目前購物車內沒有商品
維生素A醇
Retinoic Acid
The compound also known as tretinoin, vitamin A acid or vitamin acid should be designated retinoic acid.
DESCRIPTION:
Retin-A Micro (tretinoin gel) microsphere, is a formulation containing , by weight, tretinoin for topical treatment of acne vulgaris. This formulation uses patented methyl methacrylate/glycol dimethacrylate crosspolymer porous microspheres (MICROSPONGE System) to enable inclusion of the active ingredient, tretinoin, in an aqueous gel. Other components of this formulation are purified water, carbomer , carbomer , glycerin, disodium EDTA, propylene glycol, sorbic acid,glucose ether distearate, cyclomethicone and dimethicone copolyol, benzyl alcohol, trolamine, and butylated hydroxytoluene.
Chemically, tretinoin is all- trans -retinoic acid, also known as dimethy traenoic acid. It is a member of the retinoid family of compounds, and a metabolite of naturally occurring Vitamin A. Tretinoin has a molecular weight . Tretinoin has the following structure:
Tretinoin is a retinoic acid (vitamin A) drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel (brand name Retin-A). It is used by some as a hair loss treatment.
Chemical structure of tretinoin.
Derivatives of retinal A compound derived from retinal is named either as an aldehyde derivative as a compound substituted by the bivalent radical retinylidene For example retinal oxime and N6-retinylidene-L-lysine.
Derivatives of retinoic acid Derivatives of retinoic acid named as carboxylic acid derivatives following For example ethyl retinoate and 1-O-retinoyl-b-D-glucopyranuronic acid.
Didehydroretinol (also known as dehydroretinol)
Clinical Pharmacology:
Although the exact mode of action of tretinoin is unknown, current evidence suggests that topical tretinoin decreases cohesiveness of follicular epithelial cells with decreased microcomedo formation. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells causing extrusion of the comedones.
Tretinoin is a retinoid metabolite of Vitamin A that binds to intracellular receptors in the cytosol and nucleus, but cutaneous levels of tretinoin in excess of physiologic concentrations occur following application of a tretinoin-containing topical drug product.
Although tretinoin activates three members of the retinoid acid nuclear receptors which may act to modify gene expression, subsequent protein synthesis, and epithelial cell growth and differentiation, it has not been established whether the clinical effects of tretinoin are mediated through activation of retinoic acid receptors, other mechanisms, or both.
Mode of Action:
Although the exact mode of action of tretinoin is unknown, current evidence suggests that the effectiveness of tretinoin in acne is due primarily to its ability to modify abnormal follicular keratinization. Comedones form in follicles with an excess of keratinized epithelial cells. Tretinoin promotes detachment of cornified cells and the enhanced shedding of corneocytes from the follicle. By increasing the mitotic activity of follicular epithelia, tretinoin also increases the turnover rate of thin, loosely-adherent corneocytes. Through these actions, the comedo contents are extruded and the formation of the microcomedo, the precursor lesion of acne vulgaris, is reduced.
Additionally, tretinoin acts by modulating the proliferation and differentiation of epidermal cells. These effects are mediated by tretinoin's interaction with a family of nuclear retinoic acid receptors. Activation of these nuclear receptors causes changes in gene expression. The exact mechanisms whereby tretinoin-induced changes in gene expression regulate skin function are not understood.
Retinoic acid effect on adult islet glucokinase activity
Effect of retinoic acid on glucokinase mRNA levels
Effect of retinoic acid on glucokinase promoter activity
INDICATIONS AND USAGE:
Retin-A Micro (tretinoin gel) microsphere, is indicated for topical application in the treatment of acne vulgaris. The safety and efficacy of the use of this product in the treatment of other disorders have not been established.
