isotretinoin

Isotretinoin

Systematic (IUPAC) name
(13cis)-retinoic acid
Identifiers
CAS number	4759-48-2
ATC code	D10AD04
PubChem	5282379
DrugBank	APRD00140
ChemSpider	4445539
Chemical data
Formula	C20H28O2
Mol. mass	300.44 g/mol
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	Variable
Protein binding	99.9%
Metabolism	Hepatic
Half life	10–20 hours
Excretion	Renal and fecal
Therapeutic considerations
Licence data	US FDA:link
Pregnancy cat.	X(AU) X(US)
Legal status	Prescription Only (S4)(AU) POM(UK) ℞-only(US)
Routes	Oral, topical
Y(what is this?)  (verify)

Isotretinoin (INN) (pronounced /ˌaɪsoʊtrɨˈtɪnɵʊɨn/^[1]) is a medication used for the treatment of moderate to severe acne. It was first developed to be used as a chemotherapy medication for the treatment of brain cancer, pancreatic cancer and more. It is still used in the treatment of these cancers to this day because of its ability to kill rapidly dividing cells. The effects of the medication are systemic and non-selective. In some cases, it is used to treat Harlequin type ichthyosis, a usually lethal skin deformation in which sufferers develop armor plated-like skin and usually die soon after birth. It is a retinoid, meaning it derives from vitamin A and is found in small quantities naturally in the body. Oral isotretinoin is marketed under various trade names, most commonly Roaccutane (Hoffman-La Roche; simply Accutane before July 2009), Amnesteem (Mylan), Claravis (Barr), Clarus (PremPharm), Decutan (Actavis), Isotane (Pacific Pharmaceuticals), Izotek (BlauFarma), Oratane (Genepharm Australasia), or Sotret (Ranbaxy), while topical isotretinoin is most commonly marketed under the trade names Isotrex or Isotrexin (Stiefel)^[2].

History

An early, effective treatment of acne first used during the 1930s was high doses of the fat-soluble vitamin A (retinoic acid). At these dosage levels (sometimes 500,000 IU per day), sebum production is notably reduced, thwarting acne, but overly dry hair is a negative side effect, and such high doses can lead to vitamin A toxicity.^{[citation needed]}. Use of animal-based vitamin A at nutritive levels (where the upper limit dosage is 10,000 IU daily), taken over the course of a year, has also been shown to reduce acne. One positive side effect is that patients tend to be healthier, as present diets often do not include enough fat-soluble vitamin A.^{[citation needed]}

Building on the discovery that vitamin A is good for the skin, and can reduce sebum production at toxic dosages, the retinoic acid derivative isotretinoin (13-cis-retinoic acid) was developed and released in 1982 by Hoffmann-La Roche. The advantage of the synthetic compound is an overall better success at treating acne^{[citation needed]}. When compared to toxic dosages of Vitamin A, the side effects are reduced.

Dosage requirements of isotretinoin have been disputed. Due to a 1984 study funded by Roche, relatively high dosages of isotretinoin became mainstream in treatment in the United States. Lower dosages were found to be effective in treatment by independent research (see dosage section of this article) in countries outside the U.S., where the funding was through socialized medicine.

From the time of its introduction, the drug was known to have teratogenic potential, and pregnancies with the drug were strongly discouraged. When they occurred, they were found to have approximately 30% rates of congenital malformation, versus a 3-5% baseline risk.^[3] Beginning in 1998, prescriptions of the drug came under scrutiny, as fewer than half of prescribers were testing for pregnancy, usually relying on less sensitive urine tests.^[4] On the grounds that pregnancies by women taking the drug had been underreported by the manufacturer between 1982 and 2000, and that once generic manufacturers entered the market risk management was no longer centralized, the FDA instituted restrictions on prescribing and dispensing the drug, first with the "System to Manage Accutane Related Teratogenicity" (SMART) in 2000, and subsequently the iPLEDGE program in 2006. A retrospective cohort study recently found that pregnancy rates were quite high during the period (1 per 30 women per year), but 84% of pregnancies were ended by induced abortion.^[3]

