Dihydrocodeine is an opioid that has analgesic and antitussive effects. It has an analgesic potency of 0.2 and is mainly used to treat unproductive irritable coughs.
Dihydrocodeine is a drug from the group of opioids that is used both analgesically (to relieve pain) and to relieve irritable coughs. The analgesic potency of dihydrocodeine is 0.2. The analgesic potency is a measure of the analgesic effect of a drug, usually an opioid.
Morphine with an analgesic potency of 1 is used as the reference substance. So morphine has five times more pain relieving effects than dihydrocodeine. In order to achieve the same analgesic effect that would be achieved with one milligram of morphine, five milligrams of dihydrocodeine would have to be administered.
Dihydrocodeine is based on a phenanthrene structure. Dihydrocodeine is a white to yellowish-white solid. The chemical formula of the substance is C18H23NO3, the molecular mass is 301.4 g / mol. Dihydrocodeine is a derivative of morphine and is produced semi-synthetically.
Dihydrocodeine is chemically derived from the codeine by adding hydrogen to it twice. Dihydrocodeine is poorly soluble in water. In finished medicinal products it is mostly used as dihydrocodeine hydrogen tartrate. This salt of dihydrocodeine can be dissolved in water in a ratio of 1: 4.5.
In Germany, dihydrocodeine is considered a marketable and prescription drug. It is listed in Appendix 3 of the Narcotics Act. If codeine is contained in a drug with a content of less than 2.5% or less than 100 mg / unit, this is subject to a prescription, but a narcotic prescription is not required. The documentation requirement required by the Narcotics Act is also not required in this case.
However, if dihydrocodeine is prescribed to people who are dependent on alcohol or narcotics, a narcotic prescription is essential to prevent abuse.
Dihydrocodeine is administered orally in the form of tablets, capsules, prolonged-release tablets and drops. After oral administration, it is quickly absorbed in the intestine. The first pass effect is very pronounced with dihydrocodeine, which means that there is only a systemic bioavailability of twelve to 34%.
The maximum plasma concentration of dihydrocodeine is reached after 1.6 to 1.8 hours. It is able to cross the blood-brain barrier and the placental barrier. Dihydrocodeine also gets into breast milk. The metabolism of dihydrocodeine takes place in the liver (hepatic). Some of the substance is excreted unchanged in the urine. Dihydrocodeine has a plasma half-life of about four hours on average.
The effect of dihydrocodeine is based on the binding of the substance to the opioid receptors. Through this bond, it dampens the cough center and pain perception. The antitussive effect starts about fifteen to 30 minutes after oral administration.
Dihydrocodeine is mainly used to suppress unproductive irritable cough. However, it is also used as an analgesic for moderate pain. It can also be used for heroin substitution; however, this application is only permitted in justified exceptional cases. Methadone or levomethadone are normally used for heroin substitution.
In analgesic terms, dihydrocodeine is mainly used to treat joint pain, phantom pain, neuropathies and postoperative pain. The analgesic potency of dihydrocodeine is twice as high as the analgesic potency of codeine.
The undesirable drug effects of dihydrocodeine include sedation, euphoria, disorders of the gastrointestinal tract (especially constipation, nausea and vomiting), tiredness, dizziness, sleep disorders, allergic skin reactions such as itching and rash, headache, hypersensitivity, visual disturbances and pupillary constriction (miosis) and edema.
Contraction of the ureter and an inhibition of the micturition reflex can also be caused by the contraction of the smooth muscles caused by dihydrocodeine.
Dihydrocodeine must not be used if there is hypersensitivity to dihydrocodeine. Furthermore, it must not be used in the presence of a coma, bronchial asthma, respiratory insufficiency, chronic cough, liver dysfunction, pancreatitis, pregnancy or breastfeeding.
MAOIs should not be used at the same time as dihydrocodeine.In addition, drugs containing dihydrocodeine must not be given to children under four years of age.
As with all opioids, there is also a risk of dihydrocodeine being misused as an intoxicant. Persistent use can lead to the development of tolerance and dependence.