Generality
Morphine is a natural alkaloid extracted from opium, obtained by drying the milky liquid that comes out of the immature capsule of Papaver somniferum after having engraved it.
Morphine is used as a therapeutic aid in the treatment of chronic pain - deep, of medium-high intensity, such as the neoplastic pain in the terminal phase. In this regard it is interesting to note that morphine abolishes pain intended as suffering, but not its perception. Often the subject remains aware of the pain stimulus, perceives it but does not care, detaches it and has no difficulty tolerating it.
Morphine is available in pharmaceutical formulations suitable for oral and parenteral administration.
Examples of medicinal specialties containing morphine
- Kapanol ®
- MS Contin ®
- Oramorph ®
- Skenan ®
- Twice ®
Therapeutic indications
The use of morphine is indicated for the treatment of moderate to severe pain and resistant to other painkillers.
In particular, morphine is used for the treatment of pain associated with neoplastic diseases (tumors) and myocardial infarction, and for the treatment of post-operative pain.
Warnings
The use of morphine - especially for long periods - can cause tolerance and dependence. For this reason it is essential to take this drug carefully following all the indications provided by the doctor, both as regards the amount of morphine to be taken, both as regards the frequency of administration and the duration of treatment.
Before starting treatment with morphine, it is advisable to inform your doctor if you suffer from hypothyroidism, since - in this case - it may be necessary to reduce the dose of morphine administered.
Furthermore, before starting morphine therapy, you must inform your doctor if:
- One suffers from hypotension;
- You suffer from organic brain diseases;
- You suffer from myxedema and hyperthyroidism;
- You suffer from toxic psychosis;
- You are suffering from pancreatitis or gall bladder disorders;
- You have biliary colic;
- You suffer from inflammatory or obstructive intestinal diseases;
- You are suffering from epilepsy or convulsive disorders;
- You suffer from fainting and / or mental confusion;
- You suffer from prostatic hypertrophy;
- You are suffering from chronic lung diseases and / or obstructive airway diseases;
- You suffer from reduced adrenal function;
- One is suffering from chronic nephropathy;
- You suffer - or have suffered in the past - from alcoholism and / or drug addiction.
Alcohol intake during morphine therapy should be avoided, as there may be an increase in the side effects induced by the same drug.
Morphine causes sedation and drowsiness, therefore it may alter the ability to drive and / or use machinery. Should these side effects occur, these activities should be avoided.
Finally, for those who carry out sporting activities, the use of the drug without therapeutic necessity constitutes doping and in any case can determine positivity to anti-doping tests even when taken for therapeutic purposes.
Interactions
Concomitant administration of morphine and MAOIs (monoamine oxidase inhibitors) should be avoided, as it can cause hypotension and respiratory depression.
The simultaneous intake of morphine and naltrexone should not be carried out, since the latter can counteract the pain-relieving action of morphine.
The co-administration of morphine and the following drugs, on the other hand, must be done with extreme caution:
- Rifampicin, as there may be a decrease in the plasma concentration of morphine;
- Cimetidine and other drugs capable of inhibiting cytochrome P450, since these drugs can cause an increase in the plasma concentration of morphine;
- Barbiturates ;
- Benzodiazepines and anxiolytics, since there is an increased risk of onset of respiratory depression which can also be fatal;
- Other opioid analgesics, such as codeine, dihydrocodeine, fentanyl, oxycodone, tramadol, etc .;
- Morphine-like and morphinic antitussive drugs (respectively, such as dextromethorphan and codeine);
- Drugs that depress the central nervous system, such as sedative-hypnotics, anxiolytics, antidepressants, antihistamines and muscle relaxants, as there may be an increased risk of impaired alertness;
- Oral anticoagulants, since morphine can increase its effects;
- Diuretics, because morphine can decrease its activity.
In any case, it is advisable to inform your doctor if you are taking - or have recently been - any type of medication, including medicines without a prescription and herbal and homeopathic products.
Side effects
Morphine can cause various types of side effects, although not all patients experience them. The type of adverse effects and the intensity with which they occur depend on each individual's sensitivity to the drug.
Generality
The most dangerous side effect of morphine is its powerful depressive action on the center of the breath, which in case of acute intoxication can lead to coma and death from respiratory paralysis. For this reason morphine is contraindicated for asthmatic subjects and for those suffering from emphysema or other pathologies characterized by reduced respiratory efficiency.
Other side effects include nausea, itching, miosis (point-like pupil) and constipation (a morphine derivative, called loperamide, is used as an antidiarrheal).
Particularly dangerous are the repercussions on the psyche of the individual, given the ability of morphine to induce deficiency states or abstinence (when the intake is abruptly interrupted, opposite effects arise, such as diarrhea, malaise, depression, increased body temperature and hyperhidrosis) . .
The need to take on morphine all the time, at any cost and, as we shall see, at ever increasing doses, has devastating effects on the sociality and mental health of the drug addict.
The chronic intake of morphine causes addiction and, as such, is accompanied by a resistance to its therapeutic effects. To obviate this phenomenon of "tolerance" and maintain the same action, it is therefore necessary to gradually increase the dose (this is why the patches based on a derivative of morphine, fentanyl, destined for terminally ill patients are periodically replaced with others with greater release). ).
Finally, the actual physical dependence on the alkaloid should not be underestimated; when the assumption is interrupted abruptly, the patient complains in fact a strong lack of the euphoric state produced by it.
