penicillamine
Meaning of penicillamine: A molecule that grips copper and other metals tightly enough to drag them out of the body in urine.
Definition of penicillamine
Penicillamine is a chelating drug that binds metals in the body and carries them out in the urine. Its main use is Wilson disease, an inherited disorder in which copper builds up in the liver and brain. It is also used for cystinuria, a kidney stone disorder, and was once used for rheumatoid arthritis. It derives from penicillin but has no antibiotic action.
How does chelation work?
A chelating agent wraps around a metal ion and grips it at several points at once, the way a claw closes on an object. The package that results is stable, dissolves in water and is filtered out by the kidneys. Penicillamine grips copper particularly well and also binds lead, mercury and zinc. It is a sulfur containing molecule related to the amino acid cysteine, and that sulfur atom does much of the gripping. Because the metal is escorted out rather than neutralized where it lies, the drug lowers the total amount in the body gradually rather than at once.
What is it used for?
| Condition | What penicillamine does |
|---|---|
| Wilson disease | Removes copper that has accumulated in liver, brain and eye |
| Cystinuria | Joins with cystine to form a more soluble compound, so stones form less readily |
| Heavy metal poisoning | Binds lead or mercury for removal in urine |
| Rheumatoid arthritis | Was used before better options existed, and is now rare |
In Wilson disease the treatment is lifelong, since the underlying fault in copper handling is inherited and does not resolve.
What is its relationship to penicillin?
Penicillamine is a breakdown product of penicillin and shares part of its structure, which is where the name comes from. It has no antibacterial activity at all, and it is not a cancer treatment despite appearing in older research literature on tumor blood vessels. The shared origin does raise one practical point, since a person with a severe penicillin allergy may react to it, although the two are different molecules and cross reaction is uncommon.
Why does it need close monitoring?
The drug is demanding to use. It can suppress the bone marrow, injure the kidneys and provoke autoimmune reactions affecting skin, muscle or the junction between nerve and muscle, so blood counts and urine are checked regularly throughout treatment. It also binds vitamin B6, which is given alongside for that reason. In Wilson disease, starting treatment can temporarily worsen neurological symptoms as stored copper is mobilized. Food and iron both reduce how much is absorbed. Newer chelators, and zinc, which blocks copper absorption instead of removing it, have taken over part of its former role.
Also known as
Used in a sentence
Penicillamine was started for Wilson disease, with blood counts and urine protein checked at regular intervals.
Good to know
Penicillamine is a metal chelator rather than an antibiotic or a cancer drug, despite deriving from penicillin, and its use calls for regular blood and urine monitoring because it can suppress the marrow and injure the kidneys.