Medical Definition of metastatic. 1  1: of, relating to, or caused by metastasis cutaneous metastatic disease as the first sign of lung cancer metastatic carcinoma metastatic spread. 2  2: tending to metastasize metastatic cancer cells metastatic prostate cancer.
Acetylcholinesterase inhibitor (generally referred to as cholinesterase inhibitor): a chemical that binds to the enzyme, cholinesterase, and prevents it from breaking down the neurotransmitter, acetylcholine.
Since anticholinesterase medications do not target the immune problem in MG, they do not alter the course of the disease. Thus, they are not a treatment, but provide a short term boost to help patients function better. The most commonly prescribed medication of this type is pyridostigmine bromide (Mestinon).