The cause of fibromyalgia is unknown; however, it is believed to involve a combination of genetic and environmental factors with half the risk attributed to each. The condition runs in families and many genes are believed to be involved.
Agonist: A substance that acts like another substance and therefore stimulates an action. Agonist is the opposite of antagonist. Antagonists and agonists are key players in the chemistry of the human body and in pharmacology.
Examples of opiate agonists include methadone and LAAM. These synthetic opiates help prevent cravings and withdrawal but do not produce a high or feelings of euphoria. An opiate antagonist is a drug that replaces opiate agonists at the receptor sites.ethadone is the most widely known and most common of opiate agonists used to treat opioid dependence. It decreases drug cravings and has helped many patients wean off opiates. It is dispensed in a licensed methadone maintenance clinic where patients must go to receive their dose.