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Psychotropic Use during Pregnancy
Published in “Bert” Bertis Britt Little, Drugs and Pregnancy, 2022
Hydroxyzine is a piperazine antihistaminic compound that is used to treat anxiety, pruritus, nausea, and vomiting. The frequency of congenital anomalies in a double-blind controlled study was not increased among 74 newborns exposed in utero to hydroxyzine (50 mg/day) during the first trimester (Erez et al., 1971). Birth defects were not increased in frequency among 50 infants born to women who used hydroxyzine during the first trimester (Heinonen et al., 1977). Hydroxyzine has been shown to be a teratogen in rats (Giurgea and Puigdevall, 1968; King and Howell, 1966).
Infestations and Bites
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Topical treatments are applied to all areas of skin from the neck downward and left on as per instruction before washing off. Taking a hot bath before the application of lotion will facilitate drug delivery if the patient only bathes infrequently. Repeating the treatment after 7–10 days can ensure eradication of mites that have newly hatched. Oral antihistamines, such as hydroxyzine 25 mg every 6–8 hours, may be used to reduce intense itching.
Intrahepatic Cholestasis of Pregnancy
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Hydroxyzine. Hydroxyzine antagonizes central and peripheral histamine-1 receptors. Safety: FDA pregnancy category C; dose: 25–100 mg as needed every 6 hours orally. Hydroxyzine might improve tolerance to persistent itching, but this is not based on RCT data [21]. Antihistamines may provide some sedation at night but do not have a significant impact on pruritus.
An international Delphi study on the burden of allergic rhinoconjunctivitis and urticaria and the role of bilastine among current treatment options
Published in Expert Review of Clinical Immunology, 2023
MK Church, GW Canonica, P Kuna, M Maurer, R Mösges, Z Novak, NG Papadopoulos, P Rodriguez del Rio
The fact that some, albeit few experts were undecided on this statement may reflect that most clinicians, who manage allergic rhinitis and urticaria, do not assess sleep stages in their patients and therefore cannot be certain that impairing effects of first-generation antihistamines are due to specific effects on sleep. On the other hand, there is still a widespread belief that sleep is aided by adding a sedating first-generation H1-antihistamine, as hydroxyzine, at night, although this is not supported by available data [47]. Moreover, with a terminal half-life of 20–25 h [48], hydroxyzine has hangover effects into the next day, with a negative impact on overall performance [47]. Similarly, the first-generation antihistamine chlorpheniramine has shown to cause a significant worsening of next day cognitive functioning and psychomotor performance, whereas a single nocturnal dose of fexofenadine has advantages over chlorpheniramine, demonstrating to be free of disruption of nighttime sleep and detrimental effects on cognitive performance the next day [49]. Further information on the effects of antihistamines on sleep and sensory-motor performance may be a good target for further analysis.
Comment on: Are antimuscarinic effects common in hydroxyzine overdose? A cohort analysis of antimuscarinic effects in hydroxyzine and diphenhydramine poisoned patient
Published in Clinical Toxicology, 2023
Samantha S. Klein, Joshua Bloom, Marlis Gnirke, Mary Ann Howland
As the authors point out, diphenhydramine has more potent antimuscarinic activity and has resulted in significant morbidity, critical care admissions, and mortality in the USA when compared to hydroxyzine. This medication is available without a prescription and can easily be obtained in large bottles of hundreds of pills for self-harm or misuse [2,3]. Patients who overdose on hydroxyzine, as the authors point out, typically have more favorable outcomes. The most common manifestation of toxicity is central nervous system depression without other sequelae seen in diphenhydramine overdose, such as antimuscarinic toxicity, seizures, or ventricular dysrhythmias from sodium channel blockade. Interestingly, hydroxyzine is only available by prescription and thus is less accessible than diphenhydramine. Lack of access to large doses may have driven the results observed by the authors, and reporting the range of diphenhydramine recorded doses would have been useful in this regard.
Are antimuscarinic effects common in hydroxyzine overdose? A cohort analysis of antimuscarinic effects in hydroxyzine and diphenhydramine-poisoned patients
Published in Clinical Toxicology, 2023
The prevalence of sedation and CNS depression in hydroxyzine-poisoned patients is consistent with the inverse agonism of hydroxazine at the histamine H1 receptor [10–12]. Histamine H1 receptors modulate a multitude of physiologic functions, including the neuronal role of histamine in stimulating wakefulness and neurocognition [13]. The inhibition of Hydroxyzine at the H1 histamine receptor (Ki = 4.7–19 nM [14,15]) is three orders of magnitude greater than its inhibition of human muscarinic receptors. At a physiologic pH, hydroxyzine is an uncharged molecule, which allows it to readily cross the blood-brain barrier. When in the CNS, hydroxyzine can inhibit histamine-modulated neuronal transmission [16]. Two separate studies displayed that even therapeutic doses of oral hydroxyzine led to histamine H1 receptor occupancy of 67.6% and 53.95% in the brain [17,18]. Studies using positron emission tomography and mice with histamine-related gene knockouts have demonstrated that inhibition of histamine H1 receptors leads to decreased wakefulness and CNS depression [13]. This mechanism supports why sedation and CNS depression were seen commonly in hydroxyzine-poisoned patients. Hydroxyzine is also a weak potency antagonist at the serotonin 5-HT2, dopamine D2, and α1-adrenergic receptors [16].