Isotretinoin by the brand name Tretizen is a perfect drug for acne treatment which slows down the proliferation of epithelial cells of the ducts of the sebaceous glands, the formation of detritus, facilitates the evacuation of detritus, and normalizes terminal cell differentiation. Isotretinoin facilitates secretion and reduces sebum production. After oral administration, absorption of isotretinoin is variable, bioavailability is variable and low; taking isotretinoin with food increases bioavailability by 2 times. The maximum concentration in blood plasma is reached within 2 to 4 hours. Isotretinoin binds to plasma proteins by 99.9% (mainly albumin).
Isotretinoin is metabolized to form three main metabolites (they are biologically active): 4-oxo-retinoin, tretinoin, 4-oxo-isotretinoin (the main metabolite), and less significant ones, which include glucuronides. Since in vivo tretinoin and isotretinoin are reversibly converted into each other, the metabolism of isotretinoin is associated with the metabolism of tretinoin. By isomerization, approximately 20-30% of the dose of isotretinoin is metabolized. In humans, enterohepatic recirculation may play a significant role in the pharmacokinetics of isotretinoin. During in vitro studies, it was found that cytochrome P450 isoenzymes CYP2C9, CYP2C8, CYP2B6, and CYP3A4 are involved in the metabolism of isotretinoin.
The half-life of isotretinoin is 19 hours, for 4-oxo-isotretinoin is 29 hours. Isotretinoin is excreted in the bile and kidneys in approximately equal amounts.
For rectal and oral use: acne that does not respond to other treatments; severe forms of acne (conglobate, nodular-cystic, acne with the risk of scarring). For topical use: seborrheic dermatitis, acne vulgaris, perioral dermatitis, rosacea.
Hypersensitivity; for rectal use and ingestion: pregnancy, planned or established (possibly embryotoxic and teratogenic effects), breastfeeding period, hypervitaminosis A, hepatic failure, concomitant tetracyclines, severe hyperlipidemia; additionally for rectal use: rectal pathology; for local use: it is not recommended to apply the drug to large areas of the skin during pregnancy, breastfeeding and women planning pregnancy.
Isotretinoin is used internally, rectally, externally. The dosage regimen is set individually because the adverse reactions and therapeutic efficacy of isotretinoin depend on the dose and vary from patient to patient. Inside is taken with meals, the initial dose is 0.4 – 0.5 mg/kg per day, which is divided into two parts, is used for 16 – 24 weeks.
In case of damage to the trunk or severe course of the disease – 2 mg/kg per day. In severe chronic renal failure, the initial dose should be reduced to 10 mg per day. Depending on the severity of adverse reactions and/or response to treatment, the dose is adjusted. If in 16 – 24 weeks the number of rashes has decreased by 70% or more, then the therapy is stopped.
A repeated course of treatment is carried out upon confirmation of a recurrent or persistent course of the disease with an interval of at least 2 months. Rectally administered 1 time a day at night 0.5-1 mg / kg. Outwardly: for rosacea and acne, apply a solution 2 times a day with a cotton swab or a thin layer of ointment on previously cleansed skin; the duration of therapy is 4 – 12 weeks; after consulting a doctor, a second course is possible.
During treatment, it is necessary to control the content of glucose, lipids, and the functional state of the liver. For patients with diabetes mellitus, more frequent monitoring of blood glucose levels is recommended. Women of reproductive age need to use reliable contraception for 1 month before, during, and for 1 month after the end of therapy. If pregnancy occurs for medical reasons, it must be terminated. With the development of colitis, symptoms of pseudotumor of the brain, visual impairment, therapy is canceled. Neurological examination is necessary if a pseudotumor of the brain is suspected.
You should not prescribe isotretinoin to patients who receive other drugs from the retinoid group in order to avoid hypervitaminosis A. You should avoid increased insolation, including ultraviolet treatment. During therapy with isotretinoin, the tolerance of contact lenses may decrease. Patients who wear contact lenses should use glasses if they develop side reactions from the eyes. Do not apply the drug to mucous membranes. Do not apply the ointment to the skin with severe acute inflammation and around the eyes.
