The Effects of Nitrofurazone on Wound Healing in Thoracoabdominal Full-Thickness Skin Defects

Sami Karapolat, MD; Banu Karapolat, MD; Alaaddin Buran, MD; Burcu Kemal Okatan, MD; AtilaTurkyilmaz, MD; Turan Set, MD; CelalTekinbas, MD

Disclosures

Wounds. 2020;32(5):134-141. 

In This Article

Discussion

This experimental study on the use of nitrofurazone in full-thickness skin defects underlines 6 points. First, nitrofurazone caused a marked decrease in inflammatory cell concentration in the defected region. Collagen accumulation significantly increased in the defected region in the group in which nitrofurazone was used. Nitrofurazone caused extensive granulation tissue formation within the first week, but the granulation tissue disappeared almost completely in the specimens at the end of the experiment. Nitrofurazone caused significant increases in reepithelization in the defected region. With the use of nitrofurazone, the skin defect area formed at the beginning showed minimal superficial tissue loss at the end of the experiment and disappeared almost completely. The healing rate values were distinctly higher in the rats in the nitrofurazone group compared with the control group.

Skin integrity impairing with defects that occur after an operation or biopsy — due to a trauma or burn or those that occur in patients who have been bedridden for a long time (eg, pressure injuries) — are the defects frequently encountered in many surgical clinics.[7] As a barrier against external factors, the skin is the most important organ in terms of general functioning.[4,8] After a wound occurs, the recovery involves a process starting with hemostasis and inflammation and continuing with cell proliferation and remodeling/scar formation.[1,4] Inflammation is an important phase in wound healing, and the number of inflammatory cells and particularly that of neutrophils increase in the defected area during the early days of the recovery process.[1,7] However, the number of these inflammatory cells should decrease during the following periods, as a strong inflammatory response increases tissue damage, delays epithelialization and collagen synthesis, and plays an important role in prolonging healing by slowing it down.[13] In the present study, the strong inflammatory response that occurred at day 3 in the defected regions of the control group retained the same severity until day 10. The reason for the strong inflammatory response to stay at the same severity throughout the experiment could have been due to the major effects of the inflammation phase, which is the first stage of the normal wound healing process.

In the group in which nitrofurazone was used, however, a gradual decrease occurred in the number of inflammatory cells during the experiment, and the scores dropped to the lowest level at day 10 when the experiment was terminated. Occurrence of severe inflammation in the defected region at an early stage is an expected situation, but a decrease occurs in this inflammation during the healing process.[1,13] Nitrofurazone facilitated and accelerated this physiological decrease in inflammation, which enabled acceleration in wound healing and defect closure. It is believed the nitrofurazone had a bactericidal effect due to its antimicrobial activity against many microorganisms (primarily streptococci) that exist in the normal skin flora of the rats, but could become pathogenic due to the defect, and this process reduced the inflammatory response.[5,6]

The main function of the fibroblasts concentrated in the tissue at the proliferation phase of wound healing is the collagen synthesis that begins at day 2 of injury and shows the highest activity at day 7.[14] This new collagen tissue formation in the defected area enables newly developing cells to bind to each other with stronger bonds, facilitates closure of wound edges, contributes to contraction, and makes the new tissue stronger and firmer.[1,15] Nitrofurazone increased the collagen formation in the tissue throughout the experiment, which had a positive impact on the wound healing process. However, collagen normally decreases at the remodeling stage due to its increased collagenase activity, and its shape turns into collagen networks with small fibrils.[1] Since the present study ended after day 10, the effects of nitrofurazone that would be used for a longer time on collagen production remained unknown.

Generally, the amount of granulation in the tissue increases from day 5 in the wound healing process, but when healing is completed and reepithelization becomes predominant, the granulation tissue is observed to disappear.[1,13] In this study, nitrofurazone caused formation of a dense granulation tissue in the defected region within 7 days; interestingly, the granulation tissue disappeared almost completely in the specimens at day 10 when the experiment ended. Known as the last suitable point for detecting wound healing, reepithelization was seen in low amounts in group B in the first week and showed a considerable increase between days 7 and 10. These 2 histopathological parameters manifested in group A with dense granulation tissue and partially increased reepithelization This result shows there was no healing in these periods in the wound that was left on its own, but wound healing accelerated with the use of nitrofurazone. In addition, the absence of granulation tissue and highest level of reepithelization in the nitrofurazone group at day 10 meant wound healing was almost complete. The absence of granulation tissue and highest level of reepithelization indicated that the once daily application of nitrofurazone provided the maximum benefit at day 10 of the present study.

