Morphine belongs to the class of opioids. It is a strong painkiller (analgesic). It is a prescription and is subject to the Narcotics Act (BtMG).
Morphine was first extracted from the alkaloid opium in 1804 by FWA Sertüner. However, it took another 34 years to decipher the chemical structure. Sertüner then named the material after the Greek god of dreams and sleep Morpheus. This is how the name morphine originated. Later, however, the term morphine prevailed, it is still the common name today.
Since morphine is the prototype of an opioid, it is useful to explain its properties and effects to the entire group. Opioids are a group of potent analgesics. They are produced by the body itself in the form of endorphins, enkephalins and dynorphins and produced by the pharmaceutical industry as potent analgesics. They act on three different receptor types in the body, which mediate among other things an analgesic effect. The? Receptor (spoken: müh ), the? Receptor (pronounced delta ) and the? Receptor (pronounced kappa ). Depending on whether they act as activating on the receptors as the endogenous opioids, ie agonists, or whether they act in opposition to the endogenous opioids, ie are antagonists and thus inhibit the receptors, the opioids are divided into different groups assigned. Here is the somewhat simplified scheme:
1. pure agonists: act on all three receptors agonistic, so they activate these receptors. Depending on the substance, the strength of the effect differs at the different receptors. Among others, this group includes
2. partial agonists / antagonists: have hardly any activating effect on the α receptor, but more or less strongly activate on the other receptors. This subclass includes:
pure antagonists counteract the opioids at all receptors. So they (if they are present in sufficiently large amounts and can bind to the receptors) raise their effect. The most important representative of this group is naloxone. This substance is used in the case of poisoning with opioids ( opioid intoxication ) as an antidote (antidote) and can thus be life-saving.
Opioids can be supplied in a variety of ways. As a tablet ( peroral ), intravenously (ie injected into a vein), as a suppository ( rectal ), as a patch ( transdermal ) or as a drop.
Opioids / morphine have great dependence potential. Depending on the type of intake and which substance is administered, this potential is stronger or weaker. The greatest dependence potential possesses, for example, the intravenous supply of heroin ( derivative of morphine ), since heorin floats extremely fast in the brain and thus brings within a short time after ingestion the "desired" intoxication.
Withdrawal symptoms include sweating, pain, diarrhea, vomiting and circulatory failure.
Tolerance development occurs with prolonged intake of an opioid. As a result, many of the effects are attenuated, it develops a habituation. First and foremost, it is the analgesic (that is, the only desired) effect that subsides. Constipation (constipation) and pupil constriction ( miosis ) are the least affected by the development of tolerance, so they are still unrestricted even after a prolonged intake of opioids.
An overdose of opioids is usually accompanied by a typical symptom triad:
Therapeutically, an opioid antagonist must be given as soon as possible in order to best release the effects of the poison. As such an antidote naloxone is usually used. It is important to note that naloxone has a relatively short half-life of one hour, whereas most opioids work much longer in the body, so naloxone needs to be re-injected at regular intervals.
The different opioids have very different strong analgesic effect. Morphine was given potency 1, so that the analgesic potency of the other opioids is measured to that of morphine.
The strongest analgesic effect has sufentanil. It has a potency of 1000 and is therefore 1000 times more pain-relieving than morphine (which means that it could be administered in 1000-fold lower dose than morphine to achieve the same analgesic effect). In order to name a few more strengths here - in descending pain relief - a small listing follows:
Sufentanil <fentanyl <buprenorphine <morphine <piritramide <pentazocine <codeine <tramadol <tilidine.
When administered as a tablet, morphine is well absorbed (taken from the gastrointestinal tract into the bloodstream), but it undergoes a pronounced first-pass mechanism (since the blood into which morphine has been taken from the gastrointestinal tract is the liver first flows through and here a large part of the morphine is already metabolized, relatively little active ingredient in the organism, the bioavailability of morphine is therefore low). However, this is already taken into account when administered in tablet form, so that the dose in the tablet is so high that it still promises sufficient effect even after the degradation in the liver.
Morphine has a half-life of about 2-4 hours.