Antihistamines

ACTIONS

Competitively block the H₁-receptor sites and impede histamine-mediated responses. Second-generation antihistamines cause less drowsiness.

USES

• Prevent and treat seasonal allergies, decrease itching and pruritis.

• Are adjunct with epinephrine for severe allergic reaction (anaphylaxis).

• Prevent and treat motion sickness.

PRECAUTIONS

• Asthma—acute or chronic; chronic obstructive pulmonary disease (COPD)

• Pregnancy and lactation; glaucoma

• Conditions resulting in urinary retention and obstruction

SIDE EFFECTS

• Benadryl: Includes ^**sedation, thickening of bronchial secretions, dry mouth, drowsiness, dizziness,^** and muscular weakness.

• Second generation: Minimal side effects occur—drowsiness, dry mouth, constipation, urinary retention, and headache.

• Zyrtec: May cause paradoxical reaction in children—restlessness, anxiety.

NURSING IMPLICATIONS

1. ^‡Caution patient not to take antihistamines with alcohol.^‡

2. diphenhydramine (Benadryl)—^‡Caution patient about drowsiness because^‡ of safety concerns.

3. Do not administer antihistamines within 4 days of skin testing.

Bronchodilators

ACTIONS

Short-acting beta₂ agonists (SABA) are selective adrenergic agonists. Sympathomimetic agents activate the beta₂-receptors to relax the smooth muscles in the bronchioles, producing dilation.

USES

• Short-acting preparations to treat acute exacerbations of asthma

• Short-term relief of bronchoconstriction caused by bronchitis, emphysema, and asthma

• Prevention of exercise-induced bronchospasm (EIB)

SIDE EFFECTS

• ^**Headache, nausea, restlessness, nervousness, tremors^**

• Increased blood pressure (BP), heartburn, insomnia, bronchial irritation

ADVERSE OR TOXIC EFFECTS (Excessive sympathomimetic stimulation)

• Palpitations, ^**tachycardia,^** chest pain

• Slight increase in BP, followed by a drop in BP; diaphoresis

NURSING IMPLICATIONS

1. ^*Evaluate patient’s respiratory status and vital signs.^*

2. ^‡Explain to patient which type of medication is for long-term control and which one is for short-term response. Short-term preparations are used to treat and/or to prevent immediate problems; long-term preparations are given on a schedule for maintenance.^‡

3. SABA preparations are used to prevent an asthmatic attack and are not recommended for aborting an ongoing asthmatic attack.

4. ^*Advise patient not to use more doses than ordered.^*

5. Check with health care provider before using over-the-counter medicine.

6. ^‡Teach patient the correct use of inhalation devices—metered-dose inhalers (MDI), dry powder inhalers (DPI), and nebulizers.^‡

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