Phenergan

Phenergan - General Information

A phenothiazine derivative with histamine H1-blocking, antimuscarinic, and sedative properties. It is used as an antiallergic, in pruritus, for motion sickness and sedation, and also in animals. [PubChem]

Pharmacology of Phenergan

Phenergan, a phenothiazine, is an H1-antagonist with anticholinergic, sedative, and antiemetic effects and some local anesthetic properties. Phenergan is used as an antiemetic or to prevent motion sickness.

Phenergan for patients

Promethazine hydrochloride is used to treat allergic symptoms, to prevent nausea and vomiting, with other medicines to treat pain, prevent motion sickness. The major side reaction of this drug is sedation. Promethazine can cause significant sedation. It is advised that you not drink alcohol or take other medications that may make you drowsy or uncoordinated. Care should be taken while driving until it is known that the drug effects will not interfere. This medication can be taken with food to prevent stomach irritation. If this drug is taken to prevent motion sickness it should be taken 30 minutes prior to the event.

Syrup, Tablets and Suppositories:

Phenergan Tablets and Suppositories may cause marked drowsiness or impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The use of alcohol or other central-nervous-system depressants such as sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers, may enhance impairment. Pediatric patients should be supervised to avoid potential harm in bike riding or in other hazardous activities.

Patients should be advised to report any involuntary muscle movements.

Avoid prolonged exposure to the sun.

Phenergan Interactions

Injection:

Narcotics And Barbiturates: The CNS-depressant effects of narcotics are additive with promethazine hydrochloride.

Monoamine Oxidase Inhibitors (Maoi): Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAOI and phenothiazines are used concomitantly. Although such a reaction has not been reported with promethazine, the possibility should be considered.

Syrup, Tablets and Suppositories:

CNS Depressants - Phenergan Tablets and Suppositories may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine HCl. When given concomitantly with Phenergan Tablets and Suppositories, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine HCl relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain.

Epinephrine - Because of the potential for Phenergan to reverse epinephrineís vasopressor effect, epinephrine should NOT be used to treat hypotension associated with Phenergan Tablets and Suppositories overdose.

Anticholinergics - Concomitant use of other agents with anticholinergic properties should be undertaken with caution.

Monoamine Oxidase Inhibitors (MAOI) - Drug interactions, including an increased incidence of extrapyramidal effects, have been reported when some MAOI and phenothiazines are used concomitantly. This possibility should be considered with Phenergan Tablets and Suppositories.

Phenergan Contraindications

Injection: Promethazine is contraindicated in comatose states, in patients who have received large amounts of central-nervous-system depressants (alcohol, sedative hypnotics, including barbiturates, general anesthetics, narcotics, narcotic analgesics, tranquilizers, etc.), and in patients who have demonstrated an idiosyncrasy or hypersensitivity to promethazine.

Under no circumstances should promethazine be given by intra-arterial injection due to the likelihood of severe arteriospasm and the possibility of resultant gangrene

Promethazine HCl injection should not be given by the subcutaneous route; evidence of chemical irritation has been noted, and necrotic lesions have resulted on rare occasions following subcutaneous injection. The preferred parenteral route of administration is by deep intramuscular injection.

Syrup, Tablets and Suppositories: Phenergan Tablets and Suppositories are contraindicated for use in pediatric patients less than two years of age.

Phenergan Tablets and Suppositories are contraindicated in comatose states, and in individuals known to be hypersensitive or to have had an idiosyncratic reaction to promethazine or to other phenothiazines.

Antihistamines are contraindicated for use in the treatment of lower respiratory tract symptoms including asthma.

