Product Description
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid.
Morphine is the most abundant alkaloid found in opium, the dried sap (latex) derived from shallowly slicing the unripe seedpods of the opium, or common and/or edible, poppy, Papaver somniferum.
In clinical medicine, morphine is regarded as the gold standard, or benchmark, of analgesics used to relieve severe or agonizing pain and suffering. Like other opioids, such as oxycodone, hydromorphone, and diacetylmorphine (heroin), morphine acts directly on the central nervous system (CNS) to relieve pain. Unlike many other opioids, morphine is an opiate and a natural product. Morphine has a high potential for addiction; tolerance and psychological dependence develop rapidly, although physiological dependence may take several months to develop.
Medical uses:
Morphine is primarily used to treat both acute and chronic severe and agonizing pain.It is also used for pain due to myocardial infarction (heart attack) and for labor pains. There are however concerns that morphine may increase mortality in the setting of non ST elevation myocardial infarction.Morphine has also traditionally been used in the treatment of the acute pulmonary edema. Its duration of analgesia is about 3-4 hours when administered via the intravenous, subcutaneous, or intramuscular route and 3-6 hours when given by mouth.Morphine is also used in slow release formulations for opiate substitution therapy (OST) in Austria, Bulgaria, and Slovenia, for addicts who cannot tolerate the side effects of using either methadone or buprenorphine, or for addicts who are "not held" by buprenorphine or methadone. It is used for OST in many parts of Europe although on a limited basis.
Adverse effects:
Constipation:
Like loperamide and other opioids, morphine acts on the myenteric plexus in the intestinal tract, reducing gut motility, causing constipation. The gastrointestinal effects of morphine are mediated primarily by μ-opioid receptors in the bowel. By inhibiting gastric emptying and reducing propulsive peristalsis of the intestine, morphine decreases the rate of intestinal transit. Reduction in gut secretion and increased intestinal fluid absorption also contribute to the constipating effect.
Addiction:
Morphine is a potentially highly addictive substance - one of the most addictive known to man. It can cause psychological dependence and physical dependence as well as tolerance, with an addiction potential identical to that of heroin. In the presence of pain and the other disorders for which morphine is indicated, a combination of psychological and physiological factors tend to prevent true addiction from developing, although severe physical dependence and tolerance will develop with protracted opioid therapy.
Tolerance:
Tolerance to the analgesic effects of morphine is fairly rapid. There are several hypotheses about how tolerance develops, including opioid receptor phosphorylation (which would change the receptor conformation), functional decoupling of receptors from G-proteins (leading to receptor desensitization),
Withdrawal:
Cessation of dosing with morphine creates the prototypical opioid withdrawal syndrome, which, unlike that of barbiturates, benzodiazepines, alcohol, or sedative-hypnotics, is not fatal by itself in neurologically healthy patients without heart or lung problems; it is in theory self-limiting in length and overall impact in that a rapid increase in metabolism and other bodily processes takes place, including shedding and replacement of the cells of many organs.
Acute morphine along with and other opioid withdrawal proceeds through a number of stages. Other opioids differ in the intensity and length of each, and weak opioids and mixed agonist-antagonists may have acute withdrawal syndromes that do not reach the highest level. As commonly cited they are:
Stage I: Six to fourteen hours after last dose: Drug craving, anxiety, irritability, perspiration, and mild to moderate dysphoria.
Stage II: Fourteen to eighteen hours after last dose: Yawning, heavy perspiration, mild depression lacrimation, crying, running nose, dysphoria, also intensification of the above symptoms. "yen sleep" (a waking trance-like state)
Stage III: Sixteen to twenty-four hours after last dose: Rhinorrhea (runny nose) and increase in other of the above, dilated pupils, piloerection (gooseflesh), muscle twitches, hot flashes, cold flashes, aching bones and muscles, loss of appetite and the beginning of intestinal cramping.
Stage IV: Twenty-four to thirty-six hours after last dose: Increase in all of the above including severe cramping and involuntary leg movements ("kicking the habit"), loose stool, insomnia, elevation of blood pressure, moderate elevation in body temperature, increase in frequency of breathing and tidal volume, tachycardia (elevated pulse), restlessness, nausea
Stage V: Thirty-six to seventy-two hours after last dose: Increase in the above, fetal position, vomiting, free and frequent liquid diarrhea, which sometimes can accelerate the time of passage of food from mouth to out of system to an hour or less, involuntary ejaculation, which is often painful, saturation of bedding materials with bodily fluids, weight loss of two to five kilos per 24 hours, increased white cell count and other blood changes.
