A-Z Drug Facts > Promethazine Hydrochloride/Phenylephrine Hydrochloride

Promethazine Hydrochloride / Phenylephrine Hydrochloride

Pronunciation: (proe-METH-a-zeen HYE-droe-KLOR-ide/FEN-il-EF-rin HYE-droe-KLOR-ide)
Class: Antihistamine, Decongestant

Trade Names:
Promethazine VC
- Syrup 5 mg phenylephrine hydrochloride/6.25 promethazine hydrochloride per 5 mL

Pharmacology

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Promethazine

Competitively antagonizes histamine at H ₁ -receptor sites and produces sedative as well as antiemetic effects.

Phenylephrine

Stimulates postsynaptic alpha-receptors, resulting in rise in arterial peripheral vasoconstriction.

Indications and Usage

Temporary relief of upper respiratory tract symptoms, including nasal congestion, associated with allergy or the common cold.

Contraindications

Treatment of lower respiratory tract symptoms, including asthma; patients with hypertension or peripheral vascular insufficiency; patients receiving MAOIs; known hypersensitivity or an idiosyncratic reaction to promethazine or other phenothiazines; allergy to any component of the product; children younger than 2 yr of age.

Dosage and Administration

Adults and Children 12 yr of age and older

PO 1 tsp (5 mL) every 4 to 6 h (max, 6 tsp [30 mL] in 24 h).

Children 6 to younger than 12 yr of age

PO ½ to 1 tsp (2.5 to 5 mL) every 4 to 6 h (max, 6 tsp [30 mL] in 24 h).

Children 2 to younger than 6 yr of age

PO ¼ to ½ tsp (1.25 to 2.5 mL) every 4 to 6 h.

General Advice

• Give with food or milk if GI upset occurs.
• Use dosing spoon or syringe for pediatric doses.

Storage/Stability

Store syrup at controlled room temperature (68° to 77°F). Keep tightly capped and protect from light.

Drug Interactions

Promethazine Alcohol, barbiturates, narcotic analgesics, sedative-hypnotics, tricyclic antidepressants, tranquilizers, or other CNS depressants

Sedative effects of promethazine is additive with these agents.

Anticholinergics

May decrease action of promethazine.

Barbiturate anesthetics

Coadministration with promethazine may increase the risk of neuromuscular excitation and hypotension.

Epinephrine

Because promethazine may reverse the vasopressor effect of epinephrine, do not use epinephrine to treat promethazine-associated overdose.

MAOIs

Coadministration with promethazine may prolong and intensify anticholinergic effects; may cause hypotension and extrapyramidal effects.

Phenylephrine Alpha-adrenergic blockers (eg, phentolamine)

Decreased pressor response.

Anorexiants (eg, amphetamines, phenylpropanolamine)

Synergistic adrenergic response.

Atropine

Reflex bradycardia may be blocked or pressor response enhanced.

Beta-adrenergic blockers (eg, propranolol)

Cardiostimulating effects may be blocked.

Bronchodilators, sympathomimetic agents

Tachycardia or other arrhythmias may occur.

Ergot derivatives

Excessive increase in BP may occur.

MAOIs (eg, isocarboxazid)

Because acute hypertensive crisis may occur, coadministration of these agents is contraindicated.

Tricyclic antidepressants

Pressor effects of phenylephrine may be increased.

Laboratory Test Interactions

False-negative or false-positive interpretations of diagnostic pregnancy tests based on immunological reactions between human chorionic gonadotropin (hCG) and anti-hCG; increased blood glucose tests.

Adverse Reactions

Cardiovascular

Phenylephrine

Hypertension.

Promethazine

Bradycardia, decreased and increased BP, faintness, tachycardia.

CNS

Phenylephrine

Anxiety, dizziness, nervousness, restlessness, tremor, weakness.

Promethazine

Catatonic-like states, confusion, convulsive seizures, disorientation, dizziness, drowsiness, euphoria, excitation, extrapyramidal symptoms (including oculogyric crisis, tongue protrusion, and torticollis), fatigue, hallucinations, hysteria, incoordination, insomnia, lassitude, nervousness, sedation, somnolence, tremor.

