Coal tar ointments

Calculate the percentage (w/w) of coal tar in the finished product when 8 grams of coal tar is mixed with 120 g of a 4% coal tar ointment. 

In what proportion should a 20% coal tar ointment be mixed with white petrolatum (diluent) to produce a 2% coal tar ointment ... 

A pharmacist has on hand one kg of a 5% coal tar ointment and 4 lb (avoir) of a 10% coal tar ointment. (A) What is the concentration of coal tar in the finished product, if the two ointments are mixed (B) How many grams of coal tar should be added to the product to obtain an ointment containing 20% of coal tar ... 

Drinking chaparral tea may result in exposure to wood creosote by swallowing. If you drink chaparral tea you may expose your children. Creosote is also found in coal tar shampoos used for anti-dandruff therapy, in coal tar ointments used for treatment of eczematous dermatitis and in mineral coal tar for the treatment of psoriasis. You may expose your children to creosote if... 

Urine samples collected from 43 patients being treated in the hospital for psoriasis with a coal tar ointment and from 37 controls who had never been treated with coal tar were analyzed for the presence of 1-hydroxypyrene-glucuronide and r-7,t-8,t-9,c-10-tetrahydroxy-7,8,9,10-tetrahydro-benzo[a]pyrene (Bowman et al. 1997). The metabolite, r-7,t-8,t-9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene, was detected in urine of 20 (47%) of the patients, but only 4 (10%) of the controls. The other metabolite studied, 1-hydroxypyrene-glucuronide, was detected in all samples, but the mean level for patients was 40.96 72.62 pmol pmol 1 creatinine and that for controls was 0.38 0.32 pmol pmol"1 this difference was significant (PO.OOOl). The ratio of urinary levels of the two metabolites was examined in the coal tar-treated patients and found to vary by approximately 6,000-fold, suggesting wide variation between individuals in the ability to metabolize benzo[a]pyrene and pyrene. 

Similar results were obtained in another study of psoriasis patients (43 patients and 39 untreated controls) being treated with a coal tar ointment (Weston et al. 1994). The benzo[a]pyrene metabolite, r7,t8,t9,cl0-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene, was detected in urine of 18 psoriasis patients (42%) and 4 untreated subjects (10%). There was a significant difference in the levels of r7,t8,t9,cl0-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene in patients and untreated individuals with levels varying from undetectable to 330 finol/mL for patients and from undetectable to 40 finol/mL for untreated individuals. A second metabolite 1-hydroxypyrene-glucuronidide was found in all urine samples, but levels were significantly higher in psoriasis patients than in untreated controls, ranging from 180 to 50,000 finol/mL in patients and 36-650 finol/mL in untreated individuals. 

Sarto et al. (1989) examined the excretion of coal tar metabolites in male psoriatic patients treated dermally with an ointment containing 2 or 4%, or pure coal tar on 35-60% of the surface skin for 1-13 days. Coal tar content was reported to be 0.49 mg/g for the 4% coal tar ointment, and about... 

Bowman ED, Rothman N, Hackl C, et al. 1997. Interindividual variation in the levels of certain urinary polycyclic aromatic hydrocarbon metabolites following medicinal exposure to coal tar ointment. Biomarkers 2 321-327. 

McGarry GW, Robertson JR. 1989. Scrotal carcinoma following prolonged use of crude coal tar ointment. Br J Urol 63 (2) 211. 

COAL TAR NAPHTHA or COAL TAR OIL, HEAVY DISTILLATE (8030-30-6) Highly flammable liquid. Forms explosive mixture with air [explosion limits in air (vol %) 1.0 to uel unknown flash point 100 to 107°F/37 to 42°C Fire Rating 2]. Violent reaction with strong oxidizers concentrated nitric acid. Incompatible with strong acids, nitrates. May attack some plastics, mbber, and coatings. On small fires, use dry chemical powder (such as Purple-K-Powder), foam, or CO2 extinguishers. COAL TAR OIL or COAL TAR, BROWN or COAL TAR EXTRACT or COAL TAR OINTMENT (8007-45-2 69912-81-8 91722-33-7 101316-83-0) see tar, liquid. 

Tumorigenidty Occupational and animal studies have shown an increased risk of cancer after exposure to coal tar, which contains several carcinogenic compounds, but the risk of cancer is unclear. In 13200 patients with psoriasis and eczema, proportional hazards regression was used to evaluate differences in cancer risks [5. Patients who used coal tar ointments were compared with patients who used topical glucocorticoids. The median duration of exposure was 6 (range 1-300) months. Coal tar did not increase the risk of non-skin malignancies (HR=0.92 95% Cl = 0.8, 1.1) or the risk of skin cancers (HR= 1.1 95% CI=0.69,1.7). 

Many active ingredients of ointments and lotions are not readily dispersible because of their insolubility. Coal-tar products are an example which have been successfully blended into ointment bases by the use of surfactants [227]. A 1 % crude coal-tar ointment in which the tar is dispersed by the addition of 0.5 % polysorbate 20 prior to its incorporation in the base, produces fewer adverse skin reactions than the normal preparations without surfactant [228]. Such preparations are also more readily removed from the skin with water. It has been stated, however, that incorporation of coal-tar into hydrophilic ointment bases allows the penetration of carcinogenic components which may be present in the tar. A clear transparent solution of the US Formulary Coal-Tar Solution can be made, provided that 10% polysorbate 20 remains in the final dilution [229]. 

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