Telfast

Action

Blocks effects of histamine at peripheral histamine₁-receptor sites, decreasing allergy signs and symptoms

Availability

Capsules: 60 mg

Oral suspension: 30 mg/5 ml (6 mg/ml)

Tablets: 30 mg, 60 mg, 180 mg

Tablets (orally disintegrating): 30 mg

Indications and dosages

➣ Seasonal allergic rhinitis; chronic idiopathic urticaria

Adults and children age 12 and older: 60 mg P.O. b.i.d. or 180 mg once daily (conventional tablets)

Children ages 6 to 11: 30 mg P.O. b.i.d. (conventional tablets or ODT tablets)

➣ Seasonal allergic rhinitis

Children ages 2 to 11: 30 mg P.O. b.i.d. (oral suspension and ODT)

➣ Chronic idiopathic urticaria

Children ages 6 months to less than 2 years: 15 mg P.O. b.i.d.(oral suspension and ODT)

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug, terfenadine, or their components

Precautions

Use cautiously in:

• renal impairment

• concurrent ketoconazole or erythromycin therapy

• elderly patients

• pregnant or breastfeeding patients.

Administration

• Give capsules and conventional tablets with water; don't give with apple, orange, or grapefruit juice.

• Don't remove orally disintegrating tablets from original blister package until time of administration.

• Administer orally disintegrating tablets on an empty stomach; allow tablets to disintegrate on the tongue and then have patient swallow tablets with or without water.

• Don't break or use partial orally disintegrating tablets

• Know that orally disintegrating tablets contain phenylalanine.

• Don't give antacids within 2 hours of fexofenadine.

Adverse reactions

CNS: drowsiness, fatigue, headache

EENT: otitis media

GI: nausea, dyspepsia

Metabolic: dysmenorrhea

Respiratory: upper respiratory tract infection

Other: viral infection

Interactions

Drug-drug. Antacids containing aluminum and magnesium: decreased absorption and efficacy of fexofenadine

Drug-diagnostic tests. Skin allergy tests: false-negative results

Drug-food. Apple, orange, and grapefruit juice: decreased absorption and efficacy of fexofenadine

Patient monitoring

• Monitor renal function.

• Watch for signs and symptoms of viral infection.

Patient teaching

• Instruct patient to take conventional tablets with water, and not with apple, orange, or grapefruit juice.

• Instruct patient not to remove orally disintegrating tablets from original blister package until time of administration.

• Instruct patient to take orally disintegrating tablets on an empty stomach at least 1 hour before or 2 hours after a meal, to allow tablet to disintegrate on the tongue, and then to swallow with or without water. Advise patient not to chew tablets.

• Tell patient not to break or use partial orally disintegrating tablets.

• Tell patient to stop taking drug 4 days before diagnostic skin tests, to avoid interference with test results.

• Advise patient to report signs or symptoms of viral infection, especially upper respiratory tract infection.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Advise female patient to inform prescriber if she is pregnant or breastfeeding.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.