Tar

(BAN, rINN)
Synonyms: Alquitrán vegetal; Brea; Brea de pino; Brea vegetal; Goudron Végétal; Nadelholzteer; Pine Tar; Pix Abietinarum; Pix Liquida; Pix Pini; Pyroleum Pini; Wood Tar.
Cyrillic synonym: Древесная Смола; Древесный Дёготь.

💊 Chemical information

Pharmacopoeias.

In Br.

BP 2008

(Tar). A bituminous liquid obtained from the wood of various trees of the family Pinaceae by destructive distillation. It is known in commerce as Stockholm Tar. A dark brown or nearly black semi-liquid with a characteristic empyreumatic odour; it is heavier than water. Soluble in alcohol (90%), in chloroform, in ether, and in fixed and volatile oils. The aqueous liquid obtained by shaking 1 g with 20 mL of water for 5 minutes is acidic to litmus paper.

Storage.

When stored for some time tar separates into a layer which is granular in character due to minute crystallisation of catechol, resin acids, etc. and a surface layer of a syrupy consistence.

💊 Adverse Effects and Precautions

Tars and tar oils may cause irritation and acne-like eruptions of the skin and should not be applied to inflamed or broken skin, mucosa, or the anogenital area. They should be used with caution on the face and skin flexures. Hypersensitivity reactions are rare but wood tars are more likely to cause sensitisation than coal tar. However, unlike wood tars, coal tar has a photosensitising action. Preparations of refined tar products appear to be less likely than crude tars to stain the skin, hair, and clothing. Depending on their composition the systemic effects of tars and tar oils are similar to those for phenol.

Carcinogenicity.

Coal tar and coal tar distillates contain a number of known and potential carcinogens including benzene, naphthalene, and other polycyclic aromatic hydrocarbons.1 Studies of occupational exposure (for example, during coke production, coal gasification, and aluminium production) have found systemic absorption of significant amounts of polycyclic aromatic hydrocarbons,2 and increases in the risks of developing a range of cancers.1,2 Systemic absorption of polycyclic aromatic hydrocarbons has also been measured after the application of coal tar preparations used in the treatment of skin conditions.2 However, although an increased risk of skin carcinoma was found3 in 59 patients with psoriasis who had had very high exposures to tar and/or UV radiation, other cohort studies4-6 found no increase in the risk of developing cancers from coal tar, even after long-term use.
1. National Toxicology Program. Coal tars and coal tar pitches. Rep Carcinog 2002; 10: 68–70
2. van Schooten F-J, Godschalk R. Coal tar therapy: is it carcinogenic? Drug Safety 1996; 15: 374–7
3. Stern RS, et al. Skin carcinoma in patients with psoriasis treated with topical tar and artificial ultraviolet radiation. Lancet 1980; i: 732–5
4. Pittelkow MR, et al. Skin cancer in patients with psoriasis treated with coal tar. Arch Dermatol 1981; 117: 465–8
5. Jones SK, et al. Further evidence of the safety of tar in the management of psoriasis. Br J Dermatol 1985; 113: 97–101
6. Stern RS, Laird N. The carcinogenic risk of treatments for severe psoriasis. Cancer 1994; 73: 2759–64.

Extemporaneous preparation.

Concern about the possible carcinogenic potential of coal tar (see above) led the Health and Safety Executive in the UK to recommend that gloves for chemical protection, as opposed to disposable surgeon’s gloves, should be worn during the extemporaneous preparation of formulations containing coal tar.1
1. Anonymous. Chemical protection gloves recommended for coal tar ointments. Pharm J 1997; 259: 757.

💊 Uses and Administration

Tars and tar oils can reduce the thickness of the epidermis. They are antipruritic and may be weakly antiseptic. They are used topically in eczema, psoriasis (below), dandruff, seborrhoeic dermatitis, and other skin disorders. Coal tar preparations have largely replaced the use of wood tars. Ultraviolet (UVB) light increases the efficacy of coal tar in the treatment of psoriasis. Some wood tars, including creosote have been used in expectorant preparations.

Nonprescription use.

After a review of products for safety and efficacy the FDA ruled that cade oil or tar should not be used in nonprescription shampoos1 and that tar should no longer be included in nonprescription expectorants.2
1. Anonymous. Nonprescription drug review gains momentum. WHO Drug Inf 1991; 5: 62
2. Anonymous. FDA announces standards for nonprescription sleep-aid products and expectorants. Clin Pharm 1989; 8: 388.

Psoriasis.

