Sedation, antihistamines and

The first-generation Hi antihistamines, also referred to as sedating antihistamines, and the second-generation antihistamines, the less or nonsedating antihistamines, are among the most frequently used oral medications for ocular allergies. Table 13-3 lists commonly used oral antihistamines and some of their important pharmacologic properties. 

Sedating antihistamines and hyoscine are licensed for use without prescription for prophylaxis and treatment of motion sickness. They appear to be of more or less equivalent efficacy. 

However, a few individuals exhibit drowsiness and other central nervous system side-effects in response to non-sedating antihistamines and even to placebo, and impairment of function, if it occurs, is not always accompanied by subjective feelings of drowsiness. Patients should therefore be warned that these antihistamines may affect driving and other skilled tasks and that excess alcohol should be avoided.)... 

The effect of various azole antifungals on the plasma levels of the non-sedating antihistamines, and their cardiac effects from controlled studies are summarised in Table 15.3 , (p.585). The subsections below include data from case reports and further studies. 

Sedating antihistamines and antipsychotics aren t addictive, but again prevent habituation, so can prolong problems or obstruct CBT. 

Many cough and decongestant preparations contain sedating antihistamines and sometimes non-sedating antihistamines. 

The nurse usually gives tiiese drug in die outpatient setting. If the patient is in the hospital or clinic, the nurse observes the patient for die expected effects of die antihistamine and for adverse reactions. The nurse reports adverse reactions to the primary health care provider. In some instances, drowsiness or sedation may occur. When the drug is given to relieve preoperative anxiety, these adverse reactions are expected and are allowed to occur. 

I Older adults are more likely to experience anticholinergic effects (eg, drynessofthe mouth, nose, and throat), dizziness sedation, hypotenson, and confusion from the antihistamines A dosage reduction may be necessary if these symptoms persist. 

Histamine H,-antagonists For intravenous infusion diphenhydramine, dimetindene and ciemastine are avaiiabie. There are no controiied studies for the new non-sedating antihistamines in the treatment of anaphyiaxis... 

FDA for chronic use up to 6 months.33 Although not first line-agents for insomnia, sedating antihistamines are prescribed commonly, and the number of prescriptions has increased dramatically over the last 20 years.34 These and other therapies, detailed below, are used to treat insomnia. 

Antihistamines such as diphenhydramine are known for their sedating properties and are frequently used over-the-counter medications (usual doses 25-50 mg) for difficulty sleeping. Diphenhydramine is approved by the FDA for the treatment of insomnia and can be effective at reducing sleep latency and increasing sleep time.43 However, diphenhydramine produces undesirable anticholinergic effects and carryover sedation that limit its use. As with TCAs and BZDRAs, diphenhydramine should be used with caution in the elderly. Valerian root is an herbal sleep remedy that has inconsistent effects on sleep but may reduce sleep latency and efficiency at commonly used doses of 400 to 900 mg valerian extract. Ramelteon, a new melatonin receptor agonist, is indicated for insomnia characterized by difficulty with sleep onset. The recommended dose is 8 mg at bedtime. Ramelteon is not a controlled substance and thus may be a viable option for patients with a history of substance abuse. 

Is the patient taking antihistamines and/or intranasal steroids Is the patient experiencing adverse effects (e.g., sedation from antihistamines or nasal itching, burning, or bleeding from intranasal corticosteroids) ... 

Bupropion should not be administered with sedating antihistamines because of the increased risk of seizures. Bupropion is used for smoking cessation therapy and may cause insomnia as a side-effect. Patients are advised to avoid taking bupropion dose at bedtime. 

Codeine, dextromethorphan and pholcodine are opioid cough suppressants indicated for dry cough. Sedating antihistamines, such as diphenhydramine, tend to have an antitussive action as well. Vitamin C is not used in the management of cough but may be used as a prophylaxis against colds. 

Carbocisteine is classified as a mucolytic as it reduces sputum viscosity and aids its elimination. Carbocisteine is therefore indicated for use in chesty cough. Pholcodine, dextromethorphan and the sedating antihistamines, such... 

Cetirizine is a non-sedating antihistamine drug that may be used for symptomatic relief in allergic rhinitis (hay fever) as it reduces rhinorrhoea and sneezing. Fexofenadine is an active metabolite of terfenadine (another antihistamine). 

Desloratadine is a non-sedating antihistamine. Diphenhydramine, chlor-phenamine, promethazine and alimemazine are sedating antihistamines with diphenhydramine and promethazine being marketed in over-the-counter hypnotic preparations. 

This drug is an antihistamine (see Section 9 for a detailed discussion) and helps alleviate the symptoms of seasonal allergies. It causes less sedation than most antihistamines and appears to be just as effective. The key step in a recent synthesis is a Wittig-type reaction. 

The treatment should be causal, but symptomatic treatment is also important. Heat and dehydration should be counteracted as far as possible. Skin softeners without perfume and irritant ingredients should be used frequently to treat dry skin. A sedating antihistamine often alleviates the pruritus, especially at night. Local steroids have no place in treatment unless there are inflammatory skin changes. 

It is usual to give a sedating antihistamine, for example chlorphenamine 10 mg by intramuscular or slow intravenous injection, because of the relatively short half-life of epinephrine (adrenaline), and because of the active role of histamine in anaphylaxis. In addition, the inflammatory reaction can be moderated by the administration of a corticosteroid, such as hydrocortisone 200 mg by intramuscular or slow intravenous injection. Corticosteroids may take several hours to act, but can be of some help in so-called biphasic anaphylactic reactions. 

Sedation is often seen in adults as a side effect of treatment. It is presumably related to a combination of anticholinergic, antihistaminic, and serotonergic effects of this medication. Sedation is seen more often with the tertiary amines than with the secondary amines (Baldessarini, 1996). 

The same molecules used to treat allergies and cold symptoms have many other uses. Antihistamines are particularly effective as antiemetics in suppressing nausea associated with gastrointestinal illnesses. They can also be used to treat the symptoms of motion sickness or even vestibular disturbances (vertigo). Because of their ability to induce sedation, antihistamines are widely used in over-the-counter sleep aids. 

Majority of antihistaminic drugs produce variable degree of CNS depression i.e. sedation, drowsiness and sleep. Drugs like diphenhydramine, promethazine are potent sedatives and is often accompanied by inability to concentrate. 

The newer antihistaminics agents e.g. Azelastme inhibits histamine release and also inflammatory reactions evoked by leukotrienes and plasma activating factor (PAF). It is used for seasonal and perennial allergic rhinitis in the form of nasal spray. Mizolastine, a non-sedating antihistaminic is used in allergic rhinitis and urticaria. Ebastine, another non-sedating antihistaminic is used in nasal and skin allergies. 

It is a cromolyn analogue. It is an antihistaminic (H antagonist) and probably inhibits airway inflammation induced by platelet activating factor (PAF) in primate. It is not a bronchodilator. It is used in asthma and symptomatic relief in atopic dermatitis, rhinitis, conjunctivitis and urticaria. It is absorbed orally and well tolerated. Bioavailability is 50% due to first pass metabolism and is primarily metabolized. The common side effects include dry mouth, sedation, dizziness and nausea. 

Sedation is common, particularly at initiation of treatment and is largely related to antihistamine and antiadrenergic effects. Weight gain may also be related to antihistamine effects. Some recent evidence suggests there can be impairment of psychomotor function but in the treatment of patients with depression this must... 

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