Systemic effects. Sensory organs and nervous system: headache, excessive fatigue, seizures, increased intracranial pressure (pseudotumor of the brain: nausea, headache, vomiting, optic nerve edema, visual impairment), xerophthalmia, photophobia, isolated cases of visual impairment, dark adaptation (decrease in the acuity of twilight vision), rarely – psychosis, depression, suicidal thoughts, lenticular cataract, color vision disorder (disappears after drug withdrawal), keratitis, conjunctivitis, blepharitis, optic neuritis, eye irritation, hearing impairment at certain sound frequencies; digestive system: bleeding from the gums, dryness of the oral mucosa, bleeding, inflammation of the gums, diarrhea, nausea, inflammatory bowel disease (ileitis, colitis), pancreatitis, there are rare cases of fatal pancreatitis, a reversible and transient increase in the activity of liver transaminases, hepatitis ;
hematopoiesis: decreased hematocrit, anemia, leukopenia, decreased or increased platelet count, neutropenia, accelerated erythrocyte sedimentation rate; respiratory systems: rarely – bronchospasm (more often in patients who have a history of bronchial asthma);
musculoskeletal system: joint pain, muscle pain with or without an increase in serum CPK, hyperostosis, calcification of tendons and ligaments, arthritis, tendonitis; skin: peeling of the skin of the soles and palms, itching, rash, erythema of the face / dermatitis, pyogenic granuloma, sweating, paronychia, increased growth of granulation tissue, onychodystrophy, reversible hair loss, persistent thinning of hair, fulminant forms of acne, skin hyperpigmentation, mild hirsutism, photosensitivity, at the beginning of therapy, acne may worsen, which persists for several weeks; effects that are caused by hypervitaminosis A: dryness of the mucous membranes, including lips (cheilitis), skin, nasal cavity (bleeding), pharynx and larynx (hoarseness), eyes (reversible corneal opacity, conjunctivitis and contact lens intolerance); others: hematuria, lymphadenopathy, proteinuria, systemic hypersensitivity reactions, vasculitis (allergic vasculitis, Wegener’s granulomatosis), glomerulonephritis, systemic or local infections caused by gram-positive pathogens (Staphylococcus aureus), a decrease in lipid cholesterolemia, hypertriglyceridemia, high density.
For external use: new rashes from the 2nd week of therapy, which do not require discontinuation of the drug, passing redness of the skin, allergic reactions; possible (with prolonged use) – conjunctivitis, cheilitis, peeling, and dry skin.
The joint use of isotretinoin with other retinoids (including acitretin, retinol, tretinoin, adapalene) increases the likelihood of developing hypervitaminosis A. Since tetracyclines increase the likelihood of intracranial hypertension, joint use with isotretinoin is contraindicated (there are reports of several cases of pseudotumor of the brain). The combined use of isotretinoin with drugs that increase photosensitivity (including tetracyclines, sulfonamides, thiazide diuretics) increases the likelihood of sunburn. The effect of progesterone can weaken isotretinoin, therefore, during therapy with isotretinoin, you should not use contraceptives that contain small doses of progesterone. The effect of isotretinoin ointment is weakened by the combined use of antibiotics of the tetracycline group, as well as the local use of glucocorticosteroids.
Restrictions on use
For systemic use: a history of depression, diabetes mellitus, obesity, alcoholism, lipid metabolism disorders.
Application during pregnancy and lactation
The use of isotretinoin is contraindicated in pregnancy (embryotoxic and teratogenic effects). During therapy with isotretinoin, breastfeeding must be stopped.
In case of an overdose with isotretinoin, symptoms of hypervitaminosis A may develop. It is necessary: gastric lavage in the first few hours after the overdose.
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