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Pharmacological
Approaches to
Neuropathic Pain
Differential Diagnosis
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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
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
From: Bonica, “The Management of Pain”, 1990.
Neuropathic Pain
• Pain in absence or in addition
to nociceptive component
• Example – trigeminal
neuralgia
• Characteristics of pain
From: Bonica, “The Management of Pain”, 1990.
Treatment of Neuropathic Pain
• Surgical
• Drug therapy
From: Bonica, “The Management of Pain”, 1990.
Drug Therapy (Neuropathic
Pain)
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Carbamazepine
Phenytoin
Baclofen
Gabapentin
• Tricylic
antidepressants
• Local anesthetics
• Ketamine
• Clonazepam
Experimental Drug Therapy for
Neuropathic Pain
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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