Drug Topics - October 22, 2007 - (Page 32)

32 DRUG TOPICS OCTOBER 22, 2007 www.drugtopics.com CONTINUING EDUCATION methamphetamine and amphetamine, which can cause insomnia and restlessness. Counseling to take this medication in the morning may help the patient avoid these side effects. Unlike selegiline, rasagiline does not metabolize into methamphetamine or amphetamine. Rasagiline also may cause less confusion and therefore may be better tolerated in older PD patients, compared with selegiline. Since both drugs at regular doses do not inhibit MAO-A, the possibilities of tyramine food interactions are unlikely. Thus, diet restrictions are not necessary. Serotonin syndrome, characterized by hypertension, diaphoresis, and chills, is also rare when patients are on both an SSRI and an MAO-B inhibitor, but caution should still be exercised. Regardless of the dose, concomitant use of both selegiline and meperidine is contraindicated due to an increased risk of serotonin syndrome. patient-specific regimens should be individualized. The AAN updated the evidence-based guidelines in 2006 for the medical treatment of Parkinson’s disease, and it continues to use the 2002 evidence-based guidelines for the initiation of treatment for a PD patient. When approaching therapy in a PD patient, the AAN recommends the following: •Initial symptomatic treatment of a PD patient in order to confer a mild, symptomatic benefit; prior to the institution of any dopaminergic therapy, selegiline should be considered. •In patients who have motor fluctuations, amantadine may be considered in reducing dyskinesia. •In patients who require initiation of a dopaminergic agent, levodopa or a dopamine agonist should be used. Levodopa should be chosen if the purpose is to improve motor disability, while a dopamine agonist should be selected if the purpose is to lessen motor complications. •Entacapone or rasagiline should be offered first to reduce “off time” in PD patients with motor fluctuations. If unsuccessful, another dopamine agonist should be attempted. While initial treatment of a PD patient may be not complicated, patients begin to experience severe motor fluctuations and cognitive decline as the disease advances. Inevitably therapeutic management becomes challenging and requires a careful balance between the benefit in reduction of symptoms and the risk of long-term side effects. Catechol-O-methyltransferase inhibitors Entacapone and tolcapone are both reversible selective inhibitors of the enzyme catechol-O-methyltransferase (COMT). COMT is the main enzyme that metabolizes levodopa, resulting in the metabolite 3-O-methyldopa (3OMD). 3OMD interferes with the transport of levodopa into the central nervous system. By inhibiting COMT, levodopa concentrations are more sustained, providing more levodopa to the central nervous system for conversion to dopamine. Addition of the COMT inhibitors to levodopa therapy prolongs the effects of levodopa therapy, enabling a dose reduction. Since MAO and COMT are the two major enzymes involved in catecholamine metabolism, both entacapone and tolcapone are contraindicated with any other nonselective MAO inhibitors. Tolcapone has a black box warning of the risk of fulminate hepatic failure. Patients on tolcapone should have their LFTs monitored every two weeks. Treatment should be discontinued if LFTs rise above the upper limit of normal or any symptoms of hepatic failure become apparent. Hepatotoxicity has limited the clinical use of tolcapone. While there have been no reports of hepatotoxicity with entacapone, patients have reported a brownish-orange discoloration of their urine and therefore patient counseling is necessary. Delayed-onset diarrhea may be significant enough in some patients to necessitate COMT inhibitor discontinuation. Alternative treatments Many people use alternative therapies such as herbals, vitamins, and acupuncture for treatment of various conditions. Coenzyme Q10, folic acid, vitamin E, and vitamin C all have been studied as potential neuroprotective agents for PD. However, results from several of the trials are not in support of these agents. Conversely, since there is low potential of harm and minimal, if any, benefit, many practitioners recommend them to their patients for their antioxidant benefits. Acupuncture has also been investigated, as it is thought to promote blood circulation and energy. It may be beneficial in patients with both vascular dementia and PD. Guideline approach to therapy Prior to initial treatment, a complete history and physical exam should be performed, with careful attention to the patient’s functional and cognitive impairments. While guidelines have been provided by the American Academy of Neurology (AAN), The pharmacist’s role Pharmacists are in a position to play a key role in PD care. One major concern with all pharmacologic therapies is compliance—crucial in PD patients. This can be improved through pharmacist-mediated medication assessment and consultation. Many patients abruptly stop their medications if they perceive they are not receiving any benefit. Therefore, it is important to inform both patients and their caregivers about the length of time it may take to begin to observe results from their medication. Besides telling patients about expected efficacy, it is important to discuss possible side effects they may experience. Some of the side effects are related to the timing of administration. Thus, pharmacists can instruct patients about when to appropriately take medications to possibly avoid side effects. The complexity of some PD regimens is another barrier to compliance. Pharmacists can work with patients, caregivers, and physicians to recommend ideas on reducing the complexity of the dosing regimen. One example may be to recommend switching to a controlled-release carbidopa/levodopa from an immediate-release formulation or suggest optimal dosing to avoid the “off” phenomenon. PD patients may also present to the pharmacy inquiring about OTC medications for other symptoms. One frequent complaint of these patients is constipation. This can often be alleviated by changes in dietary fiber or supplementation and stool softeners. Some cases may warrant referral to a physician. Another complaint may be insomnia. It is important to remember that most OTC sleep aids may have anticholinergic side effects, which can be problematic. Finally, pharmacists can assist patients and caregivers in locating either local or national Parkinson’s disease organizations that can provide resources and education. (See Table 3.) References are available upon request. http://www.drugtopics.com

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Drug Topics - October 22, 2007 Contents Latebreakers Legislative Victory Builds Momentum for Pharmacy Month Letters Health-System Edition R.Ph.s Brace for Payment Denial for Hospital-Acquired Conditions Topical Human Thrombin Helps Arrest Bleeding FDA Panels Fail to Set Target Levels for Renal Patients’ Hemoglobin Warning Letters Raise Patient Safety Concerns for Fentora Ending/Reversing Weight Gain Man Given Fatal Drug Overdose at Staten Island Hospital Pharmacists Playing More Important Role in Dialysis Treatment AHA President R.Ph.'s Here's How You Can Increase Your Value Premier Launches Comprehensive Quality Improvement Project FDA Approves Dexrazoxane for Treatment of Extravasation New Federal, State Reforms to Ease Disaster Relief Kinks 150 Years of American Pharmacy Ten Tips for MTM Success Independent Superstars: The Ones to Watch The New Dynamic Duo A Parkinson's Disease Primer Classified New Products Advertisers Index Viewpoint

Drug Topics - October 22, 2007

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