Medication Summary
The goals of pharmacotherapy are to reduce morbidity and prevent complications.
Local Anesthetics
Class Summary
Treatment of iliohypogastric or ilioinguinal nerve entrapment may include local injection of an anesthetic.
Lidocaine (Xylocaine)
Lidocaine is an amide local anesthetic used in a 0.5-1% concentration in combination with bupivacaine (50:50 mixture). This agent inhibits depolarization of type C sensory neurons by blocking sodium channels.
Bupivacaine (Marcaine, Sensorcaine)
Bupivacaine 0.25% may be used in combination with lidocaine plus epinephrine (50:50 mixture). It decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses.
Anticonvulsants, Other
Class Summary
Some agents in this category have shown benefit in the treatment of neuropathic pain.
Pregabalin (Lyrica)
Pregabalin is a structural derivative of gamma-aminobutyric acid (GABA). Its mechanism of action is unknown. The drug binds with high affinity to the alpha2-delta site (a calcium channel subunit). In vitro, it reduces the calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function.
Gabapentin (Neurontin)
Gabapentin, a membrane stabilizer, is a structural analogue of the inhibitory neurotransmitter GABA, although, paradoxically, it is thought not to exert an effect on GABA receptors. It appears to exert its action via the alpha2delta1 and alpha2delta2 auxiliary subunits of voltage-gaited calcium channels.
Carbamazepine (Tegretol, Carbatrol, Epitol)
Carbamazepine has antineuralgic effects. It may depress the activity of the nucleus ventralis of the thalamus or may decrease synaptic transmission or summation of temporal stimulation, thus leading to neural discharge by limiting the influx of sodium ions across the cell membrane or through other unknown mechanisms. The target blood serum concentration range is 4-12 mg/L.
Antidepressants, TCAs
Class Summary
The analgesic properties of certain agents in this class may improve symptoms associated with neuropathic pain.
Amitriptyline
Amitriptyline is an analgesic for certain chronic and neuropathic pain. It blocks the reuptake of norepinephrine and serotonin, which increases their concentration in the central nervous system (CNS). Amitriptyline decreases pain by inhibiting spinal neurons involved in pain perception. This agent is highly anticholinergic. It is often discontinued because of somnolence and dry mouth. Cardiac arrhythmia, especially in overdose, has been described; monitoring the QTc interval after reaching the target level is advised. Up to 1 month may be needed to obtain clinical effects.
Clomipramine (Anafranil)
Clomipramine is a dibenzazepine compound belonging to the family of tricyclic antidepressants. The drug inhibits the membrane pump mechanism responsible for the uptake of norepinephrine and serotonin in adrenergic and serotonergic neurons.
Clomipramine affects serotonin uptake while it affects norepinephrine uptake when converted into its metabolite desmethylclomipramine. It is believed that these actions are responsible for its antidepressant activity.
Doxepin (Silenor)
Doxepin increases the concentration of serotonin and norepinephrine in the CNS by inhibiting their reuptake by the presynaptic neuronal membrane. It inhibits histamine and acetylcholine activity and has proven useful in the treatment of various forms of depression associated with chronic pain.
Nortriptyline (Pamelor)
Nortriptyline has demonstrated effectiveness in the treatment of chronic pain.
Desipramine (Norpramin)
This is the original TCA used for depression. These agents have been suggested to act by inhibiting reuptake of noradrenaline at synapses in central descending pain modulating pathways located in the brainstem and spinal cord.
Nonsteroidal Anti-Inflammatory Drugs
Class Summary
NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclo-oxygenase (COX) activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.
Ibuprofen (Motrin, Advil, Addaprin, Caldolor)
Ibuprofen is the drug of choice for patients with mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.
Naproxen sodium (Anaprox, Naprelan, Naprosyn, Anaprox)
This agent is used for the relief of mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing the activity of COX, which results in a decrease in prostaglandin synthesis.
Diclofenac (Voltaren, Cataflam XR, Zipsor, Cambia)
Diclofenac inhibits prostaglandin synthesis by decreasing COX activity, which, in turn, decreases formation of prostaglandin precursors.
Indomethacin (Indocin)
Indomethacin is used for relief of mild to moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of COX, which results in a decrease of prostaglandin synthesis.
Ketoprofen
Ketoprofen is used for relief of mild to moderate pain and inflammation. Small dosages are indicated initially in small patients, elderly patients, and patients with renal or liver disease. Doses higher than 75 mg do not increase the therapeutic effects. Administer high doses with caution, and closely observe the patient's response.
Opioid Analgesics
Class Summary
Tramadol is a weak opioid and an inhibitor of serotonin and norepinephrine reuptake in the dorsal horn.
Tramadol (Ultram, Conzip)
Tramadol is an analgesic that probably acts over monoaminergic and opioid mechanisms. Its monoaminergic effect is shared with tricyclic antidepressants. Tolerance and dependence appear to be uncommon.
Analgesics, Topical
Class Summary
Analgesics may aid in decreasing the severity of pain.
Lidocaine anesthetic (Topicaine, Lido Patch, Lidoderm 5% patch)
Several studies support topical administration of lidocaine as treatment of postherpetic neuralgia. In a placebo-controlled study, lidocaine gel (5%) yielded significant relief in 23 patients studied. Lidocaine tape also decreases the severity of pain.
Capsaicin topical (Capzasin-P, Trixaicin, Zostrix)
Capsaicin is a natural chemical derived from plants of the Solanaceae family. By depleting and preventing reaccumulation of substance P in peripheral sensory neurons, capsaicin may render treated areas insensitive to pain. Substance P is thought to be a chemomediator of pain transmission from the periphery to the CNS.
