Methadone nervous system

The dramatic heightening of aggressive behavior in morphine-withdrawn animals may be due to dopamine receptor upregulation (Gianutsos et al. 1975 Lai et al. 1975). Morphine and methadone inhibit dopamine receptors in the central nervous system (CNS) suggesting possible disuse... 

Severe pain should be treated with an opioid such as morphine, hydromorphone, methadone, or fentanyl. Moderate pain can be treated effectively in most cases with a weak opioid such as codeine or hydrocodone, usually in combination with acetaminophen. Meperidine should be avoided owing to its relatively short analgesic effect and its toxic metabolite, normeperidine. Normeperidine may accumulate with repeated dosing and can lead to central nervous system side effects including seizures. 

Methadone and opiates were first used for pain relief, and are still chiefly used in that area of medicine. It is important to remember that methadone and other opiates do not exert their pain control by altering a person s sensitivity to pain. Rather, methadone and other opiates interfere with the transmission of pain impulses from the nervous system to the brain. They accomplish this by a variety of methods. First, they decrease the transmission of nerve signals that conduct pain messages from various parts of the body to the spine. Secondly, they prevent production of neurochemicals that transfer this pain information to the spine. Finally, they mimic the actions of endorphins, which are the body s own pain-controlling chemicals. While methadone and other opiates work quite well to control pain, they do not affect touch, vision, or hearing. 

Another important side effect of all opiates on the central nervous system is respiratory depression. This is caused by an inhibitory effect on the brain stem, which is the part of the brain that controls breathing and other involuntary bodily systems such as heart beat, etc. Like nausea and vomiting, people who take methadone and other opiates normally develop a tolerance to this side effect. However, even people who have taken methadone for a long period of time can develop major respiratory depression. 

Fentanyl and methadone are highly protein bound and not dialyzable Constipation nausea central nervous system depression seizures (in conditions with lower seizure threshold)... 

NERVOUS SYSTEM A small cohort (n = 36) study demonstrated measurable cognitive deficits with recently initiated methadone therapy compared to normal controls. Patients on long-term methadone therapy, however, had cognitive abilities similar to control subjects [49 ]. 

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