PBZ-SR, Pelamine, Pyribenzamine
Classifications: antihistamine; h1-receptor antagonist; Therapeutic: antihistamine; h1-receptor antagonist
Pregnancy Category: B
25 mg, 50 mg tablets; 100 mg sustained release tablets
Antihistamine with mild CNS depressant effects. Antagonizes histamine action (i.e., increased capillary permeability, edema
formation, itching, and constriction of respiratory, GI, and vascular smooth muscle).
Has antihistamine, antitussive, anticholinergic, and local anesthetic action.
To relieve symptoms of various allergic conditions, to ameliorate reactions to blood or plasma, and in anaphylaxis as adjunct
to epinephrine and other standard measures after acute symptoms have been controlled. Also to provide oral mucous membrane
analgesia in young children with herpetic gingiva-stomatitis.
Narrow-angle glaucoma; symptomatic prostatic hypertrophy; bladder neck obstruction; GI obstruction or stenosis; lower respiratory
tract symptoms, including asthma; within 14 d of MAO inhibitor therapy. Safe use in neonates and premature infants is not
History of asthma; convulsive disorders; increased intraocular pressure; hyperthyroidism; cardiovascular disease; hypertension;
diabetes mellitus; pregnancy (category B), lactation.
Route & Dosage
Adult: PO 2550 mg q46h or 100 mg sustained release q812h (max: 600 mg/d)
Child: PO 5 mg/kg/d in 46 divided doses (max: 300 mg/d)
- Give with or immediately after meals or food or with a glass of milk or water to lessen GI adverse effects.
- Do not use sustained release formulation (100 mg) with children of any age.
- Do not crush, break, or chew sustained release tablets. These must be swallowed whole.
- Store in tight, light-resistant containers.
Adverse Effects (≥1%) Respiratory:
Thickened bronchial secretions, wheezing, sensation of chest tightness. Special Senses:
Blurred vision, diplopia
Urinary hesitancy or retention; dysuria. CV:
Palpitation, tachycardia, mild hypotension or hypertension, cardiovascular collapse. CNS: Drowsiness,
dizziness, tinnitus, vertigo, fatigue
, headache; disturbed coordination, tingling, tremors, euphoria, nervousness, restlessness,
, hallucinations, excitement. GI: Epigastric distress, anorexia, nausea, vomiting, constipation
, dry mouth, nose,
and throat. Hematologic: Leukopenia
, hemolytic anemia
Skin rash, urticaria, photosensitivity. Body as a Whole: Anaphylactic shock,
fever, ataxia, athetosis, convulsions, coma.
and other cns depressants
add to CNS
depression; mao inhibitors
may intensify anticholinergic effects.
Readily from GI tract. Onset:
1530 min. Peak:
23 h. Duration:
46 h (up to 8 h with sustained release). Distribution:
Crosses placenta; distributed into breast milk. Metabolism:
In liver. Elimination:
Assessment & Drug Effects
- Assist older adults during ambulation; dizziness, sedation, and hypotension are more likely to occur in this age group.
- Lab tests: Obtain periodic blood cell counts during long-term therapy with antihistamines.
Patient & Family Education
- Void just before taking drug if urinary hesitancy is a problem.
- Do not drive or engage in potentially hazardous activities until response to drug is known. Mild to moderate drowsiness,
blurred vision, and dizziness occur in some patients.
- Be aware that the effects of antihistamines may be augmented by concomitant use of alcohol or other CNS depressants.
- Do not take OTC preparations without consulting physician.
- Discontinue antihistamines within 4 d before skin testing procedure for allergy because drug may interfere with reactions
and obscure test results.