Dermatologic

Promethazine

Dermatitis, photosensitivity, urticaria.

EENT

Promethazine

Blurred vision, diplopia, nasal stuffiness, tinnitus.

Promethazine

Nasal stuffiness, tinnitus.

GI

Phenylephrine

Precordial pain.

Promethazine

Dry mouth, nausea, vomiting.

Hematologic-Lymphatic

Promethazine

Agranulocytosis, leukopenia, thrombocytopenia, thrombocytopenic purpura.

Hepatic

Jaundice (including cholestatic).

Respiratory

Phenylephrine

Respiratory distress.

Promethazine

Asthma, potentially fatal apnea and respiratory depression.

Miscellaneous

Promethazine

Angioneurotic edema, paradoxical reactions (including abnormal movements and hyperexcitability with agitated behavior, delirium, nightmares, and respiratory distress in some patients), potentially fatal neuroleptic malignant syndrome.

Precautions

Warnings Because of potential for fatal respiratory depression, do not administer promethazine to children younger than 2 yr of age. Administer with caution to children older than 2 yr of age.

Pregnancy

Category C .

Lactation

Undetermined.

Children

Contraindicated in children younger than 2 yr of age.

Elderly

Use with caution, usually starting at low end of dosage range, because of the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Special Risk Patients

Use with caution in patients with bone marrow suppression, narrow-angle glaucoma, pyloroduodenal obstruction, stenosing peptic ulcer, urinary bladder obstruction due to symptomatic prostatic hypertrophy or narrowing of the bladder neck, arteriosclerosis, thyroid disease, diabetes mellitus, CV disease, or hepatic function impairment.

Cholestatic jaundice

May occur.

Extrapyramidal symptoms

Extrapyramidal symptoms that can occur secondary to promethazine may be confused with the CNS signs of undiagnosed primary disease (eg, encephalopathy, Reye syndrome). Avoid use in children whose signs and symptoms may suggest Reye syndrome or other hepatic diseases.

Neuroleptic malignant syndrome

Has occurred and is potentially fatal. Signs and symptoms include altered mental status, diaphoresis, hyperpyrexia, irregular BP and pulse, muscle rigidity, and tachycardia.

Seizure threshold

Seizure threshold may be lowered, use with caution in persons with known seizure disorders or when given in combination with narcotics or local anesthetics that may also affect seizure threshold.

Sleep apnea

Avoid use in patients with history of sleep apnea.

Overdosage

Symptoms

Phenylephrine

Cerebral hemorrhage, convulsions, headache, hypertension, ventricular premature beats and short paroxysms of ventricular tachycardia, vomiting.

Promethazine

Ataxia, athetosis, extensor plantar reflexes, hyperreflexia, hypertonia, mild depression of CNS and CV system to profound hypotension, respiratory depression, unconsciousness, and sudden death. Stimulation may be evident, especially in children and elderly patients. Convulsions, dry mouth, fixed dilated pupils, flushing, GI symptoms, paradoxical reaction characterized by hyperexcitability and nightmares in children.

Patient Information

• Advise patient to take prescribed dose every 4 to 6 h as needed.
• Advise caregiver to use dosing spoon or syringe when giving suspension to children.
• Advise patient to take with food or milk if GI upset occurs.
• Advise patient that if a dose is missed, to take as soon as remembered unless it is nearing time for next dose. Caution patient to not double the dose to catch up.
• Advise patient that if allergy symptoms are not controlled, not to increase the dose of medication but to inform health care provider.
• Caution patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
• Advise patient to avoid alcohol and other CNS depressants because of risk of excessive sedation.
• Caution patient not to take any OTC antihistamines or decongestants while taking this medication unless advised by health care provider.
• If patient is to have allergy skin testing, advise not to take the medication for at least 6 days before skin testing.
• Caution patient that medication may cause sensitivity to sunlight and to avoid unnecessary exposure to ultraviolet (UV) light (eg, sunlight, tanning booths) and to use sunscreen and wear protective clothing when exposed to UV light until tolerance is determined.
• Instruct patient to stop taking drug and immediately report any of these symptoms to health care provider: abnormal muscle movements, unusual sensitivity to sunlight, nervousness, dizziness, excessive drowsiness.

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