diphenhydrAMINE hydrochloride (redirected from Aler-Dryl)

diphenhydrAMINE hydrochloride,

an antihistamine.

indications It is prescribed in the treatment of hypersensitivity reactions, including rhinitis, skin rash, and pruritus, and in the treatment of motion sickness and insomnia.

contraindications Asthma or known hypersensitivity to this drug prohibits its use. It is not given to newborns or lactating mothers.

adverse effects Among the more serious adverse reactions are skin rash, hypersensitivity reactions, and tachycardia. Drowsiness and dry mouth commonly occur.

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diphenhydramine hydrochloride

Adult Chesty Cough (UK), Aler-Cap, Aler-Dryl, Allerdryl (CA), AllerMax, Banophen, Benadryl, Benadryl Allergy, Benadryl Child Chesty Cough (UK), Benadryl Dye-Free Allergy, Children's Allergy Fastmelt, Compoz Nighttime Sleep Aid, Dreemon (UK), Diphen AF, Diphenhist, Histergan (UK), Hydramine, Genahist, Mandalyn Paedetriac (UK), Paxidorm (UK), PMS-Diphenhydramine (CA), Nightcalm, Nytol, Siladryl, Simply Sleep, Sleep Aid (UK), Sleepeaze (UK), Sominex, Twilite, Unisom Maximum Strength SleepGels

Pharmacologic class: Ethanolamine derivative, nonselective histamine₁-receptor antagonist

Therapeutic class: Antihistamine, antitussive, antiemetic, antivertigo agent, antidyskinetic

Pregnancy risk category B

Action

Interferes with histamine effects at histamine₁-receptor sites; prevents but doesn't reverse histamine-mediated response. Also possesses CNS depressant and anticholinergic properties.

Availability

Capsules: 25 mg, 50 mg

Elixir: 12.5 mg/5 ml

Injection: 10 mg/ml, 50 mg/ml

Syrup: 12.5 mg/5 ml

Tablets: 25 mg, 50 mg

Tablets (chewable): 12.5 mg, 25 mg

⊘Indications and dosages

➣ Allergy symptoms caused by histamine release (including anaphylaxis, seasonal and perennial allergic rhinitis, and allergic dermatoses); nausea; vertigo

Adults and children over age 12: 25 to 50 mg P.O. q 4 to 6 hours, or 10 to 50 mg I.V. or I.M. q 2 to 3 hours p.r.n. (Some patients may need up to 100 mg.) Don't exceed 400 mg/day.

Children ages 6 to 12: 12.5 to 25 mg P.O. q 4 to 6 hours, or 1.25 mg/kg (37.5 mg/m²) I.M. or I.V. q.i.d. Don't exceed 150 mg/day.

Children ages 2 to 5: 6.25 mg P.O. q 4 to 6 hours. Don't exceed 37.5 mg/day.

➣ Cough

Adults: 25 mg P.O. q 4 hours p.r.n. Don't exceed 150 mg/day.

Children ages 6 to 12: 12.5 mg P.O. q 4 hours. Don't exceed 75 mg/day.

Children ages 2 to 5: 6.25 mg P.O. q 4 hours. Don't exceed 37.5 mg/24 hours.

➣ Dyskinesia; Parkinson's disease

Adults: Initially, 25 mg P.O. t.i.d.; may be increased to a maximum of 50 mg q.i.d.

➣ Mild nighttime sedation

Adults: 50 mg P.O. 20 to 30 minutes before bedtime

Dosage adjustment

• Elderly patients

Off-label uses

• Drug-induced extrapyramidal reactions

Contraindications

• Hypersensitivity to drug
• Alcohol intolerance
• Acute asthma attacks
• MAO inhibitor use within past 14 days
• Breastfeeding

Precautions

Use cautiously in:
• severe hepatic disease, angle-closure glaucoma, seizure disorders, prostatic hypertrophy
• elderly patients
• pregnant patients (safety not established).

Administration

• For motion sickness, administer 30 minutes before activity.
• Give oral doses with food or milk to minimize adverse GI effects.
• For I.V. use, check compatibility before mixing with other drugs.
• Inject I.M. dose deep into large muscle mass; rotate sites.
• Discontinue drug 4 days before allergy skin testing to avoid misleading results.
☞ Don't give within 14 days of MAO inhibitors.

Route	Onset	Peak	Duration
P.O.	15-60 min	1-4 hr	4-8 hr
I.V.	Rapid	Unknown	4-8 hr
I.M.	20-30 min	1-4 hr	4-8 hr

Adverse reactions

CNS: drowsiness, dizziness, headache, paradoxical stimulation (especially in children)

CV: hypotension, palpitations

EENT: blurred vision, tinnitus

GI: diarrhea, constipation, dry mouth

GU: dysuria, urinary frequency or retention

Skin: photosensitivity

Other: decreased appetite, pain at I.M. injection site

Interactions

Drug-drug. Antihistamines, opioids, sedative-hypnotics: additive CNS depression

Disopyramide, quinidine, tricyclic antidepressants: increased anticholinergic effects

MAO inhibitors: intensified and prolonged anticholinergic effects

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

Hemoglobin, platelets: decreased values

Drug-herbs. Angel's trumpet, jimson weed, scopolia: increased anticholinergic effects

Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Drug-behaviors. Alcohol use: increased CNS depression

Patient monitoring

• Monitor cardiovascular status, especially in patients with cardiovascular disease.
• Supervise patient during ambulation. Use side rails as necessary.

Patient teaching

• Advise patient to take drug with food if it causes GI upset.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.