The Use of Tannic Acid in the Local Treatment of Burn Wounds: Intriguing Old and New Perspectives

Wounds. 2001;13(4) 

In This Article

Conclusion

In summary, tannic acid can be considered as one of the more important therapeutics used in the topical treatment of burn patients throughout the 20th century. Its use, however, changed dramatically over time, and many positive reactions regarding the effectiveness were issued shortly after its introduction by Davidson in 1925. However, the tannic acid method became obsolete after the appearance of several reports on hepatotoxicity in the early forties. Only in present times, with advances in the fields of burn research, does a better understanding of the pathophysiology of the burn syndrome, the involvement of the liver therein, and tannic acid research occur. As a result, with the availability of highly purified tannic acids, the usefulness of tannic acid as an adjuvant therapy has again gained interest. This rise and fall in popularity of tannic acid is also reflected in review articles that have been published over the years on this subject. Lee and Rhoads in 194489 stated that tannic acid was applied successfully and, in fact, had produced a decrease in mortality rate despite the occurrence of liver necrosis. In subsequent reviews, the latter aspect was emphasized.[175,176,177] Conversely, in 1995 Hupkens, et al.,[178] once more made the necessary differentiations in the reports on hepatotoxicity of tannic acid and reevaluated its use for better cosmetic results.

In this respect, a parallel may be drawn between tannic acid and silver, another therapeutic regimen for the local treatment of burns. After a period in which the use of silver was reviled, it has again obtained an important place in the contemporary treatment of burn wounds.[179,180] Similarly, as it appears to be now, highly purified tannic acids might gain interest as a tool to improve wound healing and to reduce scar tissue formation. However, prior to the reintroduction of tannic acid in burn treatment, a thorough benefit-risk analysis should be carried out. This will, in the near future, require controlled prospective studies comparing tannic acid with current standard therapeutic regimens, such as the local application of silver sulfadiazine, with rigorous toxicological assessment in which any detrimental effects of tannic acid on the liver are to be excluded.

In anticipation of such tests, it was attempted in this review to tentatively answer the question of whether or not tannic acid actually is toxic to the liver. From the collected data, it can be concluded that the evidence yet is inconclusive. Thus, many clinical and experimental studies in the past were indicative for a potential hepatotoxic effect of tannic acid. However, tannic acid preparations of ill definition and poor quality were used, often in extremely high concentrations. This could have negatively affected the outcome of these studies. Moreover, liver damage and impairment of liver function also occurred in patients who did not receive tannic acid treatment at all, and these phenomena are now considered part of the burn syndrome. On basis of these considerations, the suggestion by some that tannic acid has been a contributing factor to the death among burn patients seems to be untenable, also in light of the lowered mortality rate found in most clinical studies. It is our opinion that the local application of tannic acid to burn wounds causes no serious hepatic damage, at least not any more than the thermal injury does in itself. A prerequisite is that it is used under strictly controlled conditions, that a highly purified tannic acid product is applied in moderate concentrations (at maximum 2.5- to 5-percent tannic acid), and an adequate pharmaceutical formulation is used, which minimizes decomposition and creates a favorable environment for wound healing.

The library staff of Utrecht University is acknowledged for all their efforts to retrieve relevant articles. This study is financially supported by the foundation Achmea Slachtoffer en Samenleving, Zeist, The Netherlands.

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