Monobenzone Research Articles

Commentary on The Maximization Test

Origins John Draize of the FDA published a procedure for identifying contact allergens, using human volunteers. It became known as the ‘‘repeated insult test’’ and was supposed to be an improvement on the Schwartz-Peck test, also under FDA sponsorship. Though Draize’s method did not have the force of law, it came to be regarded as a quasi-legal regulation which put a manufacturer of a topical drug at risk if the repeated insult test had not been done. To Dr. Kligman’s astonishment, he could not find any published data which validated Draize’s test. He questioned the number of subjects and exposures. Why 200 subjects? Perhaps 100 would suffice? Why ten exposures, instead of 5, or 15 or 100? Subsequently, he learned there was a file in the FDA archives, which on the basis of unpublished experience with many topical agents, justified Draize’s specifications. Dr. Kligman reasoned that the Draize test was ‘‘based not on experimentation but on revelations originating in outer space.’’ Clinical experience had demonstrated that creams containing penicillin were strongly allergenic, forcing them off the market. Also, topical neomycin was known to have an appreciable risk of sensitization. Certain topical bleaching agents, notably monobenzyl ether of hydroquinone, which were effective only when applied daily for many months, could not continue to be used because a substantial percentage of patients became sensitized. The stage was set for the important, and impertinent, question. Would these well-known allergens be detected by the Draize repeated insult test on 200 subjects? Dr. Kligman had available a large population of prisoner volunteers on whom the Draize test could be tested for its validity. The result was stunningly negative. This ‘‘exalted, exaggerated, formidable procedure was incapable of recognizing sensitizers.’’ It almost guaranteed that a formulation would pass with flying colors. In a ‘‘kinky’’ sort of way, this lack of sensitivity may actually have increased the reputation and commercial usefulness of the test. After all, positive results hang a cloud of allergenicity over a product which might be otherwise quite useful. Benzoyl peroxide is an example of a useful drug which is potentially a strong allergen. On the other hand, failure to detect allergenic substances that are used daily can have disastrous effects. For instance, the manufacturers of tetrachlorosalicylanilide claim to have done three separate 200-subject Draize tests in different facilities without discovering that this bacteriostat, incorporated in soaps, was a potent allergen. Had that been known, the calamitous epidemic of photoallergy could have been averted.

Rapid Induction of Thy-1 Antigenic Markers on Keratinocytes and Epidermal Immune Cells in the Skin of Mice Following Topical Treatment With Common Preservatives Used in Topical Medications and in Foods

Earlier experiments from our laboratory revealed that the medication most commonly used for depigmenting patients with vitiligo, monobenzyl ether of hydroquinone (MBEH), when applied to the skin of DBA/2 mice caused an increase in the population density (cells/mm2) of identifiable Ia+ and ATPase+ Langerhans cells. Further, this increase in Langerhans cell density could be correlated with an increase of contact hypersensitivity (CHS) reactivity to dinitrofluorobenzene (DNFB). The current experiments demonstrated that other compounds chemically similar to MBEH, such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), which are used as preservatives/antioxidants in many topical medications, cosmetics, food, and rubber products, can in five days significantly increase the population density of Thy-1+ dendritic epidermal cells. These compounds had no effects on Ia+ cells. This observation suggests that the Thy-1+ DEC cells may be more mobile and/or their surface markers may be readily expressed and are not a slowly mobile (trafficking) population of cells as suggested by the results of previous work. In addition, these parasubstituted phenolic compounds behaved like pertussis toxin and induced Thy-1 and Ia expression on keratinocytes. These changes in Thy-1 immune markers were not accompanied by functional alterations in the immune response to contact allergens as measured by the ear swelling technique.

