Isotretinoin
Mechanism :
Isotretinoin is a retinoid which inhibits sebaceous gland function and keratinization. The exact mechanism of action of isotretinoin is unknown.
Indication :
- Severe Recalcitrant Nodular Acne
- Ichthyosis
Contraindications :
Contraindicated in patients who are hypersensitive to this medication or to any of its components. Should not be given to patients who are sensitive to parabens, which are used as preservatives in the gelatin capsule, in hepatic and renal impairment and hyperlipidemia. Pregnancy must be excluded before therapy and contraceptive measures taken in women of child-bearing potential.
Dosing :
Under 12 years:
Safety and efficacy not established.
Above 12 years:
0.5-1 mg/kg/day in two divided oral doses for 15-20 weeks.
Adverse Effect :
Vascular thrombotic disease, tachycardia, palpitation, stroke, allergic reactions, including edema, systemic hypersensitivity, vasculitis, lymphadenopathy, fatigue, weight loss, xerosis, hepatitis, inflammatory bowel disease, esophagitis/esophageal ulceration, bleeding and inflammation of the gums, pancreatitis, colitis, cheilitis, xerostomia, anemia, thrombocytopenia, neutropenia, allergic reactions, epistaxis, alterations in blood sugar levels, hypertriglyceridemia, calcification of tendons and ligaments, myalgia, premature epiphyseal closure, decreases in bone mineral density, skeletal hyperostosis, back pain, arthralgia, drowsiness, headache, pseudotumor cerebri, lethargy, dizziness, insomnia, malaise, stroke, paraesthesia, nervousness, seizures, syncope, weakness, suicidal ideation, psychosis, depression, aggression, violent behaviours, blepharoconjunctivitis.
Interaction :
Vitamin A: Patients should be advised against taking vitamin supplements containing vitamin A to avoid additive toxic effects.
Tetracyclines: Concomitant treatment with tetracyclines should be avoided because pseudotumor cerebri (benign intracranial hypertension) has been reported.
Micro-dosed Progesterone Preparations: Micro-dosed progesterone preparations ("minipills" that do not contain an estrogen) may be an inadequate method of contraception during isotretinoin therapy.
Systemic Corticosteroids: Systemic corticosteroids are known to cause osteoporosis, there may be an interactive effect on bone loss between systemic corticosteroids and isotretinoin.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
20-50 | Dose as in normal renal function |
10-20 | Dose as in normal renal function |
<10 | Initial dose 10 mg daily and slowly increase as tolerated up to 1 mg/kg daily. |
Dose in Patients undergoing Renal Replacement Therapies
CAPD | Not dialysed. Dose as in GFR<10 mL/min |
HD | Not dialysed. Dose as in GFR<10 mL/min |
HDF/High flux | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
CAV/VVHD | Not dialysed. Dose as in normal renal function |
Hepatic Dose :
No dose adjustments are recommended.