Skin, Mucous Membranes and Connective Tissue Healing

Shafer, Beatty and Davis, Proceedings of the Society of Experimental Biology and Medicine (1958),337 found that pretreatment with PHT (25-50 mg/day), for eighteen days prior to making an incision, produced a dramatic increase in tensile strength of healing wounds in rats. See also Refs. 335, 336.

337. Shafer, W. G., Beatty, R. E., and Davis, W. B., Effect of Dilantin sodium on tensile strength of healing wounds, Proc. Soc. Exp. Biol, 98: 348-350, 1958.
335. Shafer, W. G., The effect of Dilantin sodium on liver DNA and restitution, J. Oral Ther. Pharm., 2: 319-323, 1966.
336. Shafer, W. G., Response of radiated human gingival fibroblast-like cells to Dilantin sodium in tissue culture, J. Dent. Res., 44: 671-677, 1965.

Houck, Jacob and Maengwyn-Davies, Journal of Clinical Investigation (1960),172 found that PHT (25 mg/day) decreases dermal water and fat and increases collagen in rat skin. Houck and Jacob 502 showed that PHT diminished the catabolic effect of cortisol which reduces hexosamine, nitrogen and coliagen fractions in the skin of young rats. 

172. Houck, J. C., Jacob, R. A., and Maengwyn-Davies, G. D., The effect of sodium Dilantin administration upon the chemistry of the skin, J. Clin. Invest., 39: 1758-1762, 1960.
502. Houck, J. C. and Jacob, R. A., Connective tissue. VII. Factors inhibiting the dermal chemical response to cortisol. Proc. Soc. Exp. Biol. Med., 113: 692-694, 1963.

Kelln and Gorlin, Dental Progress (1961),189 confirmed the wound healing effects of PHT in rats by showing that two weeks pretreatment with PHT (50 mg/day) increased tensile strength and fibroblast growth compared with controls at seventy two hours after abdominal incision.

189. Kelin, E. E. and Gorlin, R. J., Healing qualities of an epilepsy drug, Dental Prog., 1: 126-129, 1961.

Shafer, Journal of Dental Research (1965),336 found that PHT (5-25 µg/ml) stimulated growth and [3H]-thymidine in corporation of normal human gingival fibroblasts in tissue culture.

336. Shafer, W. G., Response of radiated human gingival fibroblast-like cells to Dilantin sodium in tissue culture, J. Dent. Res., 44: 671-677, 1965.

Kolbert, American Journal of Ophthalmology (1968),504 reported that oral PHT (50 mg/day), for two days preoperatively and twice weekly for two weeks post-operatively, increased the tensile strength of corneal wounds in rabbits.

504. Kolbert, G. S., Oral diphenylhydantoin in corneal wound healing in the rabbit, Amer. J. Ophthal., 66: 736-738, 1968.

Houck, Cheng and Waters, Antiepileptic Drugs (1972),1164 reported that treatment with PHT (100 mg/kg/day, for twelve days) increased the amount of insoluble collagen in the connective tissue of rats. In addition, they observed an increase in another protein (insoluble, noncollagenous) which they termed scleroprotein. With this increase of scleroprotein, there was a significant reduction in the amount of triglyceride or neutral fats. The authors note that these findings in animals are consistent with improved wound healing observed clinically.

1164. Houck, J. C., Cheng, R. F., and Waters, M. D., Diphenylhydantoin, effects on connective tissue and wound repair, Antiepileptic Drugs, 267-273, Woodbury, D. M., Penry, J. K., and Schmidt, R. P., Eds., Raven Press, New York, 1972.

Bazin and Delaunay, Comptes Rendues Academie Sciences (1972),811 demonstrated that in rats treated with PHT for twenty-one days, the collagen content was unchanged in healthy skin, but was increased by 21% in granulomatous tissue. The degree of collagen maturation was increased in both.

811. Bazin, S. and Delaunay,, A., Effect of phenytoin on the maturation of collagen in normal skin and granulomatous tissue, C. R. Acad. Sci. Ser. D., 275: 509-511, 1972.

Eisenberg, Williams, Stevens and Schofield, Journal of International Research Communications (1974),2176 demonstrated that PHT (55 µ M) inhibits the activity of collagenase and collagen peptidase in vitro. The authors noted that PHT's inhibition of collagenase may be related to its effectiveness in treating epiderrnolysis bullosa. See also Refs. 1738,  1817,  2153.

