What is morphine? Morphine (MOP), an opioid receptor agonist, is 4% – 21% in opium, with an average of about 10%. The name of IUPAC is 7,8-didehydro-4,5-epoxy-17-methyl-morphinan-3,6-diol. The molecular formula is C17H19NO3 and the molecular weight is 285.3.
In 1806, the German chemist zeltina first isolated it from opium and named it morphine after the Greek dream God Morpheus. Its derivative morphine hydrochloride is a commonly used anesthetic in clinic. It has strong analgesic effect, and its analgesic effect has good selectivity. It is mostly used for severe pain caused by trauma, operation and burn, as well as angina pectoris caused by myocardial infarction. It can also be used as analgesic, antitussive and antidiarrheal agents; The diacetate of morphine is also known as heroin. But its biggest disadvantage is addiction. This makes long-term smokers have a serious dependence on morphine both physically and psychologically, resulting in serious toxicosis, which does great harm to themselves and society.
Morphine and its derivatives are the main drugs for relieving severe pain in clinic and the most powerful analgesics in the world. The analgesic effect of pethidine is weaker than that of morphine, and the analgesic time is only 2.5 ~ 3.5H. The metabolite norpethidine in the body is T1 / 213 ~ 14h. Repeated use is easy to accumulate and produce central nervous excitation, and injection can cause local inflammation and tissue induration. Therefore, it is not suitable for patients who need long-term medication, but it is recommended to use it for patients with severe pain.
It is commonly used as its hydrochloride or sulfate, belonging to opioid alkaloids and opioid receptor agonists. One of the main components of opium, containing 6% – 15%. It was first isolated from opium by stunell in 1806. Colorless columnar crystal, MP. 253-254 ℃. Soluble in hot water, ethanol, ether and chloroform; Insoluble in ammonia and benzene; Soluble in alkaline or acid water. It has excellent analgesic effect. It is the earliest analgesic used by human beings. It also has strong anesthetic effect.
Laurent determined that the molecular formula of morphine was c17h19o3n by elemental analysis in 1847, and the structure of morphine was not basically determined until 1925; Various total synthesis methods appeared around 1950.
(1) By simulating the action of endogenous anti pain substance enkephalin, it can stimulate central nervous opioid receptor and produce strong analgesic effect. It is effective for all pain, and its effect on persistent dull pain is stronger than intermittent sharp pain and visceral colic.
(2) It has obvious sedative effect while analgesia, and improves the tension of pain patients.
(3) It can inhibit the respiratory center and reduce the sensitivity of the respiratory center to carbon dioxide. The degree of inhibition to the respiratory center is dose-dependent. Excessive dose can lead to respiratory failure and death.
(4) It can inhibit cough center and produce antitussive effect.
(5) It can excite smooth muscle, increase the tension of intestinal smooth muscle and lead to constipation, and increase the tension of smooth muscle of bile duct, ureter and bronchus.
(6) It can promote the release of endogenous histamine, resulting in peripheral vasodilation, decreased blood pressure, cerebral vasodilation and increased intracranial pressure.
(7) It has the functions of antiemetic and mydriasis. The drug is absorbed from the gastrointestinal tract after oral administration, and the analgesic effect lasts for 4 ~ 6 hours. The absorption is rapid after subcutaneous and intramuscular injection. 60% can be absorbed 30 minutes after subcutaneous injection, and the plasma protein binding rate is 26% ~ 36%. After absorption, it can be distributed in lung, liver, spleen, kidney and other tissues, and can pass through the placenta, only a small amount through the blood-brain barrier, but it can produce analgesic effect. The drug is mainly metabolized through the liver, 60% ~ 70% of which is combined with glucuronic acid in the liver, 10% demethylated to demethylmorphine and 20% free. Mainly excreted by kidney, a small amount excreted by bile and milk. The clearance half-life of ordinary tablets is 1.7 ~ 3 hours. The peak effect of sustained-release tablets and controlled-release tablets is long, 2 ~ 3 hours, the peak concentration is low, the fluctuation of blood concentration is small when reaching the steady state, and the clearance half-life is 3.5 ~ 5 hours.