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| IUPAC_name = N,N-dimethyl- 1-(10H-phenothiazin-10-yl) propan-2-amine
| IUPAC_name = dimethyl[1-(10''H''-phenothiazin-10-yl)propan-2-yl]amine
| image = Promethazine.svg
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Revision as of 12:00, 21 December 2008

Promethazine
Clinical data
Pregnancy
category
  • AU: C
Routes of
administration
Oral, rectal, IV, IM, topical
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability88% absorbed but after first-pass metabolism reduced to 25% absolute bioavailability
Protein binding93%
MetabolismHepatic glucuronidation and sulfoxidation
Elimination half-life16-19 hours
ExcretionRenal and biliary
Identifiers
  • dimethyl[1-(10H-phenothiazin-10-yl)propan-2-yl]amine
CAS Number
PubChem CID
DrugBank
ChemSpider
CompTox Dashboard (EPA)
ECHA InfoCard100.000.445 Edit this at Wikidata
Chemical and physical data
FormulaC17H20N2S
Molar mass284.425 g/mol g·mol−1

Promethazine is a first-generation H1 receptor antagonist, antihistamine and antiemetic medication. It can also have strong sedative effects although it is rarely used specifically for this. It is a prescription drug in the United States, but is available over the counter in the United Kingdom, Switzerland, and many other countries (brand names Phenergan, Promethegan, Romergan, Fargan, Farganesse, Prothiazine, Avomine, Atosil, Receptozine, Lergigan).[1]

Chemically, promethazine hydrochloride (HCl) appears as a white to faint yellow crystaline powder which is practically odorless. Slow oxidation may occur upon prolonged exposure to air causing blue discoloration. Promethazine as the hydrochloride salt is freely soluble in water and somewhat soluble in alcohol.[2]

Indications

Contraindications

Mechanism of action

  • Promethazine is a phenothiazine derivative that competitively blocks histamine H1 receptors without blocking the secretion of histamine.[7]
  • It has sedative, anti-motion-sickness, anti-emetic, and anti-cholinergic effects

Side effects

Some common side effects include:

  • Blurred vision
  • Confusion in the elderly
  • Drowsiness, dizziness, fatigue, more rarely vertigo
  • Dry mouth
  • Seizures (extremely rare)
  • Neuroleptic malignant syndrome (extremely rare)
  • Respiratory depression in patients under age of 2 and in those with severely compromised pulmonal function
  • Constipation
  • Euphoria (very rare with high IV doses and/or coadministration with opioids/CNS depressants)
  • Restless legs [8]
  • Paresthesia

It is recommended that promethazine only be given through an existing intravenous set in a large vein and diluted to concentration no greater than 25mg per mL, not to exceed a rate of administration of 25mg a min. Serious complications including those listed above have resulted from improper parenteral administration, including those requiring surgical intervention and amputation.[9]

Laboratory examinations

All patients should have their blood pressure measured frequently. During long-term therapy, blood cell counts, liver function studies, EKG, and EEG are recommended. The intervals should be determined according to the risk profile of the patient. In high doses, promethazine can create auditory and visual hallucinations causing panic and intense fear.

Recreational use

Promethazine is sometimes used as a recreational drug in conjunction with codeine in prescription cough syrup. The syrup by itself contains 7% alcohol. The traditional mixture of Sprite and cough syrup with codeine, which is known as "purple drank", "Sizzurp", or "lean", is popularized in the rap world, especially in the Houston area.[10] It is also sometimes used to counteract nausea caused by illicit opioid use.

Politics

The U.S. Supreme Court has accepted a case involving promethazine that may influence product liability. A musician suffering from a migraine was administered Wyeth's Phenergan via IV push. The drug entered her arterial flow resulting in gangrene and subsequent amputation of her right arm below the elbow. A state jury awarded her $6 million in punitive damages. The case has been appealed to the Supreme Court on grounds of federal pre-emption and substantive due process.[11]

References

  1. ^ RxList: Promethazine
  2. ^ http://www.rxlist.com/cgi/generic/phenergan.htm RxList: Promethazine Description
  3. ^ a b c d e RxList Indications for Promethazine
  4. ^ British National Formulary (2003). "4.6 Drugs used in nausea and Vertigo - Vomiting of pregnancy". "BNF" (45 ed.). {{cite book}}: Unknown parameter |month= ignored (help)
  5. ^ "Letter from Wyeth Pharmaceuticals to practitioners regarding use of Phenergan in under twos" (PDF). FDA.
  6. ^ a b c d e f g RxList Contraindications
  7. ^ David J. McCann and Brett Roth, Toxicity, Antihistamine, eMedicine Toxicology, updated June 21, 2007
  8. ^ Cordingley Neurology
  9. ^ Baxter: Promethazine HCl Injection, USP Information
  10. ^ Peters RJ, Kelder SH, Markham CM, Yacoubian GS, Peters LA, Ellis A (2003). "Beliefs and social norms about codeine and promethazine hydrochloride cough syrup (CPHCS) onset and perceived addiction among urban Houstonian adolescents: an addiction trend in the city of lean". J Drug Educ. 33 (4): 415–25. doi:10.2190/NXJ6-U60J-XTY0-09MP. PMID 15237866.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Liptak, Adam (2008-09-18). "Drug Label, Maimed Patient and Crucial Test for Justices". The New York Times. Retrieved 2008-10-31.
  • "Promethazine". U.S. National Library of Medicine and National Institutes of Health.