CLINICAL STUDIES:
Retin-A Micro (tretinoin gel) microsphere,In two vehicle-controlled studies, Retin-A Micro (tretinoin gel) microsphere applied once daily was significantly more effective than vehicle in reducing the severity of acne lesion counts. The mean reductions in lesion counts from baseline after treatment for weeks are shown in the following table:
|
Mean Percent Reduction In Lesion Counts
|
|||||
|
|
Retin-A Micro (tretinoin gel) |
Vehicle gel |
|
||
|
Study #1 |
Study #2 |
Study #1 |
Study #2 |
|
|
|
Non-inflammatory |
49% |
32% |
22% |
3% |
|
|
Inflammatory |
37% |
29% |
18% |
24% |
|
|
Total lesion counts |
45% |
32% |
23% |
16% |
|
Retin-A Micro (tretinoin gel) microsphere,was also significantly superior to the vehicle in the investigator's global evaluation of the clinical response. In Study , thirty-five percent of patients using Retin-A Micro (tretinoin gel) microsphere, achieved an excellent result, as compared to eleven percent of patients on the vehicle control. In Study , twenty-eight percent of patients using Retin-A Micro (tretinoin gel) microsphere,achieved an excellent result, as compared to nine percent of the patients on the vehicle control.
Retin-A Micro (tretinoin gel) microsphere:In two vehicle-controlled clinical studies, Retin-A Micro (tretinoin gel) microsphere,applied once daily was more effective than vehicle in reducing the acne lesion counts. The mean reductions in lesion counts from baseline after treatment for weeks are shown
Retin-A Micro (tretinoin gel) microsphere, was also superior to the vehicle in the investigator's global evaluation of the clinical response. In Study , fourteen percentof patients using Retin-A Micro (tretinoin gel) microsphere, achieved an excellent result compared to five percent of patients on vehicle control. In Study, nineteen percent of patients using Retin-A Micro (tretinoin gel) microsphere,achieved an excellent result compared to nine percent of patients on vehicle control.
No studies were conducted comparing the efficacy of Retin-A Micro to Retin-A Micro. There is no evidence that Retin-A Micro is more efficacious than Retin-A Micro or that Retin-A Micro is safer than Retin-A Micro.
PRECAUTIONS
General:
l The skin of certain individuals may become excessively dry, red, swollen, or blistered. If the degree of irritation warrants, patients should be directed to temporarily reduce the amount or frequency of application of the medication, discontinue use temporarily, or discontinue use all together. Efficacy at reduced frequencies of application has not been established. If a reaction suggesting sensitivity occurs, use of the medication should be discontinued. Excessive skin dryness may also be experienced; if so, use of an appropriate emollient during the day may be helpful.
l Unprotected exposure to sunlight, including sunlamps, should be minimized during the use of Retin-A Micro (tretinoin gel) microsphere, and patients with sunburn should be advised not to use the product until fully recovered because of heightened susceptibility to sunlight as a result of the use of tretinoin. Patients who may be required to have considerable sun exposure due to occupation and those with inherent sensitivity to the sun should exercise particular caution. Use of sunscreen products and protective clothing over treated areas are recommended when exposure cannot be avoided.
l Weather extremes, such as wind or cold, also may be irritating to patients under treatment with tretinoin.
l Retin-A Micro (tretinoin gel) microsphere,should be kept away from the eyes, the mouth, paranasal creases of the nose, and mucous membranes.
l Tretinoin has been reported to cause severe irritation on eczematous skin and should be used with utmost caution in patients with this condition.
Carcinogenesis,Mutagenesis, Impairment of Fertility:
In a dermal study in which mice were administered formulations of tretinoin, cutaneous squamous cell carcinomas and papillomas in the treatment area were observed in some female mice. These concentrations are near the tretinoin concentration of these clinical formulations . A dose-related incidence of liver tumors in male mice was observed at those same doses. The maximum systemic doses associated with the administered formulations are and. respectively. These doses are two and four times the maximum human systemic dose applied topically, when normalized for total body surface area. The biological significance of these findings is not clear because they occurred at doses that exceeded the dermal maximally tolerated dose of tretinoin and because they were within the background natural occurrence rate for these tumors in this strain of mice. There was no evidence of carcinogenic potential when of tretinoin was administered topically to mice times the maximum human systemic dose, normalized for total body surface area). For purposes of comparisons of the animal exposure to systemic human exposure, the maximum human systemic dose applied topically is defined as 1 gram of Retin-A Micro (tretinoin gel) microsphere, applied daily ).