2176. Eisenberg, M., Williams, J.F., Stevens, L. and Schofield, P.J., Mammalian collagenase and peptidase estimation in normal skin and in the skin of patients suffering from epidermolysis bullosa, IRCS, 2: 1732, 1974.

1738. Bauer, E. A., Cooper, T. W., Tucker, D. R. and Esterly, N. B., Phenytoin therapy of recessive dystrophic epidermolysis bullosa: clinical trial and proposed mechanism of action on collagenase, New Eng. J. Med., 303(14): 776-81, 1980.
1817. Eisenberg, M., Stevens, L. H. and Schofield, P. J., Epidermolysis bullosa-new therapeutic approaches, Aust. J. Derm., 19: 1-8, 1978.
2153. Bauer, E.A. and Cooper, T.W., Therapeutic considerations in recessive dystrophic epidermolysis bullosa, Arch. Dermatol., 117:529, 1981.

Kasai and Hachimine, Bulletin of Tokyo Dental College (1974),2647 found that PHT (1-5 µg/ml) stimulated collagen synthesis in all four fibroblast lines tested. The response was greatest in the two lines derived from gingival tissue.

2647. Kasai, S., Hachimine, K., Effect of 5,5-diphenylbydantoin sodium on the synthesis of collagen by some fibroblastic cell lines including gingiva derived cells, Bull. Tokyo Dent. Coll., 15: 53-62, 1974.

Staple and Nakeeb, Journal of Dental Research (1978),2258 demonstrated in rats that, whereas dermal allograft survival was not prolonged, initial union of host and graft epithelium was more rapid in PHT recipients.

2258. Staple, P. H. and Nakeeb, S.J., Effect of diphenylhydantoin (phenytoin) on dermal allograft survival in rats, J. Dent. Res., 57:291, 1978.

Bergenholtz and Hanstrom, Biochemical Pharmacology (1979),2155 demonstrated that PHT (20 µg/ml) increased incorporation of radioactive collagen into cat palatal mucosa grown in organ culture. PHT also decreased collagen degradation.

2155. Bergenholtz, A. and Hanstrom, L., The effect of diphenythydantoin upon the biosynthesis and degradation of collagen in cat palatal mucosa in organ culture, Biochem. Pharmacol., 28:2653-9, 1979.

Hanstrom and Jones, Medical Biology (1979),1882 showed that PHT prevented collagen degradation in cat palatal mucosa during organ culture.

1882. Hanstom, L. and Jones, I. L., The effect of diphenylhydantoin upon degradation of sulphated macromolecules in cat palatal mucosa in vitro, Med. Biol., 57: 177-81, 1979.

Goultschin and Shoshan, Biochimica et Biophysica Acta (1980),1867 demonstrated inhibition of collagen breakdown in gingival tissue obtained from five PHT-treated patients during periodontal surgery and maintained in culture for four days. DNA content of the tissue was also increased compared to controls.

1867. Goultschin, J. and Shoshan, S., Inhibition of collagen breakdown by diphenylhydantoin, Biochim. Biophys. Acta, 631: 188-91, 1980.

Nishikase, Furuya and Takase, IRCS Medical Science (1980),2004 reported that PHT lowered the levels of lipid peroxide, as well as granulation tissue and fluid exudate, in carrageenin-induced inflammation and granulomas in rats. The authors conclude that PHT's inhibition of lipid peroxide accounts for its reduction of granuloma tissue and fluid exudate formation, both manifestations of the inflammatory response.

2004. Nishikaze, O., Furuya, E. and Takase, T., Diphenylhydantoin inhibits the production of lipid peroxide in carrageenin induced inflammation in rats, IRCS Med. Sci., 8: 552, 1980.

Moy, Tan, Holness and Uitto, Clinical Research (1983),2811 studied the effects of PHT (25-50 µg/ml) on the metabolism of collagen in human skin fibroblast cultures. Prolyl hydroxylase and collagenase activity was markedly reduced at these PHT concentrations. PHT did not affect thymidine incorporation or hydroxyproline formation. The authors conclude that PHT affects the post-translational modification of collagen and may reduce its enzymatic degradation, and suggest PHT’s usefulness in patients with increased collagenase activity.

2811. Moy, L. S., Tan, E. M., Holness, R., Uitto, J., Effects of phenytoin on collagen metabolism and growth of skin fibroblasts in culture, Clin. Res., 31(l): 22A, 1983.

