Morphine is a potent narcotic pain reliever. This medication acts within the brain to alter the pain perception and response. Morphine also has other effects on the brain and body. It can be administered in a variety of ways, including intramuscular or intravenous injection, oral pills, lozenges and liquids. The liquid form of morphine is absorbed from the stomach and provides maximum pain relief approximately one hour after ingestion.
Pain Relief
In the 2008 article, "Opioids in the Management of Chronic Non-Cancer Pain: An Update of American Society of the Interventional Pain Physicians' (ASIPP) Guidelines" published in Pain Physician, Dr. A. Trescot and colleagues note that morphine mimics the actions of naturally occurring pain-blocking chemicals in the brain, including enkephalins, endorphins and dynorphins. By mimicking the actions of these substances, morphine provides pain relief. Morphine is one of the most potent pain relievers known. Increasing doses provide increasing levels of pain relief.
Altered Mood
Morphine acts at a particular site on brain cells called the mu receptor. Stimulating the mu receptor not only provides pain relief but also commonly leads to euphoria. Euphoria is a psychological state of happiness and well-being that is both calming and pleasant. People under the influence of morphine are typically unconcerned with everyday worries. The euphoric effects of morphine may be a contributing factor to abuse of this medication, according to the National Institute on Drug Abuse.
Drowsiness and Sedation
Morphine is a brain-activity depressant, which means it typically causes drowsiness and sedation. Increasing levels of drowsiness occur as the morphine dose increases. In an interview with the National Pain Foundation, pain specialist Dr. Jennifer Schneider pointed out that people taking morphine long term usually become tolerant to the sedative effects of the drug. This means morphine causes less drowsiness over time when taken long term.
Slow Digestion and Constipation
All forms of morphine cause decreased secretion of stomach acid and reduced muscular activity of the stomach and small intestine. These effects result in a slowed rate of food digestion. People on morphine for long durations may notice that their stomachs feel full for a longer period than normal after eating. "The Merck Manual for Healthcare Professionals" advises that decreased muscular activity of the large intestine frequently causes constipation in people taking morphine for more than a few days. Laxatives and increased fiber in the diet are often needed to relieve morphine-related constipation.
Altered Breathing Rate
Morphine affects the breathing regulation center in the brain stem, causing depression in the rate of breathing. "The Merck Manual for Healthcare Professionals" notes that significant decreases in breathing rate are uncommon with typical doses of morphine. However, morphine overdose may cause respiratory arrest.
References
- Drugs.com: Morphine Oral Solution, FDA Monograph
- Pain Physician: Opioids in the Management of Chronic Non-Cancer Pain: An Update of American Society of the Interventional Pain Physicians' (ASIPP) Guidelines
- Merck Manual: Pain, Opioid Analgesics
- American Cancer Society: Morphine
- National Institute on Drug Abuse: NIDA InfoFacts, Prescription and Over-the-Counter Medications
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