Antihistamines

Low or non-sedating antihistamines:
cetirizine (Zyrtec): desloratadine (Clarinex)
fexofenadine (Allegra): loratadine (Claritin):
Combination decongestant/antihistamine (Formulary)
Actifed (triprolidine 2.5mg + psuedoephedrine 60mg) Allegra D
Claritin-D  
Other antihistamines (Sedating)
chlorpheniramine (Chlor-Trimeton) clemastine (Tavist)
cyproheptadine (Periactin) dimenhydrinate (Dramamine):
diphenhydramine (Benadryl): hydroxyzine (Atarax, Vistaril)
promethazine (Phenergan)  

Low or non-sedating antihistamines:

cetirizine (Zyrtec): top of page icon
Metabolite of hydroxyzine. Usual dose: 5-10 mg orally once daily.

Children >/= 6 years and Adults:
Chronic urticaria, perennial or seasonal allergic rhinitis: 5-10 mg once daily, depending upon symptom severity

Elderly Initial: 5 mg once daily; may increase to 10 mg/day. Note: Manufacturer recommends 5 mg/day in patients >/= 77 years of age.

Dosage adjustment in renal/hepatic impairment:
Children <6 years: Cetirizine use not recommended
Children 6-11 years: <2.5 mg once daily
Children >/= 12 and Adults:
Clcr 11-31 mL/minute, hemodialysis, or hepatic impairment: Administer 5 mg once daily
Clcr<11 mL/minute, not on dialysis: Cetirizine use not recommended.

Supplied:
Syrup, as hydrochloride: 5 mg/5 mL (120 mL, 480 mL) [banana-grape flavor]
Tablet, as hydrochloride: 5 mg, 10 mg
Tablet, chewable, as hydrochloride: 5 mg, 10 mg [grape flavor]

desloratadine (Clarinex)  top of page icon
Adults:
Allergic rhinitis, seasonal/perennial: 5 mg po qd.
Chronic idiopathic urticaria: 5 mg po qd. In patients with liver or renal impairment, a starting dose of one 5 mg tablet every other day is recommended based on pharmacokinetic data.

Mechanism of Action
Desloratadine, a major metabolite of loratadine, is a long-acting tricyclic antihistamine with selective peripheral histamine H1 receptor antagonistic activity and additional anti-inflammatory properties.

Dosing: Oral:   Children:
6-11 months: 1 mg once daily
12 months to 5 years: 1.25 mg once daily
6-11 years: 2.5 mg once daily

Children >/= 12 years and Adults: 5 mg once daily

Supplied
Syrup (Clarinex®): 0.5 mg/mL (480 mL) [bubble gum flavor]

Tablet (Clarinex®): 5 mg

Tablet, orally-disintegrating (Clarinex® RediTabs®): 5 mg [contains phenylalanine 1.75 mg/tablet]

fexofenadine (Allegra):  top of page icon
Adult (usual) Chronic idiopathic urticaria: 60 mg orally twice daily.
Seasonal allergic rhinitis: 60 mg orally twice daily or 180 mg once daily. A dose of 60 mg once daily is recommended as the starting dose in patients with decreased renal function

Mechanism of Action
Fexofenadine is an active metabolite of terfenadine and like terfenadine it competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels and respiratory tract; it appears that fexofenadine does not cross the blood brain barrier to any appreciable degree, resulting in a reduced potential for sedation

Dosage - Oral:
Children 6-11 years: 30 mg twice daily

Children >/= 12 years and Adults:
Seasonal allergic rhinitis: 60 mg twice daily or 180 mg once daily
Chronic idiopathic urticaria: 60 mg twice daily

Supplied
Tablet, as hydrochloride: 30 mg, 60 mg, 180 mg

loratadine (Claritin):  top of page icon
Mechanism of Action
Long-acting tricyclic antihistamine with selective peripheral histamine H1-receptor antagonistic properties

Dosage
Oral: Seasonal allergic rhinitis, chronic idiopathic urticaria:
Children 2-5 years: 5 mg once daily

Children >/= 6 years and Adults: 10 mg once daily

Elderly: Peak plasma levels are increased; elimination half-life is slightly increased; specific dosing adjustments are not available

Dosage adjustment in renal impairment: Clcr </= 30 mL/minute:
Children 2-5 years: 5 mg every other day
Children >/= 6 years and Adults: 10 mg every other day

Supplied
Syrup (Claritin®): 1 mg/mL (120 mL) [contains sodium benzoate; fruit flavor]
Tablet (Alavert™, Claritin®, Claritin® Hives Relief; Tavist® ND): 10 mg
Tablet, rapidly-disintegrating: 10 mg
Alavert™: 10 mg [contains phenylalanine 8.4 mg/tablet]
Claritin® RediTabs®: 10 mg [mint flavor]
Dimetapp® Children's ND: 10 mg [contains phenylalanine 8.4 mg/tablet]

Combination decongestant/antihistamine (Formulary)

Actifed (triprolidine 2.5mg + psuedoephedrine 60mg):  top of page icon
Dosing (Adult): 1 tablet orally every 4 to 6 hours as needed.
Maximum of 4 tablets/day.

