Metformin is Not a Metal-Forming Drug
The question appears to contain a misunderstanding. Metformin is a biguanide antidiabetic medication, not a "metal-forming" class of drug. However, I can clarify what "metal-forming" drugs actually are and provide relevant information about metal chelation therapy, which may be what you're asking about.
Metal Chelation Drugs (Not "Metal-Forming")
Metal chelation drugs bind to and remove excess metals from the body, rather than forming metals. These are used in conditions of metal overload:
Copper Chelation Agents
For Wilson's disease (copper overload), D-penicillamine is the primary chelating agent with typical dosing of 250-500 mg/day initially, increased by 250 mg increments every 4-7 days to a maximum of 1000-1500 mg daily in 2-4 divided doses 1. Alternative agents include:
- Trientine: Used when penicillamine causes side effects 2, 3
- Tetrathiomolybdate: Successfully employed as an alternative chelator 4
- Zinc salts: Block copper absorption from the gut by inducing metallothionein synthesis; very effective for maintenance therapy with almost no side effects, though cannot be used as initial treatment 4
Iron Chelation Agents
For iron overload conditions (hemochromatosis, thalassemia), deferiprone is a key oral chelator 5, 6:
- Deferiprone dosing: 1,000 mg tablets three times daily or 500 mg tablets three times daily 7
- Deferoxamine (DFO): Parenteral iron chelator used effectively alone or in combination with deferiprone 5, 6
- Deferasirox (ICL670): Once-daily oral chelator, though generally ineffective in causing negative iron balance and may increase iron absorption and redistribution 5
Important Drug Interactions for Metal Chelators
Deferiprone should not be co-administered with drugs causing neutropenia/agranulocytosis 7. Additionally:
- Avoid UGT1A6 inhibitors (diclofenac, probenecid, silymarin) with deferiprone 7
- Allow at least 4-hour interval between deferiprone and medications containing polyvalent cations (iron, aluminum, zinc, antacids) 7