Ketoconazole 2% shampoo

Indications

Ketoconazole 2% shampoo is used for: Dandruff, Seborrheic dermatitis of the scalp, Pityriasis versicolor

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

Renal Dose

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.

Contra Indications

Known hypersensitivity to ketoconazole or any of the excipients.

Precautions

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have been on prolonged treatment with topical corticosteroids, it is recommended that the steroid therapy be gradually withdrawn over a period of 2 to 3 weeks, while using Ketoconazole 2% shampoo to prevent any potential rebound effect.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

Pregnancy-Lactation

Pregnancy There are no available data on use in pregnant women to identify a drug-associated risk of birth defects, miscarriage or adverse maternal or fetal outcomes; no reproductive studies in animals have been performed; in animal reproduction studies with pregnant mice, rats and rabbits both embryotoxic and developmental effects (structural abnormalities) were observed following oral dosing of ketoconazole during organogenesis; assuming equivalent systemic absorption of topical and oral ketoconazole doses and a maximum recommended human dose (MRHD) of 8 grams (equivalent to 160 mg ketoconazole), embryotoxic effects were observed at 0.8 to 2.4 times the MRHD and developmental effects were observed at 4.8 times the MRHD Infertility In animal fertility studies in rats and dogs, administration of oral doses of ketoconazole between 3-day and 3-month periods resulted in infertility that was reversible Lactation There is no information available on presence of ketoconazole in human milk, or effects on breastfed child, or effects on milk production after topical application to women who are breastfeeding; in animal studies ketoconazole was found in milk following oral administration; the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for therapy and any potential adverse effects on breastfed infant from treatment or from underlying maternal condition

Interactions

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).

Side Effects

Side effects of Ketoconazole 2% shampoo : 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

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.