Indication

Dandruff, Seborrheic dermatitis of the scalp, Pityriasis versicolor

Administration

To use the Ketoconazole shampoo, follow these steps: Use a small amount of water to wet the area where Ketoconazole shampoo is to be applied. Apply the shampoo to the affected skin/scalp and a large area around it. Use fingers to rub the shampoo until it forms lather. Leave the shampoo on skin/scalp for 5 minutes. Rinse the shampoo off skin/scalp with water.

Adult Dose

Seborrheic Dermatitis Cream: Apply q12hr for 4 weeks or until clear Shampoo: Apply twice weekly for 4 weeks, with at least 3 days between each shampoo Tinea Versicolor Shampoo Wet hair, massage into scalp for 1 min, and rinse Repeat, leaving on scalp for 3 additional min Shampoo twice weekly for 4 weeks, allowing 3 days between each shampoo Tinea Corporis, Tinea Cruris, Tinea Pedis Cream: Apply qDay for 2 weeks (6 weeks for tinea pedis), covering affected area

Child Dose

Seborrheic Dermatitis <12 years: Safety and efficacy not established >12 years (shampoo): Apply twice weekly for 4 weeks, with at least 3 days between each shampoo >12 years (cream): Apply to affected area q12hr x4 weeks

Contraindication

Known hypersensitivity to ketoconazole or any of the excipients.

Mode of Action

Ketoconazole interferes w/ biosynthesis of triglycerides and phopholipids by blocking fungal CYP450, thus altering cell membrane permeability in susceptible fungi. It also inhibits other fungal enzymes resulting in the accumulation of toxic concentrations of hydrogen peroxide.

Precaution

In patients who have been on prolonged treatment with topical corticosteroids, it is recommended that the steroid therapy be gradually withdrawn over a period of 2 to 3 weeks, while using Ketoconazole 2% shampoo to prevent any potential rebound effect. Avoid contact with the eyes. If the shampoo enters the eyes, rinse immediately with plenty of water. Lactation: Not known if distributed into milk; use caution

Side Effect

1-10% Irritation, severe,Pruritus,Stinging Frequency Not Defined Shampoo Hair loss/alopecia,Irritation,Abnormal hair texture,Scalp pustules,Dry skin,Pruritus,Oiliness/dryness of hair and scalp

Interaction

Reduced absorption w/ antimuscarinics, antacids, H2-blockers, PPIs, sucralfate. Reduced plasma concentrations w/ rifampicin, isoniazid, efavirenz, nevirapine, phenytoin. May also reduce concentrations of isoniazid and rifampicin. May reduce efficacy of oral contraceptives. May increase serum levels of CYP3A4 substrates e.g. digoxin, oral anticoagulants, sildenafil, tacrolimus. Potentially Fatal: May potentiate and prolong sedative and hypnotic effects of midazolam and triazolam. Increased plasma levels and prolonged QT intervals of astemizole, cisapride, dofetilide, pimozide, quinidine and terfenadine which may lead to torsade de pointes. Increased risk of myopathy w/ HMG-CoA reductase inhibitors (e.g. lovastatin, simvastatin). Markedly increased plasma levels of nisoldipine. Increased risk of hyperkalaemia and hypotension w/ eplerenone. Increased risk of vasospasm potentially leading to cerebral ischaemia w/ ergot alkaloids (e.g. ergotamine, dihydroergotamine).