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Pharmacological Approaches to Neuropathic Pain. Differential Diagnosis. Pain of dental origin Oral soft tissue pain Temporomandibular joint pain Myofascial pain dysfunction Neuropathic pain. From: Bonica, “The Management of Pain”, 1990. Pain Fibers. C A Changes in A.
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Differential Diagnosis • Pain of dental origin • Oral soft tissue pain • Temporomandibular joint pain • Myofascial pain dysfunction • Neuropathic pain
Pain Fibers • C • A • Changes in A
From: Dickinson & Fleetwood-Walker, Trends in Pharm. Sci. 20: 324, 1999.
Pain of Dental Origin • Physical findings • Pulpal and periodontal pain • Mucosal and other soft tissue pain • Radiographic findings • Nature and excitatory causes of pain
Treatment of Dental Pain • Operative or surgical intervention • Drug treatment • Anesthetics • NSAIDS • Opioids
Temporomandibular Joint dysfunctions • Disorders of muscles of mastication(myofascial pain dysfunction) • Internal joint derangement • Degenerative joint disease • Fractures, infections, tumors
Treatment of Myofascial Pain Dysfunction • Non-drug treatment • Drug treatment • NSAIDS, Opioids • Tricyclic antidepressants (amitriptyline) • Centrally-acting muscle relaxants • Glucocorticosteroids
Neuropathic Pain • Pain in absence or in addition to nociceptive component • Example – trigeminal neuralgia • Characteristics of pain
Treatment of Neuropathic Pain • Surgical • Drug therapy
Carbamazepine Phenytoin Baclofen Gabapentin Tricylic antidepressants Local anesthetics Ketamine Clonazepam Drug Therapy (Neuropathic Pain)
Experimental Drug Therapy for Neuropathic Pain • N-type calcium channel blockers • 2-adrenoceptor agonists (clonidine) • NMDA receptor antagonists • Selective serotonin reutake inhibitors • Adenosine receptor agonists • Valproic acid
Tricyclic Antidepressants • Inhibit reuptake of catecholamines and serotonin • Block NMDA receptors • Release endogenous opioids • Peripheral action
Carbamazepine (Tegretol) • Blocks sodium channels • Increases the release of catecholamines, thus indirectly stimulating 2-adrenoceptors
Baclofen (p-Chlorophenyl GABA) (Lioresal) • Inhibits the release of excitatory neurotransmitters • A GABAB receptor agonist
Valproic Acid (Depakene) • Increases GABA synthesis • Blocks sodium channels • Inhibits T (low threshold) calcium channels
Gabapentin (Neurontin) • Binds to Gabapentin-binding protein • Blocks calcium channels • Increases GABA synthesis • Reduces glutamate
Ketamine (Ketalar) • An NMDA receptor antagonist