The main side effects that may occur during the course of morphine therapy are listed below.
Lung and respiratory tract disorders
Morphine treatment can cause:
- Respiratory depression;
- Partial atelectasis (especially in patients with pre-existing bronchopulmonary diseases);
- Respiratory arrest.
Nervous system disorders
Morphine therapy can promote the onset of:
- Headache;
- Sedation;
- Drowsiness;
- Increase in intracranial pressure;
- Mental dullness;
- Syncope.
Psychiatric disorders
During treatment with morphine may occur:
- Insomnia;
- agitation;
- Excitement;
- Irritability;
- Euphoria or dysphoria;
- Depression.
Cardiovascular disorders
Morphine-based therapy can cause:
- Circulatory depression;
- Orthostatic hypotension;
- Peripheral vasodilation;
- Cardiovascular collapse.
Gastrointestinal disorders
Morphine treatment can cause:
- Nausea;
- He retched;
- Epigastric discomfort;
- Decrease in intestinal peristalsis.
Skin and subcutaneous tissue disorders
Morphine therapy can promote the onset of:
- Generalized redness of the skin (including that of the face);
- Urticaria;
- Itch;
- Skin eruptions;
- Increased sweating.
Tolerance and dependence
Morphine can cause tolerance and dependence. Therefore, failure to take morphine can trigger a withdrawal syndrome that manifests with symptoms such as:
- Chills of cold;
- Hypertension;
- mydriasis;
- Diarrhea;
- Hyperalgesia.
Other side effects
Other side effects that may occur during treatment with morphine are:
- Urination difficulties;
- oliguria;
- Spasm of the sphincter of Oddi;
- Biliary colic;
- Miosi;
- Asthenia;
- Dizziness;
- Decreased levels of luteinizing hormone, follicle stimulating hormone and testosterone;
- Decreased blood levels of corticotropin;
- Increased levels of antidiuretic hormone and prolactin.
Overdose
In the event of excessive doses of morphine, severe respiratory and circulatory depressions can occur and the state of consciousness is reduced to respiratory arrest, collapse and coma.
Other symptoms of morphine overdose are:
- Hypothermia;
- Extreme miosis;
- Skeletal muscle flaccidity.
In the case of morphine overdosage, the quintessential antidote is naloxone which must be administered intravenously.
However, if you suspect that you have taken excessive doses of morphine, you must inform your doctor immediately and go to the nearest hospital.
Action mechanism
Morphine is a selective opioid μ receptor agonist. These receptors are located along the pain pathways of our body and their task is precisely to modulate the neurotransmission of pain. More in detail, when these receptors are stimulated, analgesia is induced.
Therefore, morphine - as a selective agonist of the aforementioned receptors - is able to activate them and to exercise its powerful pain-relieving action.
The ability of morphine to interact with μ-type opioid receptors also explains the state of euphoria that arises following its intake. However, the excitement is transient and after a few minutes depressive and narcotic symptoms take over (the name morphine derives from Morfeo, the Greek god of sleep and dreams).
Method of use and dosage
Morphine is available for oral administration (in the form of oral solution, syrup, tablets, hard capsules or granules for oral suspension) and for parenteral administration (in the form of an injectable solution).
Morphine administered subcutaneously reaches the apex of the analgesic effect in a time ranging from thirty to sixty minutes; this effect lasts from four to six hours. The intravenous injection, on the other hand, allows a more rapid peak of action, which is more intense; the overall duration of the effects is similar.
The amount of morphine to be taken must be established by the doctor on an individual basis, depending on the intensity of the pain that afflicts each patient.
In elderly and debilitated patients it may be necessary to reduce the doses of morphine usually used in therapy.
Pregnancy and breastfeeding
Because of the damage it can cause to the newborn (respiratory depression and withdrawal syndrome in the case of chronic administration in the mother), the use of morphine by pregnant women is not recommended.
Furthermore, morphine is excreted in breast milk, therefore its use by breastfeeding mothers is also generally contraindicated.
In any case, pregnant women and breastfeeding mothers should always seek the advice of their doctor before taking any type of medicine.
Contraindications
The use of morphine is contraindicated in the following cases:
- In patients with known hypersensitivity to morphine and / or to derivatives of the same morphine (such as, for example, codeine);
- In patients with acute abdomen and paralytic ileus;
- In patients with severe hepatocellular insufficiency;
- In patients suffering from respiratory depression or chronic lung diseases;
- In patients with ongoing bronchial asthma attack;
- In patients with secondary heart failure;
- In patients with head trauma or suffering from intracranial hypertension;
- In patients who have undergone biliary tract surgeries;
- In patients with convulsive states or those with uncontrolled epilepsy;
- In patients with central nervous system depression, especially if induced by drugs such as sedative-hypnotics, anxiolytics, etc .;
- In patients taking - or who have recently taken - monoamine oxidase inhibitors;
- In patients already being treated with naltrexone;
- In patients with acute alcoholism or with delirium tremens;
- Pregnant;
- During breastfeeding.
Morphine and heroin
An important morphine derivative, obtained by acetylation at positions 3 and 6, is heroin. Although having less affinity for the opioid receptors that mediate their effects, heroin possesses about double the analgesic activity. This apparent contradiction is linked to its greater lipophilicity, which allows it to rapidly cross the blood-brain barrier and carry out its euphoric effects at the central level. For these reasons, drug addicts prefer it to morphine. Unlike the latter, heroin is not considered a drug.