Dermal carcinogenicity testing has not been performed with Retin-A Micro (tretinoin gel) microsphere,
Studies in hairless albino mice suggest that concurrent exposure to tretinoin may enhance the tumorigenic potential of carcinogenic doses of UVB and UVA light from a solar simulator. This effect has been confirmed in a later study in pigmented mice, and dark pigmentation did not overcome the enhancement of photocarcinogenesis tretinoin. Although the significance of these studies to humans is not clear, patients should minimize exposure to sunlight or artificial ultraviolet irradiation sources.
The mutagenic potential of tretinoin was evaluated in the Ames assay and in the in vivo mouse micronucleus assay, both of which were negative.
The components of the microspheres have shown potential for genetic toxicity and teratogenesis. EGDMA, a component of the excipient acrylates copolymer, was positive for induction of structural chromosomal aberrations in the in vitro chromosomal aberration assay in mammalian cells in the absence of metabolic activation, and negative for genetic toxicity in the Ames assay, the HGPRT forward mutation assay, and the mouse micronucleus assay.
In dermal Segment I fertility studies of another tretinoin formulation in rats, slight (not statistically significant) decreases in sperm count and motility were seen at times the maximum human systemic dose applied topically, and normalized for total body surface area), and slight (not statistically significant) increases in the number and percent of nonviable embryos in females treated with(times the maximum human systemic dose applied topically and normalized for total body surface area) and above were observed. In oral Segment I and Segment III studies in rats with tretinoin, decreased survival of neonates and growth retardation were observed at doses in excess of (times the human topical dose normalized for total body surface area).
Dermal fertility and perinatal development studies with Retin-A Micro (tretinoin gel) microsphere, have not been performed in any species.
ADVERSE REACTIONS
Irritation Potential:
Acne clinical trial results: In separate clinical trials for each concentration, acne patients treated with Retin-A Micro (tretinoin gel) microsphere,analysis over the twelve week period showed that cutaneous irritation scores for erythema, peeling, dryness, burning/stinging, or itching peaked during the initial two weeks of therapy, decreasing thereafter.
Approximately half of the patients treated with Retin-A Micro,had cutaneous irritation at Week. Of those patients who did experience cutaneous side effects, most had signs or symptoms that were mild in severity (severity was ranked on a ordinal scale:and severe). Less than of patients experienced moderate cutaneous irritation and there was no severe irritation at Week .
In studies on Retin-A Micro (tretinoin gel) microsphere,throughout the treatment period the majority of patients experienced some degree of irritation (mild, moderate, or severe) withof patients having scores indicative of a severe irritation rating; and of patients treated with Retin-A Micro (tretinoin gel) microsphere,discontinued treatment due to irritation, which included dryness in one patient and peeling and urticaria in another.
In studies on Retin-A Micro (tretinoin gel) microsphere,no more than of patients had cutaneous irritation scores indicative of a severe irritation rating; although,of patients treated with Retin-A Micro (tretinoin gel) microsphere,discontinued treatment due to irritation. Of these patients, four had severe irritation after days of treatment, with blistering in one patient.
Results in studies of subjects without acne:In a half-face comparison trial conducted for up to days in women with sensitive skin, but without acne, Retin-A Micro (tretinoin gel) microsphere,was statistically less irritating than tretinoin cream. In addition, a cumulative day irritation evaluation in subjects with normal skin showed that Retin-A Micro (tretinoin gel) microsphere,had a lower irritation profile than tretinoin cream,The clinical significance of these irritation studies for patients with acne is not established. Comparable effectiveness of Retin-A Micro (tretinoin gel) microsphere,and tretinoin cream,has not been established. The lower irritancy of Retin-A Micro (tretinoin gel) microsphere,subjects without acne may be attributable to the properties of its vehicle. The contribution to decreased irritancy by the System has not been established. No irritation studies have been performed to compare Retin-A Micro (tretinoin gel) microsphere,with either Retin-A Micro (tretinoin gel) microsphere,or tretinoin cream,
The skin of certain sensitive individuals may become excessively red, edematous, blistered, or crusted. If these effects occur, the medication should either be discontinued until the integrity of the skin is restored, or the medication should be adjusted to a level the patient can tolerate. However, efficacy has not been established for lower dosing frequencies.
