ANTIHISTAMINES – Flashcards

Relief of allergic symptoms caused by histamine release including: Seasonal and perennial allergic rhinitis, Chronic urticaria.

Antagonizes the effects of histamine at H1-receptor sites; does not bind to or inactivate histamine. Anticholinergic effects are minimal and sedation is dose-related. Therapeutic Effects: Decreased symptoms of histamine excess (sneezing, rhinorrhea, ocular tearing and redness, pruritus).

CNS: dizziness, drowsiness (significant with doses > 10 mg/day), fatigue. EENT: pharyngitis. GI: dry mouth.

Assess allergy symptoms before and during therapy. Assess lung sounds and character of bronchial secretions. Maintain fluid intake of 1500-2000 mL/day to decrease viscosity of secretions. Lab Test Considerations: May cause false-negative result in allergy skin testing. Administer once daily without regard to food. Instruct patient to contact health care professional if dizziness occurs or if symptoms persist.

PO (Adults and children >6 yr): 5-10 mg given once or divided twice daily. {Hepatic/Renal Impairment PO (Adults and Children >12 yr): CCr ≤31 mL/min, hepatic impairment or hemodialysis—5 mg once daily.}

Drug-Drug: Additive CNS depression may occur with alcohol, opioid analgesics, or sedative/hypnotics. Theophylline may decrease clearance and increase toxicity.

Contraindicated in: Hypersensitivity to cetirizine, hydroxyzine or any component; Lactation: Excreted in breast milk; not recommended for use. Use Cautiously in: Patients with hepatic or renal impairment (dosage reduction recommended if CCr ≤31 mL/min or hepatic function is impaired); OB/Pedi: Safety not established for pregnant women or children <6 mo; Geri: Initiate at lower doses.

Therapeutic: allergy, cold, and cough remedies, antihistamines Pharmacologic: piperazines (peripherally selective)

Relief of allergic symptoms caused by histamine release, including: Nasal allergies, Allergic dermatoses. Management of severe allergic or hypersensitivity reactions, including anaphylaxis and transfusion reactions.

Antagonizes the effects of histamine at H2-receptor sites; does not bind to or inactivate histamine. Decreased symptoms of histamine excess (sneezing, rhinorrhea, nasal and ocular pruritus, ocular tearing, and redness).

CNS: drowsiness, dizziness, excitation (in children). EENT: blurred vision. CV: hypertension, arrhythmias, hypotension, palpitations. GI: dry mouth, constipation, obstruction. GU: retention, urinary hesitancy.

Assess allergy symptoms (rhinitis, conjunctivitis, hives) prior to and periodically during therapy. Monitor pulse and BP before initiating and throughout IV therapy. Geri: Assess for adverse anticholinergic effects (delirium, acute confusion, dizziness, dry mouth, blurred vision, urinary retention, constipation, tachycardia). Assess lung sounds and character of bronchial secretions. Maintain fluid intake of 1500-2000 mL/day to decrease viscosity of secretions. May cause false-negative reactions on allergy skin tests; discontinue 4 days prior to testing. PO: Administer oral doses with food or milk to decrease GI irritation. Extended-release tablets and capsules should be swallowed whole; do not crush, break, or chew. Chewable tablets should not be swallowed whole; chew well before swallowing. SC, IM: The 100-mg/mL solution is recommended for IM or subcut routes only. The 10-mg/mL solution may be used for IM, subcut, or IV. IV: Diluent: May be given undiluted. Use only the 10 mg/mL strength for IV administration. Concentration: 10 mg/mL. Administer each 10-mg dose over at least 1 min. Caution parents to avoid OTC cough and cold products while breastfeeding or to children <4 yrs. Advise patient that good oral hygiene, frequent rinsing of mouth with water, and sugarless gum or candy may help relieve dryness of mouth.

PO (Adults): 4 mg q 4-6 hr or 8-12 mg of extended-release formulation q 8-12 hr (not to exceed 24 mg/day) (Geriatric Patients): 4 mg twice daily or 8 mg of extended-release formulation at bedtime..

Drug-Drug: ↑ CNS depression with other CNS depressants , including alcohol , opioid analgesics , and sedative/hypnotics. MAO inhibitors intensify and prolong anticholinergic effects of antihistamines. ↑ anticholinergic effects with other drugs possessing anticholinergic properties , including antidepressants , atropine , haloperidol , phenothiazines , quinidine , and disopyramide .

