Ananalgesic adjuvant is amedication that is typically used forindications other thanpain control but provides control of pain (analgesia) in some painfuldiseases. This is often part of multimodalanalgesia, where one of the intentions is to minimize the need for opioids.[1][2][3]
Multimodal analgesia refers to the use of multiple classes of medications in order to treat pain from differentmolecular mechanisms at once. Prolonged use of higher doses of opioids is associated with increased risk oftolerance andopioid use disorder, so there is a growing trend in the use of multimodal analgesia to treat pain.[4][5][6]
Anticonvulsants work through blockade of sodium and calcium ion channels to reduce glutamate (excitatory neurotransmitter) release.[7] Nociceptor hyper-excitability, due to damage to pain-transmitting neurons, results in chronicneuropathic pain. Common anticonvulsants used to treat neuropathy aregabapentinoids (calcium channel blockers) andcarbamazapine (sodium channel blocker).[8] There is some evidence that anticonvulsants may also help with inflammatory pain through reduction of nociceptor hyper-excitability originally due to damage to surrounding tissue.[9]
Over-excitation of skeletal muscle can result inspasticity (increased muscle tone) and/ormuscle spasms (involuntary muscle contractions) which may contribute to pain.[15] There are several different types ofmuscle relaxants used for pain with different mechanisms of action. Muscle relaxants often have sedating effect that contributes to analgesia and improved relaxation. Experts disagree over whether muscle relaxants are useful for acute musculoskeletal pain.[16]
Alpha-2 adrenergic agonists such asclonidine are traditionally used to treat hypertension via inhibition of norepinephrine release.[17] Central alpha-2 adrenergic activation in thelocus ceruleus and spinal cord induce sedation and pain modulation respectively.[17]Clonidine has been shown to have some efficacy when treating both acute and chronic pain.[18]
