A 17 year old girl with acne has been taking a drug for the last two years.She now presents with blue black pigmentation of nails.The likely medication causing above pigmentation is-
Mincycline induced pigmentation in acne- due to accumulation of iron in dermal macrophages occur with prolonged therapy 1-3 years high dose 200-300mg/day three different patterns - Localised at sites of previous inflammation -acne scars pretibial area generalised over the sun exposed sites and nails Ref Harrison 20th edition pg 1213
Tetracycline
Minocyclin
Doxycycline
Azithromycin
Skin lesions and disorders of pigmentation