True contact allergy to topical tretinoin is rarely encountered. Temporary hyper- or hypopigmentation has been reported with repeated application of tretinoin. Some individuals have been reported to have heightened susceptibility to sunlight while under treatment with tretinoin.
What is tretinoin topical?
Tretinoin is a topical form of vitamin A. It helps the skin to renew itself more quickly and therefore reduces pimple and blackhead formation, and may improve the appearance and texture of skin.
The Retin-A and Avita brands of tretinoin topical are used to treat acne. The Renova brand of tretinoin topical is used to reduce the appearance of fine wrinkles and mottled skin discoloration, and to make rough facial skin feel smoother.
Tretinoin topical may also be used for purposes other than those listed in this medication guide.
How should I use tretinoin topical?
Clean and pat dry the area of skin where you will apply tretinoin topical. Applying tretinoin topical to wet skin may cause skin irritation. If you are using Renova, wait approximately minutes after washing your face before applying the medication. Apply a light covering of the cream, gel, or solution to the area.
Do not wash the treated area for at least 1 hours after applying tretinoin topical. Avoid the use of any topical products on the treated area for at least hour following application of this medication.
Application of an excessive amount of the tretinoin gel may result in "pilling" of the medication. This does not reduce the effectiveness of the medication, but if pilling occurs, you should use less medication with the next application.
Tretinoin topical should be used as part of a comprehensive skin care and sunlight avoidance program that includes the use of effective sunscreens (minimum SPF) and protective clothing.
Do not stop using tretinoin topical if you do not see improvement in your condition immediately. Treatment with tretinoin topical may be necessary for weeks or months before improvement is seen. If you are using tretinoin topical to treat acne, a temporary worsening of acne may occur at the start of therapy. Using more tretinoin topical or applying it more frequently than prescribed will not make it work any faster, and it may increase side effects. Check with your doctor if skin irritation becomes severe or if the acne does not improve within to weeks.
Store tretinoin topical at room temperature away from moisture and heat. The gel formulations of Retin-A are flammable, keep them away from open flame.
I. Definition:
Tretinoin skin preparations are a family of drugs all similar to Vitamin A. In general, tretinoin gels are stronger than tretinoin creams because the medicine penetrates better when in a gel form. Tretinoin is used to treat acne and aged, sun damaged skin. Tretinoin works best when used in combination with alpha hydroxyacid preparations. If used over a period of years, tretinoin will continue to reverse aging of the skin and can continue improving the skin’s appearance even ten years after starting treatment.
A study in the Archives of Dermatology, May 1996, shows that tretinoin significantly improves the appearance of early stretch marks. Tretinoin works best on stretch marks that are new or enlarging.
II. Action:
l Unplugs acne follicles and brings acne pimples (comedones) to the surface. This is why tretinoin makes acne look worse in the first few weeks of treatment.
l Will reverse some of the changes of photoaging. Causes lightening of brown sun spots and leads to the disappearance of fine lines and wrinkles.
IV. Alternatives:
Acuzine is an all-natural scientific formulation to effectively treat acne and clear the complexion.
V. Safety:
l Tretinoin is very safe when used as directed. Several studies show tretinoin is safe to use during pregnancy, however you should only use tretinoin during pregnancy if this is OK with your obstetrician.
l Do not smoke while applying tretinoin, the gel form is flammable.
VI. How To Use:
l You should wash your face twice a day with a mild non-soap cleanser such as Cetaphil lotion available at your local pharmacy. Pat skin dry with a towel. Let your face dry for minutes before applying tretinoin. Apply one pea size drop to the face each night before bed; do not get the medication into your eyes. One pea size drop should be enough to cover the entire face.
l Apply a moisturizer containing a sunscreen of 15 or higher to the skin each morning or an alpha hydroxyacid preparation. This will help counteract the dryness and scaling. Avoid sun exposure between when the sun's rays are the strongest.
l If the skin becomes too red and dry, decrease the application of Retin-A to every other night or even every third night.