Coal tar has long been employed in the treatment of psoriasis, and used alone or with dithranol and/or ultraviolet light it continues to be a first-line option, although its use is declining. It is particularly suited to the treatment of stable chronic plaque psoriasis. Its mode of action is unknown but it is considered to have antiproliferative and anti-inflammatory activity, producing a reduction in the thickness of viable epidermis. Crude tar preparations are rather messy and unpleasant; refined products may be more aesthetically acceptable and less likely to stain skin, hair, and clothing although some consider them to be less effective. Treatments usually start with concentrations equivalent to 0.5 to 1% of crude coal tar with the concentration being increased as necessary every few days up to a maximum of 10%. The higher strength preparations may be required for the management of thicker patches of psoriasis but the British Association of Dermatologists considers that coal tar preparations of between 1 and 5% in white or yellow soft paraffin are as effective as higher concentrations, and that the use of higher concentrations, which has been traditionally advocated, has no evidence-based foundation and is best avoided, especially as it restricts outpatient use. Coal tar may not clear psoriasis as fast as other agents but extended periods of remission can be obtained with its use. The Goeckerman regimen utilises the enhanced efficacy obtained when coal tar is applied before exposure to ultraviolet (UVB) light. The mechanism for this effect is not known but it does not appear to be due to the photosensitising action of coal tar. In most regimens the coal tar is applied 2 hours before exposure to UVB light. In Ingram’s regimen and its modifications the use of coal tar and UVB light is followed by topical treatment with dithranol. It has been suggested that the irritant effects of dithranol treatment can be reduced without loss of efficacy if coal tar is also used.
1. Rotstein H, Baker C. The treatment of psoriasis. Med J Aust 1990; 152: 153–64
2. Arnold WP. Tar. Clin Dermatol 1997; 15: 739–44
3. Thami GP, Sarkar R. Coal tar: past, present and future. Clin Exp Dermatol 2002; 27: 99–103
4. British Association of Dermatologists. Psoriasis guideline 2006. Available at: http://www.bad.org.uk/healthcare/guidelines/ psoriasis_guideline_(Final_update)_280906.pdf (accessed 27/09/07)

💊 Preparations

BP 2008: Calamine and Coal Tar Ointment; Coal Tar and Salicylic Acid Ointment; Coal Tar and Zinc Ointment; Coal Tar Paste; Coal Tar Solution; Strong Coal Tar Solution; Zinc and Coal Tar Paste; USP 31: Coal Tar Ointment; Coal Tar Topical Solution; Compound Resorcinol Ointment.

