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H1-Antihistamines for Allergic Diseases: Old Aged but Not Old-Fashioned Drugs

H1-antihistamines were introduced for clinical use in 1942 and since then more than 45 H1-antihistamines have been available worldwide representing the largest class of medications used in the treatment of allergic diseases. H1-antihistamines are functionally classified into two groups: First generation and second generation antihistamines. The older, so-called first generation H1-antihistamines, such as Chlorpheniramine, Diphenydramine, Doxepin, Hydroxyzine after oral or parenteral administration are metabolized in the liver and excreted in large part with the urines. Pharmacological action occurs after 30-60 minutes and persists for about 4-6 hours. First generation antihistamines are characterized…

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Articles of Interest

Antihistamine Use in Cold Remedies Is Criticized

The antihistamines found in most cold remedies on the market may do more harm than good, medical experts said today, suggesting that they be removed from those products. One expert said a shot or two of whisky before sleeping might be better for a cold sufferer than a nip of cold medicine.

Comparative pharmacology of H1 antihistamines: clinical relevance

H1 antihistamines have similar efficacy in the treatment of allergic disorders; however, they differ in terms of their chemical structure, clinical pharmacology, and safety. This review focuses on the clinical pharmacology (pharmacokinetics and pharmacodynamics) of the newer oral H1 antihistamines (acrivastine, cetirizine, desloratadine, ebastine, fexofenadine, levocetirizine, loratadine, and mizolastine).

First-generation antihistamines in pediatric use

First-generation antihistamines have never been adequately studied for use in pediatric age groups in terms of efficacy and safety. Nevertheless, they are still used in an apparently high percentage of such patients.

First-Generation H1-Antihistamine Prescribing in Hospitalized Patients:

First-generation H1-antihistamines are commonly utilized in hospital, however, these agents are associated with a number of undesirable adverse effects such as central nervous system (CNS) depression, cardiotoxicity and death in overdose.

Goodbye, Benadryl: It is time for you to retire

Newer alternatives are more effective, act more quickly, and last longer.

H1 antihistamines and dementia risk in allergic rhinitis

The study found a dose-dependent increase in dementia risk among antihistamine users.

H1 Antihistamines: Current Status and Future Directions

First-generation H1 antihistamines cross the blood-brain barrier, and in usual doses, they potentially cause sedation and impair cognitive function and psychomotor performance. These medications, some of which have been in use for more than 6 decades, have never been optimally investigated. Second-generation H1 antihistamines such as cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine cross the blood-brain barrier to a significantly smaller extent than their predecessors.

Histamine and H1-antihistamines: Celebrating a century of progress

In this review we celebrate a century of progress since the initial description of the physiologic and pathologic roles of histamine and 70 years of progress since the introduction of H1-antihistamines for clinical use.

Over-the-counter H1-antihistamines

First-generation antihistamines bind nonselectively to central and peripheral inactive H1-receptors. They have various indications, including allergic rhinitis (hay fever), allergic conjunctivitis, urticaria/angioedema, vasomotor rhinitis, sneezing, asthma, and hypersensitivity reactions. The four first-generation oral agents available over-the-counter (OTC) can be further classified, based on their chemical composition, into two groups: alkylamines (chlorpheniramine) and ethanolamines (clemastine, diphenhydramine, and doxylamine). This latter group has marked sedative properties, as well as anticholinergic and antiemetic actions.

Review of H1 Antihistamines in the Treatment of Chronic Idiopathic Urticaria

The first antihistamine was developed in 1937; in the 1940s, phenbenzamine became the first commercially available antihistamine, followed by similar H1-receptor antagonists such as chlorpheniramine, brompheniramine, and diphenhydramine. Despite its relative antiquity, diphenhydramine remains the most widely used antihistamine in the United States.

Resources

Antihistamines List

Antihistamines are a class of agents that block histamine release from histamine-1 receptors and are mostly used to treat allergies or cold and flu symptoms, although some first-generation antihistamines may also be used for other conditions.