Contraindicated in: Hypersensitivity; Acute attacks of asthma; Lactation: Avoid use or use alternative feeding method; Known alcohol intolerance (some liquid forms). Use Cautiously in: Angle-closure glaucoma; Liver disease; Geri: Appears on Beers list. Geriatric patients are more susceptible to adverse reactions due to anticholinergic effects; OB: Safety not established.

Therapeutic: antihistamines

Relief of symptoms of seasonal allergies. Management of chronic idiopathic urticaria. Management of hives.

Blocks peripheral effects of histamine released during allergic reactions. Decreased symptoms of allergic reactions (nasal stuffiness; red, swollen eyes, itching).

CNS: confusion, drowsiness (rare), paradoxical excitation. EENT: blurred vision. GI: dry mouth, GI upset. Derm: Photosensitivity, rash. Metabolic: weight gain.

Assess allergy symptoms (rhinitis, conjunctivitis, hives) before and periodically during therapy. Assess lung sounds and character of bronchial secretions. Maintain fluid intake of 1500-2000 mL/day to decrease viscosity of secretions. May cause false-negative result on allergy skin testing. Administer once daily. For rapidly disintegrating tablets (Alavert, Claritin Reditabs)—place on tongue. Tablet disintegrates rapidly. May be taken with or without water. Caution patient to use sunscreen and protective clothing to prevent photosensitivity reactions. Advise patient to avoid taking alcohol or other CNS depressants concurrently with this drug. Advise patient that good oral hygiene, frequent rinsing of mouth with water, and sugarless gum or candy may minimize dry mouth. Patient should notify dentist if dry mouth persists >2 wk. Instruct patient to contact health care professional immediately if dizziness, fainting, or fast or irregular heartbeat occurs or if symptoms persist.

PO (Adults and Children ≥6 yr): 10 mg once daily. Renal Impairment: PO (Adults): CCr <30 mL/min—10 mg every other day. Hepatic Impairment: PO (Adults): 10 mg every other day.

Drug-Drug: The following interactions may occur, but are less likely to occur with loratidine than with more sedating antihistamines. MAO inhibitors may intensify and prolong effects of antihistamines. ↑ CNS depression may occur with other CNS depressants, including alcohol , antidepressants , opioid analgesics, and sedative/hypnotics. Amiodarone may ↑ loratadine levels and ↑ risk of QTc interval prolongation Drug-Natural Products Kava-kava , valerian , or chamomile can ↑ CNS depression.

Contraindicated in: Hypersensitivity. Use Cautiously in: Hepatic impairment or CCr <30 mL/min (↓ dose to 10 mg every other day); Lactation: Usually compatible with breastfeeding (AAP); OB: Pregnancy or children <2 yr (safety not established). Syrup contains sodium benzoate, avoid use in neonates; Geri: ↑ risk of adverse reactions.

Therapeutic: antihistamines

Relief of symptoms of seasonal allergic rhinitis. Management of chronic idiopathic urticaria.

Antagonizes the effects of histamine at peripheral histamine-1 (H1) receptors, including pruritus and urticaria. Also has a drying effect on the nasal mucosa. Decreased sneezing, rhinorrhea, itchy eyes, nose, and throat associated with seasonal allergies. Decreased urticaria.

CNS: drowsiness, fatigue. GI: dyspepsia. Endo: dysmenorrhea.

Assess allergy symptoms (rhinitis, conjunctivitis, hives) before and periodically during therapy. Assess lung sounds and character of bronchial secretions. Maintain fluid intake of 1500-2000 mL/day to decrease viscosity of secretions. Will cause false-negative reactions on allergy skin tests; discontinue 3 days before testing. Administer with food or milk to decrease GI irritation. Capsules and tablets should be taken with water or milk, not juice.

PO (Adults and Children ≥12 yr): 60 mg twice daily, or 180 mg once daily. Renal Impairment: PO (Adults): 60 mg once daily as a starting dose.

Drug-Drug: Magnesium and aluminum-containing antacids ↓ absorption and may decrease effectiveness. Drug-Food: Apple, orange, and grapefruit juice ↓ absorption and may decrease effectiveness

Contraindicated in: Hypersensitivity. Use Cautiously in: Impaired renal function (increased dosing interval recommended); OB: use only if maternal benefit outweighs potential risk to fetus; Lactation: Usually compatible with breastfeeding (AAP).

Therapeutic: allergy, cold, and cough remedies, antihistamines