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Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Diphenhydramine is an ethanolamine first-generation histamine H1 receptor antagonist with anti-allergic, antiemetic, antitussive, antimuscarinic and sedative effects. As an over-the-counter (OTC) medication, diphenhydramine is typically formulated as tablets and creams indicated for use in treating sneezing, runny nose, itchy/watery eyes, itching of nose or throat, insomnia, pruritus, urticaria, insect bites/stings, allergic rashes, and nausea. It may apparently also be used as an antiparkinsonian agent. In pharmaceutical products, both diphenhydramine base and – far more often – diphenhydramine hydrochloride (CAS number 147-24-0, EC number 205-687-2, molecular formula C17H22ClNO) may be employed, and possibly - rarely - diphenhydramine citrate or methylbromide (1).
Whence the Drugs?
Published in Mickey C. Smith, E.M. (Mick) Kolassa, Walter Steven Pray, Government, Big Pharma, and the People, 2020
Mickey C. Smith, E.M. (Mick) Kolassa, Walter Steven Pray
Sometimes side effects can have positive results. Diphenhydramine (Benadryl) can cause drowsiness. That’s the reason so many other antihistamines can label themselves “non-drowsy”. This one was easy. Who wants to be drowsy? People who have trouble sleeping! Check the ingredients on your OTC sleep remedy. You’ll find it listed.
Recognition, treatment, and prevention of systemic allergic reactions and anaphylaxis *
Published in Richard F. Lockey, Dennis K. Ledford, Allergens and Allergen Immunotherapy, 2020
Emma Westermann-Clark, Stephen F. Kemp, Richard D. deShazo
The standard treatment of anaphylaxis usually includes H1 antihistamines and corticosteroids. However, antihistamines have a much slower onset of action than epinephrine, they exert minimal effect on blood pressure, and they should not be administered as treatment alone [2]. Even at maximum dosages, antihistamines cannot abort anaphylaxis if histamine already occupies its receptor. They do, however, attenuate cutaneous symptoms, such as urticaria or generalized pruritus, and they may help prevent recurrence. For example, diphenhydramine, 25–50 mg for adults and 12.5–25 mg for children, may be administered intravenously once the cardiovascular and respiratory conditions are stabilized by epinephrine and/or fluids. IV administration ensures effective dosing will not be impaired by hemodynamic compromise, which adversely affects gastrointestinal or IM absorption, but maximal effect may not be observed for 1 hour [135]. Oral or IM administration of antihistamines may suffice for milder anaphylaxis, but we recommend epinephrine first for all cases. A systemic review was unable to make any evidence-based recommendations for the use of H1 antihistamines in the treatment of anaphylaxis [108].
Chitosan-coated alginate (CCA) nanoparticles for augmentation of topical antihistaminic activity of diphenhydramine: in-vitro optimization, skin histopathology and pharmacodynamic studies with in vitro/in vivo correlation
Published in Drug Development and Industrial Pharmacy, 2023
Sandy N. Aziz, Alia A. Badawy, Demiana I. Nessem, Nevine S. Abd El Malak, Marianne J. Naguib
Type I hypersensitivity, also known as acute hypersensitivity, is caused by antibodies called immunoglobulin E (IgE) attaching to the surface of mast cells [1,2]. When these antibodies come into contact with antigen, they activate mast cells, causing them to degranulate quickly, releasing histamine, serotonin, and other inflammatory mediators [3,4]. These mediators lead to a series of responses that is characteristic of allergy [5]. Depending on the site of release of histamine, different reactions are noticed, for example, histamine release in the skin causes hallmark wheals and flares [6,7]. There are different types of antihistamines used to treat hypersensitivity reactions, among them, H1-antihistamines are considered the first generation of antihistaminics and the prototype of H1-antihistamines is diphenhydramine hydrochloride (DHH) [8]. Diphenhydramine hydrochloride is a lipophilic drug [9] with a pKa value of 8.98 [10] thus easily crossing the blood–brain barrier when taken orally causing decrements in alertness and performance [11]. A conventional topical gel of diphenhydramine hydrochloride was used to avoid the oral side effects to treat skin allergy. However, multiple applications of gels to reach the best therapeutic effect lead to less patient compliance [12]. In addition, the topical diphenhydramine preparations demonstrated a very low antipruritic activity [13,14].
Efficacy of lipid emulsion therapy in treating cardiotoxicity from diphenhydramine ingestion: a review and analysis of case reports
Published in Clinical Toxicology, 2022
Joseph Clemons, Arvinder Jandu, Brandon Stein, Michael Chary
Diphenhydramine (DPH) is an inverse agonist at H1 histamine receptors and an antagonist at muscarinic receptors [1]. It is sold as an over-the-counter medication for allergic symptoms and as a sleep aid. A parenteral formulation, diphenhydramine hydrochloride, is commonly used as part of the treatment for severe allergic reactions and anaphylaxis. The oral and parenteral formulations can treat extrapyramidal symptoms and dystonic reactions. Diphenhydramine is also used for anxiolysis, sedation, euphoria, and hallucinations. Of the 2,595,526 exposures reported to US Poison Control Centers in 2016, 108,777 (4.19%) involved antihistamines and 75,833 (3.98%) involved only antihistamines; 30 of the 711 (4.2%) of the fatalities were judged likely or undoubtedly due to diphenhydramine ingestion [2].
A case of fatal paralytic shellfish poisoning in Alaska
Published in Clinical Toxicology, 2022
Courtney Temple, Adrienne Hughes
A 62-year-old woman from a small village in Unalaska, Alaska presented to a local clinic four hours after ingesting self-harvested Blue Mussels (M. Edulis) and Dogwinkle Snails (Nucella sp.). Initial symptoms included vomiting, perioral paresthesias and generalized weakness. Vital signs included a blood pressure of 220/160 mmHg, and a heart rate of 140 beats per minute without hypoxia or respiratory distress. Diphenhydramine and methylprednisolone were given for presumptive allergic reaction without improvement. The Oregon/Alaska Poison Center recommended immediate evacuation and early intubation for prolonged air transport 1200 miles inland. Symptoms progressed to facial numbness, worsening extremity weakness and altered mental status. During transport, she developed hypotension and sustained six cardiac arrests, was intubated and was placed on an epinephrine drip. She expired 12 h post-ingestion shortly after she arrived at the tertiary hospital. Meal specimens including snails and mussels in the cooking sauce were analysed by the Alaska State Environmental Health Laboratory. The mussels and snail specimens were significant for total SXT and congener concentrations of 11,200 mcg/100 mg and 287 mcg/100 mg respectively (Tables 1 and 2).