Morphine is a type of drug called an opioid. It works by activating opioid receptors that naturally exist in your body, which have a number of effects on your body. One of these is to provide analgesia and relieve pain, which is what the drug is used for.
Morphine is a relatively strong opioid and is usually used for moderate to severe pain. It can be taken for short-term acute pain, or on an ongoing basis for chronic pain.
Brand Names and Doses
Morphine is the generic name, or the name of the actual drug component inside the medication. There are many different brand names of morphine, depending on which company has manufactured the drug.
Brand names of morphine include:
- Sevredol tablets (10 mg or 20 mg doses)
- Anamorph tablets (30 mg dose)
- Momex tablets (10mg, 30mg, 60mg or 100mg doses)
- MS Contin tablets (5mg, 10mg, 15mg, 30mg, 60mg, 100mg or 200mg doses)
- Kapanol capsules (10mg, 20mg, 50mg or 100mg doses)
- Ordine liquid (1mg/mL, 2mg/mL, 5 mg/mL or 10 mg/mL doses)
- MS Contin Suspension oral liquid (20mg, 30mg, 60mg, 100mg or 200mg doses)
Momex, MS Contin, Kapanol and MS Mono are controlled release formulations. This means that they are produced in a special way so that the dose is slowly released from your stomach and into your bloodstream. As a result, you can take a dose less often because it lasts for a longer time.
It is important to swallow the controlled release tablets whole, as breaking or chewing them called interfere with the way they work.
What type of drug is it?
Morphine is a type of drug called an opioid. This is a drug class that helps us to group drugs that work in a similar way together. Other opioid medications include:
- Buprenorphine
- Codeine
- Dextropropoxyphene (Propoxyphene)
- Fentanyl
- Hydromorphone
- Methadone
- Oxycodone
- Pethidine
- Tramadol
What is Morphine used for?
Morphine is usually in the relief of moderate to severe pain because it is a relatively strong opioid. For milder pain, it is usually best to use a weaker opioid, such as codeine, because there is a lower risk of side effects.
Morphine may also occasionally be used relief of severe dyspnea or in combination with other medications for acute pulmonary oedema.
How does Morphine work?
Everyone naturally has endogenous opioids inside their body, which can bind to special receptors, called opioid receptors, to activate several effects in the body. When an endogenous opioid attaches to the right receptor, it can lead to several effects in the body including:
- Analgesia to relieve pain
- Slowing down of breathing
- Tiredness
- Difficulty defecating
Morphine manipulates this natural process by activating the same receptors that the endogenous opioids do. It mimics the effect of natural opioids in your body.
Morphine can also decrease the transmission of pain impulses in the body by interrupting the pain messages in the spinal cord and interfering with the messages coming from the brain in the central nervous system (CNS).
Side Effects
There are several general side effects of opioid medications such as morphine that can affect some people, such as drowsiness, dizziness, headache, dry mouth and urinating less often.
You can find out more information about some of the specific side effects by clicking on them below.
Nausea
Constipation
Respiratory Depression
Dependence
Cautions
When you take morphine, your body changes some of the drug into other substances in you liver, through a process called metabolism. Some of the metabolites of morphine (the substances that morphine can be converted into) can have effects on your body.
These metabolites need to be excreted in your urine but if you have poor renal or kidney function, they can accumulate and cause problems. Morphine is not usually recommended if you have renal impairment because there are alternative opioid drugs that can be used, such as fentanyl or oxycodone.
There are also some people who may need special attention if they take morphine due to other medications or health conditions they have. For example, if you have the following conditions often you may need a lower dose than usual:
- Slow heart rate
- Endocrine disease
- Hypothyroidism
- Adrenocortical insufficiency
- Myasthenia gravis
- Central nervos system (CNS) depression
- Frequent use of alcohol
Additionally, people with epilepsy are more likely to have a seizure while taking morphine, so this should be considered.
Special Cases
People who are elderly often require a lower dose of morphine than other adults. This is because their body takes longer to process the drug, so the concentration in the bloodstream builds up more quickly. As a result, elderly people are more likely to experience side effects, such as cognitive impairment, sedation and respiratory depression. They may also be at risk for having a fall.
Interactions
Taking morphine at the same time as another drug can sometimes change their effect on your body because of the way they interact.
If you take morphine at the same time as rifampicin, your body will metabolize morphine more quickly. This may decrease the pain relief and side effects, and the dose of morphine may need to be increased as a result.
Any medication that blocks the action of opioids, such as buprenorphine, naloxone or naltrexone, can decrease the action of morphine. These drugs are not usually used together.
All drugs that cause your breathing to slow down can increase the risk of a serious side effect of morphine: respiratory depression. Many drugs to lower blood pressure, such as beta blockers, can have this effect. This combination can be used, but it's important that your doctor knows that you are taking codeine and checks that the dose is right for your body.
Some drugs that are used in the treatment of depression called selective seretonin reuptake inhibitors (SSRIs) can cause a condition called seretonin toxicity. The risk of this is higher if morpine is taken at the same time, so you need to be on the lookout for early signs.
Pregnancy and Breastfeeding
Morphine is not usually recommended for women who are pregnant for two main reasons. Firstly, there is an increased risk of respiratory depression in the baby, which can be fatal. Secondly, the baby may experience withdrawal symptoms after birth due to the sudden decrease in dose of morphine when they are no longer connected to the mother's bloodstream.
Instead, it is best for pregnant women to take other medications ato relieve pain while they are pregnant, such as paracetamol. For more severe pain, a weaker opioid drug such as codeine is sometimes used.
For women who are breastfeeding, occasional doses of morphine may be used. There may still be some risk to your baby if they are used every day for an extended period of time, so it is best to keep the treatment time short, if possible.
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