Drug-induced pigmentation

Drug induced pigmentation may take on many different appearances, one of the most common being a change in the color, or pigmentation, of the skin.
Cause.
Drug-induced pigmentation of the skin may occur as a consequence of drug administration, and the mechanism may be postinflammatory hyperpigmentation in some cases, but frequently is related to actual deposition of the offending drug in the skin.The incidence of this change varies, and depends on the type of medication involved. Some of the most common drugs involved are NSAIDs, antimalarials, psychotropic drugs, Amiodarone, cytotoxic drugs, tetracyclines, and heavy metals such as silver and gold (which must be ingested, not just worn).
Pathophysiology.
There are 4 possible mechanisms to how this change may occur: