover study, with promet-hazine 25 mg as a positive control (32 C ). The authors concluded that Clarinex-D has a favorable nervous system adverse effects profile and that it could prove suitable for allergic individuals who are involved in skilled activities, such as driving.
In multiple-dose placebo-controlled trials, 2834 patients ages 12 years or older received CLARINEX Tablets at doses of 2.5 mg to 20 mg daily, of whom 1655 patients received the recommended daily dose of 5 mg. In patients receiving 5 mg daily, the rate of adverse events was similar between CLARINEX and placebo-treated patients. The percent of patients who withdrew prematurely due to adverse events was 2.4% in the CLARINEX group and 2.6% in the placebo group. There were no serious adverse events in these trials in patients receiving Clarinex-D. All adverse events that were reported by greater than or equal to 2% of patients who received the recommended daily dose of CLARINEX Tablets (5 mg once daily), and that were more common with CLARINEX Tablets than placebo, are listed in Table 1.
Table 1: Incidence of Adverse Events Reported by ≥2% of Adult and Adolescent Allergic Rhinitis Patients Receiving CLARINEX Tablets
The frequency and magnitude of laboratory and electrocardiographic abnormalities were similar in CLARINEX and placebo-treated patients.
There were no differences in adverse events for subgroups of patients as defined by gender, age, or race.
In the event of overdose, consider standard measures to remove any unabsorbed drug. Symptomatic and supportive treatment is recommended. Clarinex-D and 3-hydroxyClarinex-D are not eliminated by hemodialysis.
Information regarding acute overdosage is limited to experience from post-marketing adverse event reports and from clinical trials conducted during the development of the Clarinex-D product. In a dose-ranging trial, at doses of 10 mg and 20 mg/day somnolence was reported.
In another study, no clinically relevant adverse events were reported in normal male and female volunteers who were given single daily doses of Clarinex-D 45 mg for 10 days .