Drug Topics - October 22, 2007 - (Page 30)

30 DRUG TOPICS OCTOBER 22, 2007 www.drugtopics.com CONTINUING EDUCATION carbidopa/levodopa. Antacids may tacks can occur at any time—for Table 3 be recommended to help decrease example, during driving or perOrganizations for patients the amount of acid and improve forming any daily activity; consethe drug’s absorption. Patients takquently, they could have a proand their caregivers ing iron supplements should be American Parkinson’s Disease Association found impact on personal safety. counseled to space the supplements After an attack, patients often do Phone: 800-223-2732 two hours from the administration not recollect its onset. A review of Web site: www.apdaparkinson.com of their carbidopa/levodopa. a patient’s medication history National Parkinson’s Disease Foundation Most adverse reactions caused by should be performed to aid in Phone: 800-327-4545 levodopa can be managed by adidentifying other possible sedating Web site: www.parkinson.org justing the frequency of administraagents that would increase the Michael J. Fox Foundation for Parkinson’s tion, changing the dose or dosage chance of hypersomnolence. Research form, or adding other antiparkinBromocriptine. BromocripPhone: 800-708-7644 son's agent. It is important to retine is an ergot derivative that Web site: www.michaeljfox.org member to start at a low dose and stimulates D2 receptors, α and WE MOVE slowly titrate levodopa doses to alserotonin receptors, while mildly Phone: 800-437-6682 low for maximum effect while minblocking D1 receptors. ComWeb site: www.wemove.org imizing side effects. Should disconpared with other dopamine agotinuation be warranted, withdrawal should be done gradually to nists, bromocriptine tends to be less efficacious, especially as reduce the risk of confusion, rigidity, and/or fever. monotherapy. As an adjunct to levodopa, bromocriptine allows Dopamine agonists. Five dopamine agonists are currently an overall reduction in 20% of levodopa dosing. (See Table 4 available on the U.S. market: bromocriptine, pramipexole, ropini- for dosing parameters.) Bromocriptine is rapidly absorbed and role, apomorphine, and rotigotine. Until recently, pergolide was undergoes high first-pass metabolism, is highly protein-bound, available and commonly used. However, two studies confirm and has multiple metabolites. Erythromycin, clarithromycin, findings associating pergolide with increased chance of regurgita- and nefazadone inhibit bromocriptine’s metabolism, signifition of the mitral, tricuspid, and aortic valves of the heart. As a re- cantly increasing its plasma concentrations. Bromocriptine has sult, pergolide was voluntarily withdrawn as of March 2007. For rarely been associated with pleuropulmonary fibrosis, which those who cannot successfully use other available agents, both the warrants monitoring, including chest X-rays. Food & Drug Administration and manufacturers are working to Pramipexole. Pramipexole is a non-ergot derivative that stimmake pergolide available through an Investigational New Drug ulates D3 receptors, which may provide antidepressive effects. It Application. is approved for monotherapy and allows for a 25%-30% reducDopamine agonists directly stimulate dopamine receptors. tion in daily levodopa when used in combination. Pramipexole Of the available dopamine agonists, all are beneficial for is excreted renally; thus, the dose must be adjusted in patients tremors, rigidity, and bradykinesia but not postural instability. whose creatinine clearance is <60 mL/minute. Cimetidine, ranDopamine agonists have been typically used as adjuncts to lev- itidine, triamterene, diltiazem, verapamil, quinidine, and quiodopa therapy in patients with deterioration or fluctuation, or nine may increase levels of pramipexole. in those who have an inability to tolerate higher doses of lev- Ropinirole. Ropinirole is a non-ergot derivative with high affinodopa. When dopamine agonists are used as adjuncts, practi- ity for D2 and D3 receptors. Combined with levodopa, it allows tioners may be able to decrease the dose of levodopa, resulting for a 30% dose reduction in levodopa. No dose adjustment is in fewer reported side effects. needed in patients with renal insufficiency, since ropinirole is meDopamine agonists may also be used as early monotherapy. tabolized by CYP1A2. However, patients concomitantly taking If a patient does not benefit from or is intolerant of one agonist, potent inhibitors of 1A2, such as fluoroquinolones, will likely lead another dopamine agonist should be tried. To prevent neu- to increased plasma levels of ropinirole. roleptic malignant syndrome, abrupt discontinuation should be Apomorphine. Apomorphine stimulates both D1 and D2 reavoided. Converting from one agonist to another may be ac- ceptors. It is specifically indicated as adjunct/supplemental complished by using the appropriate dosing equivalency (i.e., therapy to standard levodopa therapy for the acute, intermitbromocriptine 10 mg = ropinirole 4 mg = rotigotine 4 mg = tent treatment of hypomobility (freezing episodes) seen in papramipexole 1 mg). tients with advanced Parkinson’s disease. It is the first treatAdverse reactions are similar among all the dopamine agonists ment approved for this indication in the United States. and are frequently dose-related. They occur commonly at the on- Apomorphine is administered subcutaneously through an inset of therapy and can be a limiting factor. Nausea is the most jector-pen device due to its poor bioavailability. It has been ascommon side effect, followed by sedation, light-headedness, and sociated with a very high incidence of nausea and/or vomitvivid dreams. Asymptomatic postural hypotension is common at ing, especially at initial treatment. Thus, an antiemetic first dose but does not always require dose adjustment. Edema regimen should be recommended. may also be noted in some patients taking a dopamine agonist. Rotigotine. Recently approved in May 2007, rotigotine is a nonSome psychiatric side effects include confusion, hallucinations, ergot derivative with specificity for D3, D2, and D1 receptors. hypersexual behavior, and daytime sedation. Unique to the other dopamine agonists, rotigotine is administered “Sleep attacks” is a term often used to describe the excessive daily through a silicone-based transdermal system. Therefore, padaytime sedation seen with dopamine agonist therapy. These at- tients with a silicone hypersensitivity should avoid this dopamine http://www.drugtopics.com http://www.apdaparkinson.com http://www.parkinson.org http://www.michaeljfox.org http://www.wemove.org

Table of Contents Feed for the Digital Edition of Drug Topics - October 22, 2007

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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