Antihistamines

10 Antihistamines


The term ‘antihistamine’ refers to H2 receptor antagonists and are subdivided into sedating antihistamines and non-sedating antihistamines. Uses include:



image Antiemetics for nausea and vomiting (see Chapter 8)


image Emergency treatment (anaphylactic shock)


image Allergy relief


image Cholestasis of pregnancy


image Premedication and sedation


image Insomnia


image Relief of colds and coughs.


Histamine is present in animal tissues and some release occurs after injury, but also after an allergic reaction, and gives rise to urticaria, asthma, hay fever and ultimately anaphylaxis. Antihistamines are palliative agents because they neither destroy nor prevent the release of histamine, but act by blocking access to histamine receptor sites and thereby inhibiting an allergic reaction. Antihistamines are usually thought of as being taken orally, but they can be injected; for example, chlorpheniramine and promazine are used as adjuncts to adrenaline (epinephrine) in the treatment of anaphylaxis (see Chapter 25). They can also be used intranasally, intraocularly and topically.


The student should be aware of:



image the physiology related to allergic response


image the most common factors causing allergic response


image recognition of and treatment for anaphylactic shock


image interactions of drug therapy that may produce an allergic response.



Midwives can administer ‘adrenaline 1:1000’ for anaphylaxis under the Midwives’ Exemptions (NMC, 2011).




BP

Chlorpheniramine maleate

Proprietary

Piriton® (GlaxoSmithKline Consumer Healthcare)
Chlorpheniramine maleate (non-proprietary, see BNF for details)

Group

Antihistamine – sedative

Uses/indications

Symptomatic control of all allergic conditions responsive to antihistamines, including hay fever, vasomotor rhinitis, urticaria, angioneurotic oedema, food allergy, drug and serum reactions, insect bites
Symptomatic relief of itch associated with chickenpox
anaphylaxis – see Chapter 25
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Jul 11, 2016 | Posted by in MIDWIFERY | Comments Off on Antihistamines

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