Allegra D top of page icon
(pseudoephedrine 120mg + fexofenadine 60mg).
 Dosing:: one tablet twice daily for adults and children 12 years of age and older (should be taken on an empty stomach).
A dose of one tablet once daily is recommended as the starting dose in patients with decreased renal function.

Claritin-D top of page icon
Claritin-D 24 hour (10mg loratadine + 240mg psuedophedrine)
Dosing (Adult): one tablet po qd.

Claritin-D 24 Hour Extended Release Tablets should generally be avoided in patients with hepatic insufficiency. Patients with renal insufficiency (GFR <30 L/min) should be given a lower initial dose (one tablet every other day) because they have reduced clearance of loratadine and pseudoephedrine. Patients who have a history of difficulty in swallowing tablets or who have known upper gastrointestinal narrowing or abnormal esophageal peristalsis should not use this product.

Other antihistamines (Sedating)

chlorpheniramine (Chlor-Trimeton)  top of page icon
Adult (usual): 4 mg po every 4 to 6 hrs; maximum dose: 24 mg/day. Sustained-release: 8 or 12 mg po every 8 to 12 hours. Maximum dose: 24 mg/day.
Supplied:
Extended Release Cap: 6 mg, 8 mg, 12 mg
Liquid/syrup: 2 mg/5 ml
Tablet: 2 mg, 4 mg. Chewable: 2 mg
EExtended Release tab: 8 mg, 12 mg, 16 mg

clemastine (Tavist)  top of page icon
Tavist 12 Hour Allergy Tablets: Clemastine fumarate, USP 1.34 mg (equivalent to 1 mg clemastine).

Adults and children 12 years of age and older: take 1 tablet every 12 hours, not more than 2 tablets in 24 hours unless directed by a doctor.

cyproheptadine (Periactin):  top of page icon
Mechanism of Action
A potent antihistamine and serotonin antagonist, competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract

Dosage - Oral: Children:
Allergic conditions: 0.25 mg/kg/day or 8 mg/m 2 /day in 2-3 divided doses or

2-6 years: 2 mg every 8-12 hours (not to exceed 12 mg/day)
7-14 years: 4 mg every 8-12 hours (not to exceed 16 mg/day)

Migraine headaches: 4 mg 2-3 times/day

Children >/= 12 years and Adults: Spasticity associated with spinal cord damage: 4 mg at bedtime; increase by a 4 mg dose every 3-4 days; average daily dose: 16 mg in divided doses; not to exceed 36 mg/day

Children >13 years and Adults: Appetite stimulation (anorexia nervosa): 2 mg 4 times/day; may be increased gradually over a 3-week period to 8 mg 4 times/day

Adults:
Allergic conditions: 4-20 mg/day divided every 8 hours (not to exceed 0.5 mg/kg/day)
Cluster headaches: 4 mg 4 times/day
Migraine headaches: 4-8 mg 3 times/day

Supplied
Syrup, as hydrochloride: 2 mg/5 mL (473 mL) [contains alcohol 5%; mint flavor]
Tablet, as hydrochloride: 4 mg

dimenhydrinate (Dramamine):  top of page icon
Mechanism of Action
Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract; blocks chemoreceptor trigger zone, diminishes vestibular stimulation, and depresses labyrinthine function through its central anticholinergic activity

Dosage  - Oral:  Children:
2-5 years: 12.5-25 mg every 6-8 hours, maximum: 75 mg/day
6-12 years: 25-50 mg every 6-8 hours, maximum: 150 mg/day

Adults: 50-100 mg every 4-6 hours, not to exceed 400 mg/day

Supplied
Caplet (TripTone®): 50 mg
Tablet (Dramamine®): 50 mg
Tablet, chewable (Dramamine®): 50 mg [contains phenylalanine 1.5 mg/tablet and tartrazine; orange flavor]

diphenhydramine (Benadryl):  top of page icon
Mechanism of Action
Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract; anticholinergic and sedative effects are also seen