In February 2002, Roche's patents for isotretinoin expired and there are now many other companies selling cheaper generic versions of the drug. On June 29, 2009 Roche Pharmaceuticals, the original creator and distributor of isotretinoin, officially discontinued both the manufacture and distribution of their Accutane brand in the United States due to what the company described as business reasons related to low market share (below 5 percent) coupled with the high cost of defending personal-injury lawsuits brought by some patients prescribed the drug. Generic isotretinoin will remain available in the United States through various manufacturers. Roche USA continues to defend Accutane and claims to have treated over 13 million patients since its introduction in 1982. F. Hoffmann-La Roche Ltd. apparently will continue to manufacture and distribute Roaccutane outside of America.^[5]

Isotretinoin is available over the internet from countries where it can be dispensed without a prescription. This presents a dilemma for acne sufferers residing in countries with highly regulated medical and pharmaceutical industries (FD&C Act), as private importation might violate existing statutes.

Pharmacodynamics

Isotretinoin's exact mechanism of action is unknown. However, it is thought that similar to other retinoids, the drug alters DNA transcription.^[6] The drug decreases the size and sebum output of the sebaceous glands.^[7] It also stabilizes keratinization, makes the cells that are sloughed off into the sebaceous glands less sticky, and therefore inhibits the formation of comedones.^{[citation needed]} Isotretinoin's combined impact on several of acne's contributory factors distinguishes isotretinoin from alternative remedies such as antibiotics and accounts for its greater efficacy in severe, nodulocystic cases.

The effect on sebum production is temporary.^[8] However, remission of the disease can be "complete and prolonged."^[7][9][10]

Pharmacokinetics

Isotretinoin, when administered orally, is best absorbed when taken after a high fat meal, as it has a high level of lipophilicity. In a crossover study, it was found that the peak plasma concentration more than doubled when taken after a high fat meal versus a fasted condition. Isotretinoin is primarily (99.9%) bound to plasma proteins, mostly albumin. At least three metabolites have been detected in human plasma after oral administration of isotretinoin. These are 4-oxo-isotretinoin, retinoic acid and 4-oxo-retinoic acid. Isotretinoin also oxidizes, irreversibly, to 4-oxo-isotretinoin. The metabolites of isotretinoin are excreted through both urine and feces. The mean elimination half-life is 21 hours, with a standard deviation from this mean of 8.2 hours.

Clinical use

Currently, isotretinoin continues to be used only after other acne treatments fail to produce results. Treatment of acne begins with topical medications (e.g. benzoyl peroxide, adapalene, etc), followed by oral antibiotics (or a combination) and finally isotretinoin therapy. This is because other treatments, while less effective than isotretinoin, are thought to be associated with fewer adverse effects and lower cost. The higher cost is due to the medical supervision required in taking a toxic dosage. The cost of the medicine is also a factor (example: taking 5, 10, or even 20 mg daily is far less expensive than taking 80 mg daily).

Indications

Isotretinoin is indicated for the treatment of severe cystic acne vulgaris.^[11][12] It is also effective for hidradenitis suppurativa and some cases of severe acne rosacea.^[12] It can also be used to help treat harlequin ichthyosis, and is used in xeroderma pigmentosum cases to relieve keratoses. Isotretinoin has been used to treat the extremely rare condition Fibrodysplasia Ossificans Progressiva.

It is also used for treatment of neuroblastoma, a form of brain cancer.

Prescribing restrictions

In the United Kingdom, this drug may only be prescribed by, or under the supervision of, a consultant dermatologist.^[13] Because severe, cystic acne has the potential to cause permanent scarring over a short period, restrictions on isotretinoin's more immediate availability have proved contentious.^[14] Similar restrictions are common in most Australian states – in New South Wales and Victoria, for instance, the prescriber must be a Fellow of the Australasian College of Dermatologists (FACD).^[15] In New Zealand, isotretinoin can be prescribed by any doctor but is subsidised only if prescribed by a vocationally registered general practitioner or dermatologist.

Since 1 March 2006, the dispensing of isotretinoin in the United States has been controlled by a FDA-mandated website called iPLEDGE – dermatologists are required to register their patients before prescribing and pharmacists are required to check the website before dispensing the drug. The prescription may not be dispensed until both parties have complied. A physician may not prescribe more than a 30-day supply. A new prescription may not be written for at least 30 days. Pharmacies are also under similar restriction. There is also a 7 day window from the time the prescription is written in which the medication must be picked up at the pharmacy. If the original prescription is lost, or pick-up window is missed, the patient must re-qualify to have another prescription written. Doctors and pharmacists must also verify written prescriptions in an online system before patients may fill the prescription.

