Prescription Drugs

CLINICAL PHARMACOLOGY Although the precise mechanism of anthralin's anti-psoriatic action is not fully understood, in vitro evidence suggests that its antimitotic effect results from inhibition of DNA synthesis. Additionally, the chemically reducing properties of anthralin may upset oxidative metabolic processes, providing a further slowing down of epidermal mitosis. Absorption in man has not been finally determined, but in a limited clinical study of anthralin cream, no traces of anthraquinone metabolites were detected in the urine of subjects treated; however, caution is advised in patients with renal disease.

Dritho-Scalp® (anthralin) Topical Cream Important Information about Dritho-Scalp® Warning - Dritho-Scalp® can cause severe irritation. Be careful to keep off skin not affected by psoriasis. Rinse immediately after 5 minutes or the amount of time your doctor prescribed. If irritation occurs, discontinue use and call your doctor. Keep away from eyes. Caution - Dritho-Scalp® can permanently stain clothing and bathroom fixtures. Dritho-Scalp will also stain skin, but skin staining is temporary. Use only old clothing and old towels and linens when using Dritho-Scalp. Any clothing or linens that come in contact with Dritho-Scalp may become permanently stained. Rinse all bathroom fixtures immediately and thoroughly. DESCRIPTION Dritho-Scalp® is a pale yellow topical cream containing 0.5% anthralin USP in a base of white petrolatum, mineral oil, sodium lauryl sulfate, cetostearyl alcohol, ascorbic acid, salicylic acid, methylparaben and purified water. The chemical name of anthralin is l,8-dihydroxy-9- anthrone. The structural formula is:

INDICATIONS An aid in the topical treatment of quiescent or chronic psoriasis of the scalp. Treatment should be continued until the skin is entirely clear, i.e., when there is nothing to feel with the fingers and the texture is normal. DOSAGE AND ADMINISTRATION Generally, it is recommended that Dritho-Scalp be applied once a day or as directed by a physician. Anthralin is known to be a potential skin irritant. The irritant potential of anthralin is directly related to each patient's individual tolerance. Therefore, where the response to anthralin treatment has not previously been established, always commence treatment using a short contact time of 5 to 10 minutes for at least one week using Dritho-Scalp. Contact time can be increased stepwise to twenty to thirty minutes, or as directed by a physician, before removing the cream by thoroughly washing or showering. Apply as directed by a physician. The optimal period of contact will vary according to the patient's response to treatment. To open the tube, unscrew the cap and invert to pierce the membrane. Comb the hair to remove scalar debris and, after suitably parting, apply Dritho-Scalp only to the lesions and rub in well, taking care to prevent the cream spreading onto the forehead. Keep Dritho-Scalp well away from the eyes. Avoid application of the cream to uninvolved scalp margins. Remove any unintended residue which may be deposited behind the ears. At the end of each period of contact, wash the hair and scalp to remove any surplus cream (which may have become red/brown in color). Always wash hands thoroughly after use. Store at controlled room temperature, 15-30C (59-86F). HOW SUPPLIED 50 g tube Manufacturer details: n/a

OVERDOSE No information provided. CONTRAINDICATIONS In patients with acute psoriatic eruptions or a history of hypersensitivity to any of the ingredients.

SIDE EFFECTS Very few instances of contact allergic reactions to anthralin have been reported. However, transient primary irritation of uninvolved skin surrounding the treated lesions is more frequently seen and may occasionally be severe. Application of Dritho-Scalp must be restricted to the psoriatic lesions. If the initial treatment produces excessive soreness or if the lesions spread, reduce frequency of application and, in extreme cases, discontinue use and consult physician. Some temporary discoloration of hair and fingernails may arise during the period of treatment but should be minimized by careful application. Dritho-Scalp may stain skin, hair or fabrics. Staining of fabrics may be permanent, so contact should be avoided. DRUG INTERACTIONS No information provided.

WARNINGS Avoid contact with the eyes or mucous membranes. Dritho-Scalp should not normally be applied to intertriginous skin areas and high strengths should not be used on these sights. Remove any unintended residue which may be deposited behind the ears. Avoid applying to the folds and creases of the skin. Discontinue use if a sensitivity reaction occurs or if excessive irritation develops on uninvolved skin areas. Keep out of the reach of children. PRECAUTIONS For external use only. Dritho-Scalp may stain the hair and should be applied sparingly and carefully to psoriatic lesions only. Contact with fabrics, plastics and other materials may cause staining and should be avoided. To prevent the possibility of discoloration, always rinse the bath/shower with hot water immediately after washing/showering and then use a suitable cleanser to remove any deposit on the surface of the bath or shower. Always wash hands thoroughly after use, 15-30° C (59-86° F). Long-term studies in animals have not been performed to evaluate the carcinogenic potential of the drug. Although anthralin has been found to have tumor-promoting properties on mouse skin, there have been no reports to suggest carcinogenic effects in humans after many years of clinical use. As long-term use of topical corticosteroids may destabilize psoriasis, and withdrawal may also give rise to a 'rebound' phenomenon, an interval of at least one week should be allowed between the discontinuance of such steroids and the commencement of Dritho-Scalp therapy. Petrolatum or a suitably bland emollient may usefully be applied during the intervening period. Pregnancy Pregnancy Category C. Animal reproduction studies have not been conducted with Dritho-Scalp. It is also not known whether Dritho-Scalp can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Dritho-Scalp should be given to a pregnant woman only if clearly needed. Nursing Mothers It is not known whether this drug is excreted in human milk. Because many drugs are excreted in milk and because of the potential for tumorigenicity shown for anthralin in animal studies, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Pediatric Use Safety and effectiveness in pediatric patients have not been established.