The Clinical Guide to Supportive and Palliative Care for HIV/AIDS

A Clinical Guide to Supportive and Palliative Care for HIV/AIDS • Chapter 4: PainPemoline is a unique alternative psychostimulant that is chemically unrelated to amphetamine butmay have similar usefulness as an antidepressant and adjuvant analgesic in AIDS patients. 76 Advantagesof pemoline as a psychostimulant in AIDS pain patients include the following:26 picas• Lack of abuse potential• Lack of federal regulation through special triplicate prescriptions• Mild sympathomimetic effects• The fact that it comes in a chewable tablet form that can be absorbed through the buccalmucosa and thus can be used by AIDS patients who have difficulty swallowing or who haveintestinal obstructionClinically, pemoline is as effective as methylphenidate or dextroamphetamine in the treatment ofdepressive symptoms and in countering the sedating effects of opioid analgesics. There are no studiesof pemoline’s capacity to potentiate the analgesic properties of opioids. Pemoline should be usedwith caution in patients with liver impairment, and liver function tests should be monitored periodicallywith longer-term treatment. The Food and Drug Administration (FDA) suggests that whenpemoline is prescribed, patients sign an informed consent document that outlines the potential livertoxicities of pemoline.Modafinil, a novel psychostimulant that has shown efficacy in treating excessive daytime sleepinessassociated with narcolepsy, has recently demonstrated potential for the treatment of depression andfatigue. 121 Although modafinil needs further study, it appears to be a promising alternative to otherpsychostimulants in patients who cannot tolerate or have contraindications to the use of otherstimulants. Modafinil has minimal cardiovascular effects, does not cause tolerance or dependence,has a low abuse potential, and does not require a special triplicate prescription.IVAnticonvulsant DrugsSelected anticonvulsant drugs appear to be analgesic for the lancinating dysesthesias that characterizediverse types of neuropathic pain. 111 Clinical experience also supports the use of these agentsin patients with paroxysmal neuropathic pains that may not be lancinating and, to a far lesser extent,in those with neuropathic pains characterized solely by continuous dysesthesias. Although mostpractitioners prefer to begin with carbamazepine because of the extraordinarily good response rateobserved in trigeminal neuralgia, this drug must be used cautiously in AIDS patients with thrombocytopenia,those at risk for marrow failure, and those whose blood counts must be monitored to determinedisease status. If carbamazepine is used, a complete blood count should be obtained prior to thestart of therapy, after two and four weeks, and then every three to four months thereafter. A leukocytecount below 4000 is usually considered to be a contraindication to treatment, and a decline to lessthan 3000 or an absolute neutrophil count of less than 1500 during therapy should prompt discontinuationof the drug. Other anticonvulsant drugs may be useful for managing neuropathic pain inAIDS patients, including phenytoin, clonazepam, valproate and gabapentin. 111Several newer anticonvulsants have been used in the treatment of neuropathic pain, particularlywith patients who have reflex sympathetic dystrophy. These drugs include gabapentin, lamotrigine,tiagabine, and felbamate. Of these newer anticonvulsants, experience has been most favorable withgabapentin, now being widely used by pain specialists to treat neuropathic pain of various types.Gabapentin has a relatively high degree of safety, with no known drug-drug interactions and a lackof hepatic metabolism. 111 Treatment with gabapentin is usually initiated at a dose of 300 mg/day andthen gradually increased to a dose range of 900-3200 mg/day in three divided doses.U.S. Department of Health and Human Services • Health Resources and Services Administration • HIV/AIDS Bureau 113