Meptazinol is a drug that belongs to the group of active substances known as opioid analgesics. The drug is used as part of the therapy of various pain conditions. Unlike most other types of these active substances, meptazinol is not subject to the Narcotics Act when administered by injection. Meptazinol is particularly commonly used to treat obstetric pain.
What is meptazinol?
The active ingredient meptazinol is primarily used to treat pain. The drug is used particularly frequently in the context of childbirth. The active ingredient meptazinol is available on the market under the trade name Meptid. The manufacturer of the product is Riemser Arzneimittel. Meptazinol is an opioid analgesic that is suitable for moderate to severe pain. The pain treated may be due to a variety of causes. Together with the active ingredients nalbuphine and tramadol, meptazinol is the only opioid analgesic that can be injected and at the same time is not subject to narcotics legislation. The so-called analgesic potency of the substance meptazinol is 0.1 times that of morphine. For this reason, there is virtually no development of dependence. In pharmacy, meptazinol hydrochloride is used in most cases. There are different chemical designations for this substance. Basically, the active ingredient is present as an aromatic hydrocarbon compound. At room temperature, meptazinol appears in the form of a solid. The melting point of the active ingredient is 128 to 132 degrees Celsius. If meptazinol is present as a hydrochloride, the melting point increases to approximately 183 to 187 degrees Celsius. In addition, there are two different stereoisomers of the active ingredient meptazinol, because the corresponding molecule has a so-called stereocenter. This is divided into the R-enantiomer and the mirror-image S-enantiomer. In those preparations that are commercially available, a so-called 1:1 racemate is usually present in meptazinol.
Pharmacologic action
The µ1 opioid receptor plays a crucial role in the analgesic effect. Meptazinol binds to this receptor as a partial agonist. There is only a slight binding to the µ2 receptor, which can induce respiratory depression. For this reason, the risk of respiratory depression during therapy with meptazinol is only slight. Unlike other commonly used analgesics, central cholinergic mechanisms support the analgesic effect of meptazinol. Numerous processes play a role in the synthesis of the active ingredient meptazinol. The starting materials for the production of meptazinol are 2-(3-methoxyphenyl)butyronitrile and 4-iodobutyric acid ethyl ester. The two substances are transformed into other compounds in the course of chemical processes and are cleaved several times. As a result of the last reaction of the substances, the active ingredient meptazinol is formed.
Medical application and use
The active substance meptazinol is used primarily for the treatment of pain. The drug is particularly frequently used in the context of childbirth. The aim of administration here is to make labor pain more bearable. Unlike other drugs, meptazinol has a better side-effect profile and is increasingly replacing the active ingredient pethidine in delivery rooms. The greatest advantage of meptazinol is that the substance is less likely to cause respiratory depression in newborn babies. If respiratory depression does occur, it is usually less severe. In addition to the treatment of labor pain, the active ingredient meptazinol has a number of other uses. For example, it is used as a postoperative analgesic if the existing pain is only mild to moderate. The drug is also used as a basic analgesic in opioid-assisted anesthesia. In addition, meptazinol is also used to some extent for acute and traumatic pain, for example in emergency medicine. The reason for this is that the probability of the onset of respiratory depression is greatly reduced. In addition, the active ingredient meptazinol is used as an analgesic for pain therapy in elderly patients. Meptazinol is also administered in the context of pain situations associated with severe blood loss. In this case, the adrenergic and slightly circulatory stimulating effect is exploited.It also benefits from its antiarrhythmic effect. Since the impairment of vigilance (wakefulness) is low and proteins bind only minimally, it is preferably used as an analgesic for moderately severe pain, especially in very old patients. In principle, the physician decides on the duration of use of the active substance. It is usually based on the cause of the pain as well as the type of disease. Meptazinol in liquid form is injected either into the muscle or slowly into the vein.
Risks and side effects
Therapy with the active ingredient meptazinol can lead to a variety of unwanted side effects. The most common side effects include vomiting and nausea. Fatigue also often occurs during treatment. This can progress to drowsiness and dizziness. In addition, cephalgia (headache) and gastrointestinal changes are possible. Affected patients often complain of abdominal pain and diarrhea. If the drug meptazinol is administered, various interactions with other substances must be taken into account. For example, drugs with a liver enzyme-inducing effect are able to significantly minimize the effect of meptazinol. In some cases, therapy with meptazinol is not suitable. This is particularly true during pregnancy, where there is a risk of respiratory depression in the child. The birth process, on the other hand, is an exception.