Proprietary Preparations

Arg.: Alcoderm; Alcontar†; Fijacid; Ingeshamp; Ionil-T Plus†; Soriacur†; Sorial; Supertar†; Sutrico Tar; Targel; Austral.: Alphosyl; Exorex†; Ionil-T Plus†; Linotar; Neutrogena T/Gel; Pinetarsol; Polytar Plus; Psorigel†; Austria: Exorex; Braz.: Ionil-T Plus†; Tarflex; Theratar; Canad.: Balnetar; Doak-Oil; Estar†; Mazon Medicated Soap; Neutrogena T/Gel; Neutrogena T/Gel Therapeutic; Pentrax; Spectro Tar†; Targel; Tersa-Tar; Chile: DHS Tar Gel; Neutrogena Shampoo Neutar; Psorigel†; Tarmed; Tigel IRM; Cz.: Delatar; Teer-Linola-Fett N†; Denm.: Basotar†; Fr.: Caditar; Ger.: Basiter†; Berniter; Hoepixin Bad N†; Lorinden Teersalbe; Tarmed; Teer-Linola-Fett; Gr.: Exorex; Ionil; Tarmed; Hong Kong: Pinetarsol; Zetar; Irl.: Alphosyl†; Exorex; Pentrax; Psoriderm; Israel: Alphosyl 2 in 1; Denorex†; T/Gel; Ital.: Konor; Shampoo SDE Tar†; Malaysia: Pin-Xol; Pinetarsol; Mex.: Ionil-T Plus; Shampoo Tersa-Tar†; Tarmed; Neth.: Exorex; Norw.: Soraderm†; NZ: Pinetarsol; Psorigel†; Pol.: Delatar; Freederm Tar; Polytar; Port.: Neutar; Tarmed; Rus.: Freederm Tar (Фридерм Деготь); S.Afr.: Alphosyl; Denorex; Exarex†; Linotar; Singapore: Pinetarsol; Spain: Alfitar; Alphosyl; Piroxgel; Psoriasdin; Tar Isdin Champu; Tarmed; Tejel; UK: Alphosyl 2 in 1; Carbo-Dome; Clinitar; Exorex; Pentrax; Pinetarsol; Psoriderm; T/Gel; USA: Balnetar; Creamy Tar; DHS Tar; Estar†; Fototar; Ionil-T Plus; MG217 Medicated; Neutrogena T/Gel; Oxipor VHC; PC-Tar; Pentrax; Polytar; Psorigel†; Taraphilic; Tegrin; Tera-Gel; Zetar; Venez.: Alma-Tar†. Multi-ingredient: Arg.: Acnetrol; Adop-Tar†; Aeroseb; Champuacid; Cicatrol; Confor-Tar†; Cremsor N; Domtisona†; Eurocoal; Farm-X; Hyaluron; Ingemet; Ionil-T; Laurinol Plus; Medic†; Mencogrin; Mencogrin AP; Oilalfo; Sequals G; Sorsis; Sorsis Beta; Austral.: Alphosyl; Eczema Cream; Egopsoryl TA; ER Cream†; Fongitar; Hamilton Pine Tar with Menthol; IonilT; Neutrogena T/Sal†; Pinetarsol; Polytar; Psor-Asist; Sebitar; Tarband†; Austria: Alphosyl; Alpicort; Locacorten Tar; Belg.: Locacortene Tar†; Braz.: Hebrin; Ionil-T; Polytar; Xarope Sao Joao†; Canad.: Boil Ease†; Dan-Tar Plus; Denorex Medicated; Mazon Medicated Cream; Mazon Medicated Shampoo; Medi-Dan; Multi-Tar Plus; Oxipor; P & S Plus; Polytar; Polytar AF; Sebcur/T; Sebutone†; SJ Liniment; Spectro Tar†; Sterex; Sterex Plus; Tardan; Targel SA; X-Seb T; X-Seb T Plus; X-Tar; Chile: Denorex Herbal†; Ionil-T; Tarytar†; Cz.: Locacorten Tar†; Polytar; Polytar AF; Suspensio Visnevski cum Pice Liquida Herbacos; Fr.: Alphosyl†; Cystel Shampooing Antiseborrheique†; Epiphane†; Item Alphacade; Laccoderme a l’huile de cade; Node DS; Node K; Node P; Novophane; Novophane S; Phytolithe†; Psocortene; Sebosquam; Squaphane; Squaphane E; Squaphane MasqueCreme; Squaphane P; Squaphane S; Ger.: Lorinden T†; Psorigerb N†; Hong Kong: 2-4-2†; Cocois†; Egopsoryl TA; Fongitar; Ionil-T; Locacorten Tar†; Multi-Tar; Polytar; Polytar Emollient; Sebitar; Hung.: Aknefug-liquid N†; Polytar ; Polytar AF; India: Derobin Skin; Ionax T; Indon.: Polytar ; Irl.: Alphosyl HC†; Capasal; Cocois; Denorex; Gelcotar†; Ionil-T†; Polytar; Polytar Emollient†; Pragmatar; Israel: Alphosyl HC†; Alphosyl†; Capasal; CT Ointment†; CT Pommade†; CT Shampoo†; Polytar; Topicorten-Tar; Ital.: Alphosyle†; Balta-Crin Tar†; Rivescal Tar; Malaysia: Cocois†; Egopsoryl TA; Mentar; Polytar; Sebitar; Mex.: Antaderm; Dariseb; Dealan; Dermoscalp; Ionil-T; Jabon del Tio Nacho; Polytar; Sebryl; Sebryl Plus; Sebstopp; Shampoo del Tio Nacho; Neth.: Denorex; NZ: Coco-Scalp; Cocois†; Egopsoryl TA; Fongitar†; Ionil-T; Polytar; Polytar Emollient; Polytar Plus; Sebitar; Philipp.: Fongitar; Ionil-T; Polytar; Pol.: Cocois; Polytar AF; Psorisan; Port.: Alpha Cade; Banholeum Composto; Betacade†; Edoltar†; Fongitar; Polytar ; Sucadermil; S.Afr.: Alphosyl; Fongitar; Haarlemensis; Oxipor VHC; Polytar; SB Universal Ointment; Singapore: Denorex†; Egopsoryl TA; Fongitar; Ionil-T; Polytar; Sebitar; Spain: Alphosyl; Bazalin; Emolytar; Ionil Champu; Ionil†; Polytar; Quinortar†; Tar Isdin Plus†; Zincation Plus; Swed.: Alphosyl†; Switz.: Alphosyl†; Thai.: Fongitar; Ionil-T†; Polytar; Turk.: Kadolin; Wilkinson; UK: Alphosyl HC; Capasal; Cocois; Polytar AF; Polytar Emollient; Polytar Liquid; Polytar Plus; Pragmatar†; Psorin; Sebco; Snowfire; Varicose Ointment; USA: Boil Ease; Ionil-T; Medotar; Neutrogena T/Sal; Sal-Oil-T; Sebex-T; SLT†; Tarlene; Tarsum; X-Seb T; X-Seb T Plus; Venez.: Vitar†.
Published January 21, 2019.