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Paper 2
Published in Aalia Khan, Ramsey Jabbour, Almas Rehman, nMRCGP Applied Knowledge Test Study Guide, 2021
Aalia Khan, Ramsey Jabbour, Almas Rehman
Permethrin 5% needs to be applied over the whole body and left for 8–12 hours before it is washed off. Malathion should be applied for 24 hours. Both are re-applied after a week. The whole household should be treated. The itch may benefit from a sedating antihistamine, e.g. chlorphenamine.
Common/useful drugs
Published in Jonathan P Rogers, Cheryl CY Leung, Timothy RJ Nicholson, Pocket Prescriber Psychiatry, 2019
Jonathan P Rogers, Cheryl CY Leung, Timothy RJ Nicholson
CI/Caution/SE/Warn: as chlorphenamine, but also avoid in severe HF* (may undo haemodynamic benefits of opioids). Antimuscarinic fx (see p. 346, refer ‘Cholinoceptors’ in ‘Side Effect Profiles’ in ‘Basic Psychopharmacology’ chapter) are most prominent SEs.
Information on level of drugs into breastmilk
Published in Wendy Jones, Breastfeeding and Medication, 2018
Promethazine is widely used to reduce nausea particularly associated with travel sickness as well as symptomatic relief of urticaria and as an over-the-counter (OTC) hypnotic for short-term use. No data are available on transfer into breastmilk but it is believed that it does pass into breastmilk. It is licenced for use in children over 2 years. Chlorpheniramine is probably a safer option as a sedating anti-histamine for a breastfeeding mother unless there are compelling reasons to use promethazine. The BNF states that significant amounts of some anti-histamines are present in breastmilk – although not known to be harmful, manufacturers advise avoiding use in mothers who are breastfeeding.
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.
Alginate-based matrix tablets for drug delivery
Published in Expert Opinion on Drug Delivery, 2023
Natalia Veronica, Paul Wan Sia Heng, Celine Valeria Liew
Modulation of drug release from alginate-based matrix tablets can also be achieved by using alginates of appropriate viscosity. The viscosity has been shown to affect alginate hydration, swelling and erosion of the alginate-based matrix tablets with consequential effects on the drug release [42,69]. The effect of alginate viscosity on the drug release was more significant in the basic medium and less apparent in the acidic medium. In pH 6.8, tablets produced from high viscosity grade alginate (Keltone® HVCR, 400 cps at 1%, w/w) had slower metronidazole release than tablets produced from low viscosity grade alginate (Keltone® LVCR, 35 cps at 1%, w/w) [29]. Similarly, slower chlorpheniramine release was observed in tablets produced from Manucol SS/LL (108 cps at 1%, w/w) as compared to tablets fabricated from Manucol LB (3 cps at 1%, w/w) [42]. The faster drug release from tablets produced from low viscosity grade alginates could be explained by the rapid disentanglement of the polymer upon hydration [42]. Accordingly, the tablet matrices are more prone to erosion, producing a shorter diffusion path length for the drug molecules and facilitating drug release from the tablets produced using low viscosity grade alginates. Extensive swelling of high viscosity grade alginate (14,000 cps at 2%, w/w) in pH 6.8 has also been suggested to slow down theophylline release compared to low viscosity grade alginate (250 cps at 2%, w/w) [69]. The extensively swollen tablet matrices considerably increased the drug diffusion pathway.
Association of H1-antihistamines with torsade de pointes: a pharmacovigilance study of the food and drug administration adverse event reporting system
Published in Expert Opinion on Drug Safety, 2021
Zahid Ali, Mohammad Ismail, Fahadullah Khan, Hira Sajid
There also exist mixed reports in the literature regarding the association of loratadine with QTIP and TdP, one study reported the possibility that loratadine when dosed higher than the therapeutic one can cause 40% blockade of potassium channel thus causing QTIP and subsequent TdP [31]. One study reported the association of loratadine with TdP mainly due to drug-interactions (especially with amiodarone) and enzyme inhibitors [29]. In our study loratadine was associated with the highest number of QTIP cases, cardiac reactions, electrolyte abnormalities, drug–drug interactions, and overdose cases among new signals (Table 5). Literature also supports the association of chlorpheniramine with QTIP and TdP [32]. Chlorpheniramine can increase the duration of action potential and induce QT prolongation by blocking the hERG channel as evident from studies [33,34]. One study concluded that chlorpheniramine can induce cardiac toxicity when used in higher doses [10].