Codeine
Systematic ( IUPAC) name
7,8-didehydro-4,5-epoxy- 3-methoxy-17-methylmorphinan-6-ol
Identifiers
CAS number	76-57-3
ATC code	R05 DA04
PubChem	5284371
DrugBank	APRD00120
Chemical data
Formula	C18 H21 N O3
Mol. mass	299.364 g/mol
Pharmacokinetic data
Bioavailability	~90% Oral
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status	Schedule I ( CA ) Class B ( UK ) Schedule II ( US )
Routes	oral, intra-rectally, SC, IM

Codeine ( INN) or methylmorphine is an opiate used for its analgesic, antitussive and antidiarrheal properties. It is marketed as the salts codeine sulfate and codeine phosphate. Codeine hydrochloride is more commonly marketed in continental Europe and other regions.

Codeine is an alkaloid found in opium in concentrations ranging from 0.3 to 3.0 percent. While codeine can be extracted from opium, most codeine is synthesized from morphine through the process of O- methylation.

Indications

Approved indications for codeine include:

• Cough, though its efficacy in low dose over the counter formulations has been disputed. ^[1]
• Diarrhea
• Moderate to severe pain
• Irritable bowel syndrome

Codeine is sometimes marketed in combination preparations with paracetamol (acetaminophen) as co-codamol (best known in North America as Tylenol 3), with aspirin as co-codaprin or with ibuprofen. These combinations provide greater pain relief than either agent alone (drug synergy; see synergy). Codeine is also commonly compounded with other pain killers or muscle relaxers such as Fioricet with Codeine, Soma Compound/Codeine, etc.

Controlled substance

In Australia, New Zealand and Canada, codeine is regulated; however, it is available without prescription in combination preparations from licensed pharmacists in doses up to 8 mg/tablet in Canada, and 15 mg/tablet in Australia and New Zealand.

In Canada, codeine can only be sold over the counter in combination with 2 or more ingredients, which has resulted in the prevalence of AC&C ( aspirin, codeine, and caffeine), and similar combinations using acetaminophen ( paracetamol) rather than aspirin. Caffeine, being a stimulant, tends to offset the sedative effects of codeine. It also can increase the effectiveness and absorption rate of analgesics in some circumstances. ^[2]

In Hong Kong, codeine is regulated under Schedule 1 of Hong Kong's Chapter 134 Dangerous Drugs Ordinance. It can only be used legally by health professionals and for university research purposes. The substance can be given by pharmacists under a prescription. Anyone who supplies the substance without prescription can be fined $10000( HKD). The penalty for trafficking or manufacturing the substance is a $5,000,000 (HKD) fine and life imprisonment. Possession of the substance for consumption without license from the Department of Health is illegal with a $1,000,000 (HKD) fine and/or 7 years of jail time.

In the United Kingdom, codeine is regulated by the Misuse of Drugs Act 1971; it is a Class B drug, except for concentrations of less than 12.8 mg when combined with paracetamol or ibuprofen, which are available in many over the counter preparations.

In the United States, codeine is regulated by the Controlled Substances Act. It is a Schedule II controlled substance for pain-relief products containing codeine alone. In combination with aspirin or acetaminophen ( paracetamol/Tylenol) it is listed as Schedule III or V, depending on formula. Preparations containing small amounts of codeine are Schedule V in the US, and may be dispensed without a prescription; however, very few pharmacists will sell these preparations without a prescription. Furthermore, many states have their own laws that do require a prescription for Schedule V drugs.

Codeine is also available outside the United States as an over-the-counter drug in liquid cough-relief formulations. Internationally, codeine is a Schedule II drug under the Single Convention on Narcotic Drugs. ^[3]

Pharmacology

Main article: opioid receptor

Adverse effects

Common adverse drug reactions associated with the use of codeine include itching, nausea, vomiting, drowsiness, dry mouth, miosis, orthostatic hypotension, urinary retention and constipation. ^[4]

Tolerance to many of the effects of codeine develops with prolonged use, including therapeutic effects. The rate at which this occurs develops at different rates for different effects, with tolerance to the constipation-inducing effects developing particularly slowly for instance.

A potentially serious adverse drug reaction, as with other opioids, is respiratory depression. This depression is dose-related and is the mechanism for the potentially fatal consequences of overdose.

Another side effect commonly noticed is the lack of sexual drive. ^{[citation needed]}

Codeine has also been known to interact negatively with some psychiatric medications such as reboxetine and venlafaxine. ^{[citation needed]}

Some people may also have an allergic reaction to codeine, which may cause severe illness or even death.

Footnotes

1. ^ Schroeder K, Fahey T (2001). "Over-the-counter medications for acute cough in children and adults in ambulatory settings.". Cochrane Database Syst Rev: CD001831. DOI: 10.1002/14651858.CD001831. PMID 15495019.  
2. ^ Headache Triggers: Caffeine. WebMD (June 2004). Retrieved on 2007-03-23.
3. ^ International Narcotics Control Board. List of Narcotic Drugs under International Control (PDF). Retrieved on 2006-05-24.
4. ^ Australian Medicines Handbook (2004). in Rossi S: Australian Medicines Handbook. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2.  

External links

• Codeine Addiction Help Forum

• Links to external chemical sources

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