May 28, 2017
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(metyrosine) Capsules


DEMSER* (Metyrosine) is (–)-α-methyl-L-tyrosine or (α-MPT). It has the following structural formula:

  (METYROSINE) Structural Formula Illustration

Metyrosine is a white, crystalline compound of molecular weight 195. It is very slightly soluble in water, acetone, and methanol, and insoluble in chloroform and benzene. It is soluble in acidic aqueous solutions. It is also soluble in alkaline aqueous solutions, but is subject to oxidative degradation under these conditions.

DEMSER (metyrosine) is supplied as capsules, for oral administration. Each capsule contains 250 mg metyrosine. Inactive ingredients are colloidal silicon dioxide, gelatin, hydroxypropyl cellulose, magnesium stearate, titanium dioxide, and FD&C Blue 2.

What are the possible side effects of metyrosine (Demser)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • drooling;
  • difficulty speaking;
  • tremors;
  • muscle spasms;
  • disorientation;
  • diarrhea; or
  • painful urination.

Less serious side effects may include:

  • headache;
  • drowsiness;
  • depression, hallucinations, disorientation, and confusion;
  • stomach upset, vomiting,...

Read All Potential Side Effects and See Pictures of Demser »

What are the precautions when taking metyrosine (Demser)?

Before taking metyrosine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, severe loss of body water (dehydration), small amount of urine.

Before having surgery, tell your doctor or dentist that you are taking this medication.

This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Avoid alcoholic beverages because alcohol may increase...

Read All Potential Precautions of Demser »

Last reviewed on RxList: 12/8/2016
This monograph has been modified to include the generic and brand name in many instances.

Demser - User Reviews

Demser User Reviews

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Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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