| myalgia is a chronic disorder characterized by chronic, | | | | altered GABA function. The excitatory/inhibitory |
| widespread muscle pain and tenderness, and is | | | | neurotransmitter balance acts as a master regulator |
| frequently accompanied by fatigue, insomnia, | | | | of the sensitivity of the nervous system. |
| depression, and anxiety. It affects three million to six | | | | Many anticonvulsant drugs-drugs used to treat |
| million Americans, mostly women, and can be | | | | epilepsy- lead to an increase in GABA signaling by |
| disabling. | | | | inhibiting firing. Derivatives of the common |
| The precise cause of fibromyalgia in not known, but | | | | anticonvulsant valproic acid (Depakote) alter levels of |
| research suggests it is related to a problem with the | | | | GABA in the brain. Tiagabine (Gabitril) and progabide |
| central nervous system’s processing of pain. | | | | (Gabrene) are also agonists of GABA receptors, |
| As with some other chronic pain conditions, people | | | | meaning they bind to and activate these receptors |
| with fibromyalgia often develop a heightened | | | | which are located on neurons (nerve cells). This is |
| response to stimuli, experiencing pain that would not | | | | also the mechanism of action for benzodiazepines, |
| cause problems in other people. Yet, unlike many | | | | such as clonazepam (Klonapin). |
| other pain syndromes, there is no physical evidence | | | | Lyrica and Neurontin, are GABA analogs, meaning |
| of inflammation or central nervous system damage. | | | | they resemble GABA enough to function the same |
| As mentioned above, the current theory regarding | | | | way in the nervous system. |
| the reason fibromyalgia causes its symptoms is that | | | | In a recent double-blind study sponsored by the |
| there is hypersensitization of the central nervous | | | | National Institute of Arthritis Musculoskeletal and Skin |
| system. Pain signals are transmitted more frequently | | | | Diseases, researchers found that those taking |
| than they should be. | | | | gabapentin at dosages of 1,200 to 2,400 mg daily for |
| Recently, anticonvulsant drugs such as gabapentin | | | | 12 weeks displayed significantly less pain than those |
| (Neurontin) and pregabalin (Lyrica) have been used to | | | | taking placebo. Patients taking gabapentin also |
| reduce the level of this excess firing. | | | | reported significantly better sleep and less fatigue. |
| Neuronal activity in the brain can be modified by the | | | | For the majority of participants, the drug was well |
| presence of excitatory or inhibitory | | | | tolerated. The most common side effects included |
| neurotransmitters, which exist in balance in the | | | | dizziness and sedation, which were mild to moderate |
| nervous system. The ratio of these chemicals | | | | in severity in most cases. |
| determines how likely it is that a neuron will fire. Two | | | | Although gabapentin has little, if any, effect on acute |
| major excitatory neurotransmitters are amino acids: | | | | pain, it has shown a robust effect on pain caused by |
| glutamate and aspartate. Two main inhibitory | | | | a heightened response to stimuli related to |
| neurotransmitters are glycine, another amino acid, and | | | | inflammation or nerve injury in animal models of |
| GABA (gamma aminobutyric acid), a derivative of | | | | chronic pain syndromes. |
| glutamate. The excitatory chemicals increase the | | | | Recent evidence also points toward a beneficial |
| charge of neurons, while inhibitory ones make the | | | | effect also occurring from the use of Lyrica in FM. |
| neurons more negatively charged (less likely to fire). | | | | The dose required for effectiveness in fibromyalgia |
| When neurons fire, they release other | | | | for both gabapentin (Neurontin) as well as pregabalin |
| neurotransmitters like serotonin and dopamine. This | | | | (Lyrica)is generally much higher than the dose |
| means that the decrease in serotonin levels often | | | | required for anti-seizure activity. This is particularly |
| seen in FM patients could possibly be a result of | | | | true for Lyrica. |