Dosing- Children:   Oral, I.M., I.V.:
Treatment of moderate to severe allergic reactions: 5 mg/kg/day or 150 mg/m 2 /day in divided doses every 6-8 hours, not to exceed 300 mg/day

Minor allergic rhinitis or motion sickness:
2 to <6 years: 6.25 mg every 4-6 hours; maximum: 37.5 mg/day
6 to <12 years: 12.5-25 mg every 4-6 hours; maximum: 150 mg/day
>/= 12 years: 25-50 mg every 4-6 hours; maximum: 300 mg/day

Night-time sleep aid: 30 minutes before bedtime:
2 to <12 years: 1 mg/kg/dose; maximum: 50 mg/dose
>/= 12 years: 50 mg

Oral: Antitussive:
2 to <6 years: 6.25 mg every 4 hours; maximum 37.5 mg/day
6 to <12 years: 12.5 mg every 4 hours; maximum 75 mg/day
>/= 12 years: 25 mg every 4 hours; maximum 150 mg/day

 I.M., I.V.: Treatment of dystonic reactions: 0.5-1 mg/kg/dose

Adults:
Oral: 25-50 mg every 6-8 hours
Minor allergic rhinitis or motion sickness: 25-50 mg every 4-6 hours; maximum: 300 mg/day
Moderate to severe allergic reactions: 25-50 mg every 4 hours, not to exceed 400 mg/day
Nighttime sleep aid: 50 mg at bedtime

 I.M., I.V.: 10-50 mg in a single dose every 2-4 hours, not to exceed 400 mg/day
Dystonic reaction: 50 mg in a single dose; may repeat in 20-30 minutes if necessary

Topical: For external application, not longer than 7 days

Supplied
Elixir, as hydrochloride: 12.5 mg/5 mL (480 mL)
Caplet, as hydrochloride: 25 mg, 50 mg
Capsule, as hydrochloride: 25 mg, 50 mg
Injection, solution, as hydrochloride: 50 mg/mL (1 mL)
Solution, topical, as hydrochloride [spray] (Benadryl® Itch Stopping Extra Strength): 2% (60 mL) [contains zinc acetate 0.1%]
Tablet, chewable, as hydrochloride (Benadryl® Children's Allergy): 12.5 mg [contains phenylalanine 4.2 mg/tablet; grape flavor]
Tablet, orally-disintegrating, as citrate (Benadryl® Children's Allergy Fastmelt®): 19 mg [equivalent to diphenhydramine hydrochloride 12.5 mg; contains phenylalanine 4.5 mg/tablet and soy protein isolate; cherry flavor]

hydroxyzine  (Atarax, Vistaril): top of page icon
Adult (usual):
Antiemetic: I.M.: 25-100 mg/dose every 4-6 hours as needed.
Anxiety: Oral: 25-100 mg 4 times/day; maximum: 600 mg/day.
Preoperative sedation:  Oral: 50-100 mg. I.M.: 25-100 mg.
Management of pruritus: Oral: 25 mg 3-4 times/day

Administration
For I.M. administration in children, injections should be made into the midlateral muscles of the thigh;

SubQ, intra-arterial, and I.V. administration not recommended since thrombosis and digital gangrene can occur

promethazine  (Phenergan) top of page icon
Adult (usual)
Allergy: 25 mg orally at bedtime or 12.5 mg orally before meals and at bedtime. Allergy: 25 mg IV or IM, may repeat within 2 hrs if needed.
Anesthesia adjunct: 25-50 mg IM or IV prior to surgery.
Motion sickness: 25 mg orally twice daily.
Nausea and vomiting: 12.5-25 mg orally ,rectally, IV or IM every 4 to 6 hrs.
Sedation: 25-50 mg orally or 50 mg rectally.

Administration
Formulations available for oral, rectal, I.M./I.V. administration; not for SubQ or intra-arterial administration. Administer I.M. into deep muscle (preferred route of administration). Due to the possibility of orthostatic hypotension, I.V. administration is not the preferred route. Solution for injection may be diluted in 25-100 mL NS or D5W (maximum concentration of 25 mg/mL) and infused over 15-30 minutes at a rate </= 25 mg/minute.

[Supplied: 25, 50 mg/ml Injection. 12.5, 25, 50mg suppository. 10 mg/5 ml Syrup. 10, 25 , 50mg Tablet]
 

Disclaimer
Listed dosages are for - Adult patients ONLY. PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER. GlobalRPH does not directly or indirectly practice medicine or provide medical services and therefore assumes no liability whatsoever of any kind for the information and data accessed through the Service or for any diagnosis or treatment made in reliance thereon.

David F. McAuley, Pharm.D., R.Ph.  GlobalRPh Inc.

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