In at least Mexico and Colombia, this drug is of restricted use, and an official identification and patient signature is required by the pharmacies.

Dosage

10 mg capsule

The dose of isotretinoin a patient receives is dependent on their weight and the severity of the condition. High dose treatments are administered between 0.5 mg/kg/day to 2 mg/kg/day (usually at 0.5 to 1 mg/kg/day^[16], divided into two doses), for a total treatment of 4–6 months. A second course may be used two months following the cessation of the initial course if severe acne recurs. Efficacy appears to be related to the cumulative dose of isotretinoin taken, with a total cumulative dose of 120–150 mg/kg used as a guideline.^[11][12] High dose treatments should only be used as a last resort due to adverse side effects.

Other studies show that lower dosage treatments, such as 10-20mg/day (approximately half the high dosage treatments above), are just as effective, with diminished or non-perceptible side effects.^{[17][18][19][20][21][22][23]}

Preparations

Isotretinoin is marketed under many brand names by various manufacturers. It is typically available as 5 mg, 10 mg, 20 mg, 30 mg and (in the USA) 40 mg capsules. Some brands of oral isotretinoin include: Accure (Alphapharm), Accutane and Roaccutane (Roche), Aknenormin (Hermal), Amnesteem (Mylan), Ciscutan (Pelpharma), Claravis (Barr), Clarus (Prepharm), Isohexal (Hexal Australia), Istretinoin-A (Pharmathen), Isosupra (SMB Laboratories), Isotane (Pacific Pharmaceuticals), Isotroin (Cipla), Oratane (Douglas Pharmaceuticals), Atretin (Lafrancol), Nimegen (Medica Korea) , and Sotret (Ranbaxy).

It is also available as a 0.05% topical preparation, marketed by Stiefel under the trade name Isotrex or Isotrexin (with erythromycin).

Adverse effects

Increasingly higher dosages will result in higher toxicity, resembling vitamin A toxicity.

Adverse drug reactions associated with isotretinoin therapy include:

• Common: Mild acne flare, dryness of skin, lips and mucous membranes, infection of the cuticles, cheilitis, itch, rosacea, skin fragility, skin peeling, rash, flushing, nose bleeds, dry eyes, diffuse alopecia areata, eye irritation, conjunctivitis, reduced tolerance to contact lenses, hyperlipidaemia, raised liver enzymes, permanent thin skin, headaches, permanent hair thinning (This could start or continue after treatment), myalgia and/or arthralgia, back pain.

• Infrequent: severe acne flare, raised blood glucose level, increased erythrocyte sedimentation rate, fatigue.

• Rare: impaired night vision; cataracts; optic neuritis; menstrual disturbances; inflammatory bowel disease; pancreatitis; hepatitis; corneal opacities; papilloedema; idiopathic intracranial hypertension; skeletal hyperostosis; extraosseous calcification; psychosis; and it is believed that severe depression can occur, although there is no conclusive evidence for this.

The following adverse effects have been reported to persist, even after discontinuing therapy: alopecia (hair loss), arthralgias, decreased night vision, inflammatory bowel disease, degenerative disc disease, keloids, bone disease. High dosages of isotretinoin have been reported to cause rosacea (a disease of severe facial skin redness and irritation).

Erectile dysfunction in the form of difficulty in maintaining erection was reported in several patients in a clinical study. Although the definitive cause remains unknown, the impotence may have been caused by the psychiatric side effects of isotretinoin as it was seen to occur alongside with symptoms of depression.^[24]

While vitamin E supplements have been advocated by some to reduce the toxicity of high-dose retinoids without reducing drug efficacy, test results have proven this to be false (though no indication of what form of vitamin E was used).^[25]

Patients with degenerative conditions, such as muscular dystrophy, should not take isotretinoin as it may exacerbate and/or accelerate the underlying condition. This may be due to a suspected effect similar to accelerated aging on the skin and tissues of the body, including muscle fibers.^{[citation needed]}