Additional information about Phenergan

Phenergan Indication: For the treatment of allergic disorders, itching, nausea and vomiting.
Mechanism Of Action: Like other H1-antagonists, promethazine competes with free histamine for binding at H1-receptor sites in the GI tract, uterus, large blood vessels, and bronchial muscle. The relief of nausea appears to be related to central anticholinergic actions and may implicate activity on the medullary chemoreceptor trigger zone.
Drug Interactions: Amphetamine Decreased anorexic effect, may increase pyschotic symptoms
Benzphetamine Decreased anorexic effect, may increase pyschotic symptoms
Bromocriptine The phenothiazine decreases the effect of bromocriptine
Dextroamphetamine Decreased anorexic effect, may increase pyschotic symptoms
Dexfenfluramine Decreased anorexic effect, may increase pyschotic symptoms
Diethylpropion Decreased anorexic effect, may increase pyschotic symptoms
Fenfluramine Decreased anorexic effect, may increase pyschotic symptoms
Guanethidine The agent decreases the effect of guanethidine
Mazindol Decreased anorexic effect, may increase pyschotic symptoms
Methamphetamine Decreased anorexic effect, may increase pyschotic symptoms
Metrizamide Increased risk of convulsions
Phendimetrazine Decreased anorexic effect, may increase pyschotic symptoms
Phenmetrazine Decreased anorexic effect, may increase pyschotic symptoms
Phentermine Decreased anorexic effect, may increase pyschotic symptoms
Phenylpropanolamine Decreased anorexic effect, may increase pyschotic symptoms
Galantamine Possible antagonism of action
Rivastigmine Possible antagonism of action
Donepezil Possible antagonism of action
Sparfloxacin Increased risk of cardiotoxicity and arrhythmias
Terfenadine Increased risk of cardiotoxicity and arrhythmias
Levofloxacin Increased risk of cardiotoxicity and arrhythmias
Gatifloxacin Increased risk of cardiotoxicity and arrhythmias
Grepafloxacin Increased risk of cardiotoxicity and arrhythmias
Cisapride Increased risk of cardiotoxicity and arrhythmias
Food Interactions: Not Available
Generic Name: Promethazine
Synonyms: Lilly 1516; Isopromethazine; Proazaimine; Proazamine; Promazinamide; Promethazin; Promethazine Hcl; Promethiazine; Promezathine; Prothazin; Prothazine
Drug Category: Anti-Allergic Agents; Antipruritics; Phenothiazine Derivatives
Drug Type: Small Molecule; Approved

Other Brand Names containing Promethazine: Allergan; Aprobit; Avomine; Dimapp; Diphergan; Diprazine; Diprozin; Dorme; Duplamin; Fargan; Fellozine; Fenazil; Fenergan; Fenetazina; Genphen; Hiberna; Histargan; Iergigan; Isophenergan; Lercigan; Lergigan; Mymethazine Fortis; Phargan; Phenargan; Phencen; Phenergan; Phenergan Fortis; Phensedyl; Pilpophen; Pipolphen; Procit; Prometasin; Prometazin; Prometh Fortis; Prometh Plain; Promethacon; Promethaine; Promethegan; Prorex; Protazine; Provigan; Pyrethia; Pyrethiazine; Remsed; Romergan; Synalgos; Tanidil; Thiergan; Valergine; Vallergine; Zipan-25;
Absorption: On average, 88% of a promethazine dose is absorbed after oral administration; however, the absolute bioavailability is only 25% because of first-pass clearance.
Toxicity (Overdose): Symptoms of overdose include mild depression of the central nervous system and cardiovascular system to profound hypotension, respiratory depression, unconsciousness, and sudden death. Other reported reactions include hyperreflexia, hypertonia, ataxia, athetosis, and extensor-plantar reflexes (Babinski reflex). LD₅₀=55mg/kg (I.V. in mice)
Protein Binding: 93%
Biotransformation: Hepatic
Half Life: 16-19 hours
Dosage Forms of Phenergan: Solution Intravenous
Tablet Oral
Cream Topical
Liquid Intramuscular
Syrup Oral
Chemical IUPAC Name: N,N-dimethyl-1-phenothiazin-10-ylpropan-2-amine
Chemical Formula: C17H20N2S
Promethazine on Wikipedia: https://en.wikipedia.org/wiki/Promethazine
Organisms Affected: Humans and other mammals