Stage VI: After completion of above: Recovery of appetite ("the chucks"), and normal bowel function, beginning of transition to post-acute and chronic symptoms that are mainly psychological but that may also include increased sensitivity to pain, hypertension, colitis or other gastrointestinal afflictions related to motility, and problems with weight control in either direction.
The withdrawal symptoms associated with morphine addiction are usually experienced shortly before the time of the next scheduled dose, sometimes within as early as a few hours (usually between 6–12 hours) after the last administration. Early symptoms include watery eyes, insomnia, diarrhea, runny nose, yawning, dysphoria, sweating and in some cases a strong drug craving. Severe headache, restlessness, irritability, loss of appetite, body aches, severe abdominal pain, nausea and vomiting, tremors, and even stronger and more intense drug craving appear as the syndrome progresses. Severe depression and vomiting are very common. During the acute withdrawal period systolic and diastolic blood pressure increase, usually beyond pre-morphine levels, and heart rate increases, which have potential to cause a heart attack, blood clot, or stroke.
The psychological dependence associated with morphine addiction is complex and protracted. Long after the physical need for morphine has passed, the addict will usually continue to think and talk about the use of morphine (or other drugs) and feel strange or overwhelmed coping with daily activities without being under the influence of morphine. Psychological withdrawal from morphine is a very long and painful process. Addicts often suffer severe depression, anxiety, insomnia, mood swings, amnesia (forgetfulness), low self-esteem, confusion, paranoia, and other psychological disorders. Without intervention, the syndrome will run its course, and most of the overt physical symptoms will disappear within 7 to 10 days including psychological dependence. There is a high probability that relapse will occur after morphine withdrawal when neither the physical environment nor the behavioral motivators that contributed to the abuse have been altered. Testimony to morphine's addictive and reinforcing nature is its relapse rate. Abusers of morphine (and heroin) have one of the highest relapse rates among all drug users, ranging up to 98 per cent in the estimation of some clinicians, neuropharmacologists, mental health/AODA professionals and other medical experts.
Overdose:
A large overdose can cause asphyxia and death by respiratory depression if the person does not receive medical attention immediately.Overdose treatment includes the administration of naloxone. The latter completely reverses morphine's effects, but precipitates immediate onset of withdrawal in opiate-addicted subjects. Multiple doses may be needed.
The minimum lethal dose is 200 mg but in case of hypersensitivity 60 mg can bring sudden death. In case of drug addiction, 2-3 g/day can be tolerated.
Effects on human performance:
In terms of cognitive abilities, one study has shown that morphine may have a negative impact on anterograde and retrograde memory, but these effects are minimal and are transient. Overall, it seems that acute doses of opioids in non-tolerant subjects produce minor effects in some sensory and motor abilities, and perhaps also in attention and cognition. It is likely that the effects of morphine will be more pronounced in opioid-naive subjects than chronic opioid users.
In chronic opioid users, such as those on Chronic Opioid Analgesic Therapy (COAT) for managing severe, chronic pain, behavioural testing has shown normal functioning on perception, cognition, coordination and behaviour in most cases. . COAT patients showed rapid completion of tasks that require speed of responding for successful performance (e.g., Rey Complex Figure Test) but made more errors than controls. COAT patients showed no deficits in visual-spatial perception and organization (as shown in the WAIS-R Block Design Test) but did show impaired immediate and short-term visual memory (as shown on the Rey Complex Figure Test – Recall). These patients showed no impairments in higher order cognitive abilities (i.e., Planning). COAT patients appeared to have difficulty following instructions and showed a propensity toward impulsive behaviour, yet this did not reach statistical significance. It is important to note that this study reveals that COAT patients have no domain-specific deficits, which supports the notion that chronic opioid use has minor effects on psychomotor, cognitive, or neuropsychological functioning.
It is difficult to study the performance effects of morphine without considering why a person is taking morphine. Opioid-naive subjects are volunteers in a pain-free state. However, most chronic-users of morphine use it to manage pain. Pain is a stressor and so it can confound performance results, especially on tests that require a large degree of concentration. Pain is also variable, and will vary over time and from person to person. It is unclear to what extent the stress of pain may cause impairments, and it is also unclear whether morphine is potentiating or attenuating these impairments.