Patients receiving isotretinoin therapy are not permitted to donate blood during and for at least one month after discontinuation of isotretinoin therapy due to its teratogenicity.^[26]

Teratogenicity (Birth Defects)

Isotretinoin is a teratogen and is highly likely to cause birth defects if taken during pregnancy. A few of the more common birth defects that this drug can cause are hearing and visual impairment, missing earlobes, facial dysmorphism, and mental retardation. Isotretinoin is classified as FDA Pregnancy Category X and ADEC Category X, and use is contraindicated in pregnancy.^[12]

The manufacturer recommends that pregnancy be excluded in female patients two weeks prior to commencement of isotretinoin, and that they should use two simultaneous forms of effective contraception at least one month prior to commencement, during, and for at least one month following isotretinoin therapy.^[27]

In the U.S. more than 2,000 women have become pregnant while taking the drug between 1982 and 2003, with most pregnancies ending in abortion or miscarriage. About 160 babies with birth defects were born. Consequently, the iPLEDGE program was introduced by the U.S. Food and Drug Administration on 12 August 2005 in an attempt to ensure that female patients receiving isotretinoin do not become pregnant – as of 1 March 2006, only prescribers registered and activated in iPLEDGE are able to prescribe isotretinoin, and only patients registered and qualified in iPLEDGE will be able to have isotretinoin dispensed. The iPLEDGE program also applies to males, even though there has been no evidence of isotretinoin excretion through seminal fluids.

Depression

Several studies have suggested a possible link between isotretinoin and clinical depression.^[28][29] Various case reports of depression, suicidal ideation, suicide attempt, and suicide in patients treated with isotretinoin have been reported to the U.S. FDA Adverse Events Reporting System, with 431 cases reported between 1982 and May 2001 – of these, 37 patients had committed suicide.^[30] This suicide rate is in line with national rates and does not exceed the national average. While some analyses have suggested an association between patients receiving isotretinoin therapy and depression, no causal relationship has been established and further studies are required.^[31][32]

Studies have shown that patients with acne, the population group eligible to receive isotretinoin therapy, have an increased risk of clinical depression compared with the general population.^[33][34] Chee Hong describes Isotretinoin-related depression as "an idiosyncratic side-effect", claiming, often anxiety can bring on acne and depression, creating more anxiety.^[35] Correspondingly, treatment of severe acne with isotretinoin has been shown to reduce anxiety and depression, for tests have shown acne to be a main depressant in most tested patients' lives.^[36][37]

One study utilising positron emission tomography (PET) showed functional brain imaging changes in patients treated with isotretinoin but showed no changes in depressive state in the patients that could be measured with the Hamilton depression scale.^[38]

U.S. Representative Bart Stupak (D-MI) believes unadvertised psychological side effects from the drug drove his teenage son, Bartholomew Thomas Stupak Jr., to commit suicide in 2000.

Crohn's Disease and Ulcerative Colitis

Several scientific studies have posted that isotretinoin is a possible cause of Crohn's Disease and Ulcerative colitis in some individuals. Three cases in the United States have gone to trial thus far, with all three resulting in multi-million dollar judgments against the makers of isotretinoin; there are an additional 425 cases pending. [1] ^{[39] [40] [41]} [2]

Drug interactions

The concurrent use of isotretinoin with tetracycline antibiotics or vitamin A supplementation is not recommended. Concurrent use of isotretinoin with tetracyclines significantly increases the risk of idiopathic intracranial hypertension. Concurrent intake of Vitamin A supplementation increases the risk of vitamin A toxicity.^[12]

Concurrent use of isotretinoin with methotrexate increases the risk of hepatotoxicity and may increase methotrexate levels. The combination is used with caution and close monitoring of adverse effects and liver function tests.^[11]

See also

• Hypervitaminosis A syndrome

References

External links

• Hoffmann-La Roche (Makers of (Ro) accutane)
• FDA's Accutane Information Page
• FDA distributed "Accutane Medication Guide"
• Drugs.com Isotretinoin Information
• Dermatology Vol 9: issue 5: Night blindness, vitamin A deficiency, and isotretinoin psychotoxicity
• DermNet treatments/isotretinoin

• Practical Guide to Accutane Side Effects, vitminA.org