Morphine / Codeine

Morphine

is a highly potent opiate analgesic drug and is the principal active agent in opium. Like other opiates, e.g. heroin, morphine acts directly on the central nervous system to relieve pain. Studies done on the efficacy of various opioids have indicated that, in the management of severe pain, no other narcotic analgesic is more effective or superior to morphine. Morphine is highly addictive when compared to other substances, and tolerance, physical and psychological dependences develop very rapidly.

Morphine is used legally:

• as an analgesic in hospital settings to relieve
• in the relief of severe chronic pain
• as an adjunct to general anesthetic
• as an antitussive for severe cough
• as an antidiarrheal in chronic cases

Effects on the immune system

Morphine has long been known to act on receptors expressed on cells of the central nervous system resulting in pain relief and analgesia.

Most of the licit morphine produced is used to make codeine.

Addiction

Morphine is a highly addictive substance, both psychologically and physically, with an addiction potential comparable to heroin. In a study comparing the physiological and subjective effects of heroin and morphine administered intravenously in post-addicts, the post-addicts showed no preference for one or the other of these drugs when administered on a single injection basis.

Withdrawal syndrome

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 strong drug craving, watery eyes, insomnia, diarrhea, runny nose, yawning, dysphoria, and sweating. 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. The heart rate and blood pressure are elevated. Chills or cold flashes with goose bumps ("cold turkey") alternating with flushing (hot flashes), kicking movements of the legs ("kicking the habit") and excessive sweating are also characteristic symptoms. Severe pains in the bones and muscles of the back and extremities occur, as do muscle spasms.

Major withdrawal symptoms peak between 48 and 96 hours after the last dose and subside after about 8 to 12 days. Sudden withdrawal by heavily dependent users who are in poor health is occasionally fatal, although morphine withdrawal is considered less dangerous than alcohol or barbiturate withdrawal.

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. The psychological dependence on morphine can, and usually does, last a lifetime.

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 the highest relapse rates among all drug users, including abusers of other opiods, cocaine and methamphetamine.

Other complication that may arise from long term morphine abuse, that is not seen with other narcotic analgesics, is neurotoxicity and brain damage. It is not fully understood yet exactly how morphine may cause neurotoxicity, but a metabolite of morphine may be responsible.

In the UK, morphine is listed as a Class A drug under the Misuse of Drugs Act 1072.

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