Sunday, February, 12, 2012

Parkinson's Disease - Surgery

Table of Contents

Catechol-O-Methyl Transferase (COMT) Inhibitors

Catechol-O-methyl transferase (COMT) inhibitors increase concentrations of existing dopamine in the brain. Entacapone (Comtan, Stalevo) is the current standard COMT inhibitor. (Stalevo combines entacapone and levodopa into a single pill.) It improves motor fluctuations related to the wearing-off effect and has shown good results in improving on time and reducing the requirements for L-dopa. If the patient does not respond to the drug within 3 weeks, it should be withdrawn. No one should withdraw abruptly from these drugs.

Side Effects. Side effects may include:

  • Involuntary muscle movements
  • Mental confusion and hallucinations
  • Cramps, nausea, and vomiting
  • Insomnia
  • Headache
  • Urine discoloration (a harmless side effect but should be reported to the doctor)
  • Diarrhea
  • Less commonly, constipation, susceptibility to respiratory infection, sweating, dry mouth

Of major concern are reports of a few deaths from liver damage in patients taking the COMT inhibitor tolcapone (Tasmar). The drug has been taken off the market in many countries and is recommended in the U.S. only for patients who cannot tolerate other drugs. Entacapone does not appear to have the same effects on the liver and does not require monitoring. Still, patients should watch out for symptoms of liver damage, including jaundice (yellowish skin), fatigue, and loss of appetite. The FDA is currently investigating whether Stavelo increases the risk of prostate cancer.

Jaundice
Jaundice is a condition produced when excess amounts of bilirubin circulating in the bloodstream dissolve in the subcutaneous fat (the layer of fat just beneath the skin), causing a yellowish appearance of the skin and the whites of the eyes. With the exception of normal newborn jaundice in the first week of life, all other jaundice indicate pigment overload (from excessive breakdown of red blood cells), damage to the liver, or inability to move bilirubin from the liver through the biliary tract to the gut.

Anticholinergic Drugs

Review Date: 06/18/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)