Matsuo and Yajima, Japanese Journal of Oral Biology (1985),2773 found that PHT (5-40 µg/ml) stimulated both rat fibroblast proliferation and collagen fibrogenesis in tissue culture.

2773. Matsuo, A., Yajima, T., Cell proliferation and collagen fibrogenesis of cultured fibroblasts, Jpn. J. Oral Biol., 27: 53-63, 1985.

Stress Ulcers

Requena, Forte, Knopf, Scherrer, Kirschner and Levowitz, Surgical Forum (1972),2900 Studied the protective effects of PHT and vitamin A on the formation of stress ulcers in fasted and restrained rats. Both PHT (50 mg, twice daily, subcutaneously) and vitamin A (50,000 units intra-muscularly as a one-time dose) markedly decreased the incidence of stress ulcers compared to controls (p<0.01). When PHT and vitamin A were given together, an even stronger protective effect was noted. PHT also prevented intracellular potassium depletion. The authors suggest that the protective action of PHT stems from its membrane stabilizing properties which, in turn, prevent intracellular potassium depletion and the consequent deleterious effects of the back diffusion of hydrogen ions.

2900. Requena, R., Forte, R., Knopf, M., Scherrer, J., Kirschner, J., Levowitz, B. S., Intracellular potassium and vitamin A in the prevention of stress ulcers. Surg. Forum, 23: 388-9, 1972.

Tasse, The Canadian Journal of Surgery (1982),3005 found that PHT (50 mg, intramuscularly) significantly reduced the formation of stress ulcers in restrained, fasted rats. Vitamin A had no protective effects. The author notes the need for further studies of PHT's effects at lower doses. See also Ref. 3028.

3005. Tasse, D. P., Protective value of diphenylhydantoin and vitamin A against stress ulcer, Can. J. Surg., 25(2): 194-5, 1982.
3028. Tsuchiya, J., Experimental studies on stress ulcer pathogenically related to subarachnoid hemorrhage, Gifu Daigaku Igakubu Kiyo, 29(5): 929-72, 1981.


Frymoyer, Journal of Trauma (1967),1840 demonstrated a statistically significant increased rate of union of fibula fractures in rats treated with PHT (4 mg/kg/day). Clot organization was greater in the treated animals than in controls at fifteen days. At thirty days, the number of fracture unions, quality of callus, amount of compact bone and total fracture score were all greater in the PHT-treated group.

1840. Frymoyer, J. W., Fracture healing in rats treated with diphenylhydantoin (Dilantin), J. Trauma, 16(5): 368-70, 1976.

Sklans, Taylor, Shklar, Journal of Oral Surgery (1967),343 demonstrated that treatment with PHT (40 mg/kg/day), starting either prior to fracture or at the time of fracture, accelerated healing of experimentally produced mandibular fractures in rabbits. Histologically, the PHT-treated animals showed earlier clot organization and increased vascular and connective tissue formation at the site of the healing fracture compared to controls.

343. Sklans, S., Taylor, R. G., and Shklar, G., Effect of diphenylhydantoin sodium on healing of experimentally produced fractures  in rabbit mandibles, J. Oral Surg., 25: 310-319, 1967.

Gudmundson and Lidgren, Acta Orthopaedica Scandinavica (1973),1104 in a controlled study, found that PHT (50 mg/kg/ day) accelerates healing of experimentally-induced tibial fractures in mice. The tensile strength of healing unstable fractures and the breaking strength of healing fractures were significantly greater in the PHT-treated group than in controls. In the PHT-treated animals the fracture callus contained a larger amount of extractable collagen. The authors conclude that a higher rate of collagen synthesis may contribute to the better rate of healing of fractures observed with PHT.

1104. Gudmundson, C. and Lidgren, L., Does diphenylbydantoin accelerate healing of fractures in mice, Acta Orthop. Scand., 44: 640-649, 1973.


Smith and Robinson, Proceedings of the Western Pharmacology Society (1962),505 reported that, in rat, intraperitoneal PHT (10 mg/day), prior to and continuing after hepatectomy, significantly stimulated liver regeneration compared to controls, as measured by both wet and dry liver weights. The PHT-treated animals also showed a much greater fibroblastic reaction around the hepatectomy sites.

505. Smith, D. L. and Robinson, W. A., The effect of diphenylhydantoin sodium on liver restitution in the rat following hepatectomy, Proc. West. Pharmacol. Soc., 5: 9-12, 1962.

