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Monday, February 7, 2011

Diphenhydramine hydrochloride

Posted by Sampil 5:23 PM, under | No comments

diphenhydramine hydrochloride
(dye fen hye' dra meen)
Oral:
Allerdryl (CAN), AllerMax Caplets, Banophen, Banophen Allergy, Benadryl Allergy, Diphen AF, DiphenhistDiphenhist Captabs,GenahistSiladrylSilphen Cough
Oral prescription preparations:
Benadryl, Tusstat
Parenteral preparations:
Benadryl

Pregnancy Category B

Drug classes
Antihistamine
Anti-motion sickness drug
Sedative-hypnotic
Antiparkinsonian
Cough suppressant

Therapeutic actions
Competitively blocks the effects of histamine at H1-receptor sites, has atropine-like, antipruritic, and sedative effects.

Indications
·        Relief of symptoms associated with perennial and seasonal allergic rhinitis; vasomotor rhinitis; allergic conjunctivitis; mild, uncomplicated urticaria andangioedema; amelioration of allergic reactions to blood or plasma; dermatographism; adjunctive therapy in anaphylactic reactions
·        Active and prophylactic treatment of motion sickness
·        Nighttime sleep aid
·        Parkinsonism (including drug-induced parkinsonism and extrapyramidal reactions), in the elderly intolerant of more potent drugs, for milder forms of the disorder in other age groups, and in combination with centrally acting anticholinergic antiparkinsonian drugs
·        Syrup formulation: Suppression of cough due to colds or allergy

Contraindications and cautions
·        Contraindicated with allergy to any antihistamines, third trimester of pregnancy, lactation.
·        Use cautiously with narrow-angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, asthmatic attack, bladder neck obstruction,pyloroduodenal obstruction, pregnancy; elderly patients who may be sensitive to anticholinergic effects.

Available forms
Capsule soft gels—25 mg; capsules—25, 50 mg; tablets—25, 50 mg; chewable tablets—12.5 mg; elixir—12.5 mg/5 mL; syrup—12.5 mg/5 mL; liquid—6.25, 12.5 mg/5 mL; injection—10, 50 mg/ mL; solution—12.5 mg/5 mL

Dosages
ADULTS
Oral
25–50 mg q 4–8 hr PO.
·        Motion sickness: Give full dose prophylactically 30 min before exposure to motion, and repeat before meals and hs.
·        Nighttime sleep aid: 25–50 mg PO hs.
·        Cough suppression: 25 mg q 4 hr PO, not to exceed 150 mg in 24 hr.
Parenteral
10–50 mg IV or deep IM or up to 100 mg if required. Maximum daily dose is 400 mg.
PEDIATRIC PATIENTS > 10 KG OR 20 LB
Oral
12.5–25 mg tidqid PO or 5 mg/kg/day PO or 150 mg/mper day PO. Maximum daily dose 300 mg.
·        Motion sickness: Give full dose prophylactically 30 min before exposure to motion and repeat before meals and hs.
·        Cough suppression:
2–6 yr: 6.25 mg q 4 hr, not to exceed 25 mg in 24 hr.
6–12 yr: 12.5 mg q 4 hr PO, not to exceed 75 mg in 24 hr.
Parenteral
5 mg/kg/day or 150 mg/m2 per day IV or by deep IM injection. Maximum daily dose is 300 mg divided into four doses.
GERIATRIC PATIENTS
More likely to cause dizziness, sedation, syncope, toxic confusional states, and hypotension in elderly patients; use with caution.

Pharmacokinetics
Route
Onset
Peak
Duration
Oral
15–30 min
1–4 hr
4–7 hr
IM
20–30 min
1–4 hr
4–8 hr
IV
Rapid
30–60 min
4–8 hr

Metabolism: Hepatic; T1/2: 2.5–7 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Urine

IV facts
Preparation: No additional preparation required.
Infusion: Administer slowly each 25 mg over 1 min by direct injection or into tubing of running IV.
Incompatibilities: Do not combine with amobarbitalamphotericin B, cephalothin, hydrocortisone, phenobarbitalphenytoin, thiopental.
Y-site incompatibilities: Do not mix with foscarnet.

Adverse effects
·        CNS: Drowsiness, sedation, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, headache, blurred vision,diplopia
·        CV: Hypotension, palpitations, bradycardia, tachycardia, extrasystoles
·        GI: Epigastric distress, anorexia, increased appetite and weight gain, nausea, vomiting, diarrhea or constipation
·        GU: Urinary frequency, dysuria, urinary retention, early menses, decreased libido, impotence
·        HematologicHemolytic anemia, hypoplastic anemia, thrombocytopenia, leukopeniaagranulocytosispancytopenia
·        Respiratory: Thickening of bronchial secretions, chest tightness, wheezing, nasal stuffiness, dry mouth, dry nose, dry throat, sore throat
·        Other: Urticaria, rash, anaphylactic shock, photosensitivity, excessive perspiration

Interactions
·        Possible increased and prolonged anticholinergic effects with MAOIs

Nursing considerations
Assessment
·        History: Allergy to any antihistamines, narrow-angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, asthmatic attack, bladder neck obstruction, pyloroduodenal obstruction, third trimester of pregnancy, lactation
·        Physical: Skin color, lesions, texture; orientation, reflexes, affect; vision examination; P, BP; R, adventitious sounds; bowel sounds; prostate palpation; CBC with differential

Interventions
·        Administer with food if GI upset occurs.
·        Administer syrup form if patient is unable to take tablets.
·        Monitor patient response, and arrange for adjustment of dosage to lowest possible effective dose.

Teaching points
·        Take as prescribed; avoid excessive dosage.
·        Take with food if GI upset occurs.
·        Avoid alcohol; serious sedation could occur.
·        You may experience these side effects: Dizziness, sedation, drowsiness (use caution driving or performing tasks requiring alertness); epigastric distress, diarrhea or constipation (take drug with meals); dry mouth (use frequent mouth care, suck sugarless lozenges); thickening of bronchial secretions, dryness of nasal mucosa (use a humidifier).
·        Report difficulty breathing, hallucinations, tremors, loss of coordination, unusual bleeding or bruising, visual disturbances, irregular heartbeat.

Adverse effects in Italic are most common; those in Bold are life-threatening.

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