Widespread skin defects often occur at the beginning of the wound formation process due to medical issues, including vascular problems, feeding difficulties, and infections.[3,16] During wound healing, certain factors, such as infection control and angiogenesis, enable the aforementioned skin defects to disappear. In the present study, a skin defect area was seen in the control group from the beginning of the study, but the skin defect areas gradually decreased in group B; minimal defects were found in the tissue at day 10 for group B. No superficial tissue loss should be present in the tissue, and extensive fibrosis should be seen at the stage of completion of wound healing. The current findings may indicate that nitrofurazone could be used to prevent the formation of superficial tissue loss from being infected by local or external microorganisms; the present study found nitrofurazone accelerated the wound healing process.

The similar healing rate values observed in groups A and B during the first 3 days of this study suggest nitrofurazone does not have any effect on wound healing during the first few days. However, the healing rate was noticeably higher at days 7 and 10 in the nitrofurazone group than in the control group. At day 10, the healing rate in group B reached 80%. With an approximated 20% difference between the nitrofurazone group and control group, the results in the present study could be interpreted as a macroscopic indication that nitrofurazone potentially accelerates wound healing.

In the wound healing process, neutrophils, macrophages and endothelial cells, and fibroblasts generate a number of reactive oxygen products.[16] Similarly, free oxygen radicals cause formation of reactive oxygen products and lipid peroxidation.[17] As a result, the wound healing process is negatively affected due to decreased protein synthesis, elevated leukocyte infiltration, impaired extracellular matrix formation, and prolonged inflammatory response.[17,18] The major antioxidant enzymes that fight with this situation are glutathione peroxidase and superoxide dismutase. Glutathione peroxidase not only prevents initiation of lipid peroxidation but also enables metabolization of hydroperoxides that emerge as a result of lipid peroxidation. A decrease in the activity of this enzyme leads to hydrogen peroxide accumulation and cell damage. Superoxide dismutase exists in all aerobic cells. This enzyme is present in cytosol and mitochondria and protects cells from the harmful effects of superoxide radicals by deactivating them. In a study conducted by Hong et al,[19] depending on the dose, nitrofurazone was found to increase these antioxidant enzymes in protozoan Euplotes vannus cells. Further animal studies showing in vivo that similar effects of nitrofurazone can occur in the cells of wounds would increase the value of the positive results obtained in the present study. The authors believe these results will lead to future human studies.

Nitrofurazone is a derivative of nitrofuran and has a broad spectrum, including Gram-positive and Gram-negative bacteria (eg, Staphylococcus aureus, Streptococcus, Escherichia coli, Clostridium perfringens, Aerobacter aerogenes, Proteus spp). Nitrofurazone has a bactericidal effect on most of these microorganisms that cause surface infections.[9] The mechanism of action of nitrofurazone is the inactivation of ribosomal proteins and other macromolecules, with consequent inhibition of proteins, DNA, RNA, and cell wall synthesis, blocking the aerobic metabolism of bacterial cells and inhibiting the carbohydrate metabolism enzymes of bacteria.[10] It can be used as an adjuvant in the healing process of cutaneous wounds, since along with the antimicrobial activity, it interferes in the formation of granulation tissue.[10] The microorganisms colonized on wounded tissue are killed and digested by the phagolysosomes of leukocytes.[20] In the meantime, reactive superoxide and hydroxyl radicals are formed as a result of oxidative reactions.[18,20] Although these actions take place in a time as short as milliseconds, they are toxic if uncontrolled.[21] Owing to its antibacterial property, topically applied nitrofurazone reduces the number of bacteria in the wound site and protects the tissue from toxic effects that would occur through the aforementioned mechanism.[5,6]

In a study on white domestic pigs, nitrofurazone was found to delay wound healing.[8] However, that study[8] was conducted about 40 years ago and only evaluated the reepithelialization rates. The result of the study[8] can be contributed to the fact that the study was not a large-scale histopathological study in which the entire phases of the wound healing process were evaluated by investigating various parameters involved in it. In a study included in the literature, Ozkaya et al[5] formed partial-thickness wounds on the backs of rats and applied topical nitrofurazone, rifampicin, nitrofurazone-rifampicin, and bacitracin-neomycin. The authors found nitrofurazone did not delay wound healing, but the wound surface was larger during the healing process as compared with the other agents.[5] No histopathological examination was performed in that study;[5] the wound healing times and sizes were explored through observation and macroscopic examination. The results of the current study, in conjunction with the histopathological data collected herein, support the positive effects of nitrofurazone obtained in the study by Ozkaya et al.[5]

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