Shafer, Journal of Oral Therapeutics and Pharmacology (1966),335 demonstrated, in rats, that PHT (10 mg/day), beginning ten days prior to hepatectomy, stimulated liver regeneration, as measured by wet and dry liver weight. In a second experiment, in mice, they found that PHT increased [3H]-thymidine uptake, indicating a stimulation of nucleic acid synthesis and liver cell proliferation.

335. Shafer, W. G., The effect of Dilantin sodium on liver DNA and restitution, J. Oral Ther. Pharm., 2: 319-323, 1966.

Remmer, 8th International Congress Of Gastroenterology (1968),2248 reported improved liver healing after partial hepatectomy as reflected by increased liver weight and protein in rats treated with PHT (50 mg/ kg/day).

2248. Remmer, H., The acceleration of liver regeneration after hepatectomy by phenobarbital and diphenylhydantoin, Presented at Int. Congress of Gastroenterology, Prague, July 13, 1968.

Khan, Garyounis Medical Journal (1979),2659 studied the effects of PHT (100 mg/kg/day, intraperitoneally, daily for nine days) on liver growth in normal rats and on liver regeneration in partially hepatectomized rats. PHT increased liver weight in both groups compared to controls, with no increase in hepatic water. In addition, PHT stimulated an adhesive reaction around the area of partial hepatectomy which was not seen in controls. The authors conclude that PHT can have a stimulating effect on cells of non-connective tissue origin in both normal and injured livers. However, PHT increases fibroblast proliferation selectively in the injured liver.

2659. Khan, M. T., The effect of diphenylhydantoin on liver regeneration in partially hepatectomized and on liver growth in normal rats, Caryounis Med. J., 2: 49-53, 1979.

Spinal Cord

Gerber, Olson and Harris, Neurosurgery (1980),2195 studied functional recovery after spinal cord injury in animals treated with PHT. Intravenous PHT (20 mg/kg) at time of injury or thirty minutes following injury, and again at six hours, was compared to conventional steroid treatment and no treatment. At two weeks, recovery in the PHT-treated group was significantly greater: three of eleven could run and five could walk, compared to one of five in the steroid-treated group and none in the control group. At six weeks, nine of the eleven PHT-treated animals were running with little motor deficit, compared to two of five in the steroid-treated group and none in the control group. The authors conclude that PHT may offer clinical protection from neurological deficits caused by spinal cord injury.

2195. Gerber, A.M., Olson, W.L. and Harris, J.H., Effect of phenytoin on functional recovery after experimental spinal cord injury in dogs, Neurosurgery, 7(5): 472-6, 1980.


Rovin, Sabes, Eversole and Gordon, Journal of Dental Research (1973),1485 studied the effect of PHT in preventing caries. The authors state that during the course of a previous study on periodontal disease in rats, there had been an unsuccessful attempt to produce gingival hyperplasia with PHT. Although they were unsuccessful in producing gingival hyperplasia, they noticed that the PHT-treated rats did not develop caries. As a result of this observation, the authors conducted a controlled study of the effect of PHT on the prevention of caries in rats. A ligature of the first mandibular molar was used as the irritant for inducing experimental caries. PHT had a marked effect in retarding caries in these animals. The effect was particularly apparent for five months; at the end of ten months, the effect was less. The authors conclude that PHT acted as a caries retarder and that there could be clinical application for their findings. See also Ref. 1724.

1485. Rovin, S., Sabes, W. R., Eversole, L. R., and Gordon, H. A., Dilantin as a caries retarder, J. Dent. Res., 52: 267, 1973.
1724. Apton, R., Dilantin and its relation to caries incidence, Dent. Hyg., 51: 349-51, 1977.

See also Refs. 171, 188, 499, 500, 501, and Clinical--Healing section.

171. Houck, J. C. and Patel, Y. M., Proposed mode of action of corticosteroids on the connective tissue, Nature, 206: 158-160, 1965.
188. Kelin, E. E., Further studies of an epilepsy drug, Dental Prog., 3: 271-273, 1963.
499. Houck, J. C., The.resorption of sodium Dilantin produced dermal collagen, J. Clin. Invest. 41: 179-184, 1962.
500. Houck, 1. C., Dermal chemical response to analogues of Dilantin, J. Invest. Derm., 40: 89-93, 1963.
2107. Vernillo, A. T. and Schwartz, N. B., Collagen and proteoglycan synthesis in 5,5 diphenylhydantoin (Dilantin) treated chondrocytes, J. Cell. Biol., 83(pt. 2): 116a, 1979.