This medication binds to opioid receptors and enhances their effect. Three types of opioid receptors exist, mu, kappa, and delta with mu being the primary target of morphine to reduce pain.
Morphine is specifically used in situations of chronic or severe pain such as with cancer, pancreatitis or traumatic injuries. With chronic pain this medication is often delivered in a patient controlled anesthesia (PCA) pump which allows for continuous dosing based on the patient’s perceived level of pain up to a maximum dose.
Morphine is also indicated during myocardial infarction for two reasons. It decreases the anxiety level and pain experienced by the patient, which decreases stress and sympathetic responses, but also has vasodilating effects all of which decrease the oxygen demand of the heart. Morphine may also be used in angina and pulmonary edema for similar reasons.
Often patients may experience nausea and vomiting as this medication may stimulate the chemoreceptor trigger zone (CTZ) in the brain. Slow administration of the medication decreases the side effect.
CNS depression, especially respiratory rate, is a side effect of major concern. Ensure the patient’s respiratory rate is adequate and frequently assess the patient’s level of consciousness. This medication also causes a euphoric state.
This medication may cause a spasm of the bile duct and subsequently serious abdominal pain, as bile is unable to leave the gall bladder into the duodenum.
A very common side effect of all opioid medications is constipation. The frequency of the side effect increases with long term use and high dosing. Some patients are often given stool softeners to prevent this common side effect. Urinary retention can also occur.
Caution should be exercised when giving this medication to patients with head injuries as it may cause an increase in intracranial pressure.
Opioid medications cause miosis or pupillary constriction. Proper assessment of the patient’s pupils could help in the identification of a medication that was taken.
Decrease in blood pressure is a common side effect of this medication due to its vasodilatory effects. Check the blood pressure of patients before administration.
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