Usefulness of retinoic acid in the treatment of melasma

Melasma is a circumscribed brown macular hypermelanosis of the areas of the face and neck that are exposed to light. Clinical trials with various depigmenting formulations containing hydroquinone were conducted to determine the ideal concentration of hydroquinone, retinoic acid, and corticosteroids for the treatment of melasma. The compounds were tested with and without the concomitant use of topical sunscreen preparations. Based on the results of the trials and our earlier clinical experience, we conclude that treatment of melasma should involve the following: avoidance of sun exposure, constant use of broad-spectrum sunscreens, and topical application of a cream or lotion containing 2% hydroquinone and 0.05% to 0.1% retinoic acid (tretinoin). Patients should suspend use of oral contraceptives and other agents that promote skin pigmentation. The monobenzyl ether of hydroquinone should never be used in melasma therapy.

Modulation of the population density of identifiable epidermal Langerhans cells associated with enhancement or suppression of cutaneous immune reactivity.

The epidermis on the backs or ears of DBA/2 mice treated for 7 days with a 20% concentration of monobenzyl ether of hydroquinone (MBEH) had a significantly greater population density of ATPase- and Ia-positive cells compared with control mice treated with diluent. There was no decrease or increase in ATPase- or Ia-positive cells at sites distal from the treated tissue. This increase in population density of Langerhans cells was associated with a significant increase in functional afferent immune reactivity measured by allergic contact hypersensitivity. We also found evidence for enhanced efferent immune reactivity. Animals treated on the ears for 7 days with MBEH were sensitized to DNFB on untreated back. MBEH treated ears with more Ia-positive Langerhans cells demonstrated a threefold greater increase in swelling after the DNFB challenge than the control mice. Results of other studies suggest that the afferent and efferent enhanced immune reactivity produced by MBEH are local effects. We postulated that MBEH produced its effects by activating the oxidation of arachidonic acid (AA) to prostaglandins. To test this, we applied AA to mouse skin. AA has a biphasic effect on epidermal Langerhans cells: in low doses it increases their number; in high amounts it decreases the number of identifiable cells with either the Ia or the ATPase technique. An increased population density of identifiable epidermal Langerhans cells induced with AA was correlated with an increase in afferent and efferent immune reactivity. In contrast, reduction of Langerhans cells with larger amounts of AA suppress the afferent and efferent limb of the immune response. DNFB applied to skin with decreased Langerhans cell density from AA induced a state that mimics immune tolerance. The findings are significant because we report the only method to either increase or decrease the population density of Langerhans cells: and to modulate up or down the afferent or efferent limbs of the cutaneous immune response. Our results also suggest that the Langerhans cell may be involved in the efferent limb of the immune efferent response. These effects may be modulated in part by products of AA metabolism.

An Evaluation of the Effectiveness of Azelaic Acid As a Depigmenting and Chemotherapeutic Agent

In the past five years, it has been reported that certain dicarboxylic acids (C8-C13) and azelaic acid (C9) (AZA), in particular, have a remarkable effect in the management of lentigo maligna, human malignant melanoma, and certain disorders of hyperpigmentation. Preclinical trials, therefore, were undertaken in order to evaluate the effectiveness of AZA as a depigmenting agent and as a chemotherapeutic agent. Twenty-seven uniformly black pigmented guinea pigs were given topical applications of various concentrations (3, 5, 10, 15, and 20%) of AZA preparations for 8 weeks, and their effects on the melanocytes of epilated skin of the backs and the nonepilated ears of guinea pigs were compared to the effects of well-known depigmenting agents. Whereas 4-isopropylcatechol, monobenzylether of hydroquinone, monoethylether of hydroquinone, hydroquinone, and 4-hydroxyanisole were found to be selectively cytotoxic to melanocytes in black-skinned guinea pigs, AZA has little or no visually recognizable effect on melanocytes in these animals. The therapeutic effect of local s.c. injections of various concentrations of AZA preparations on the development of s.c. implanted B-16 melanoma tumor was evaluated in 96 C57BL/6J mice. In addition, 31 BDF1 mice, implanted i.p. with B-16 melanoma tumor, were used to assess the effect of 100-500 mg/kg concentrations of AZA administered i.p. In both studies, AZA revealed no significant tumoristatic or tumoricidal effect on the size, color, and growth of melanoma. The effect of AZA was also evaluated on S-91A (melanotic or pigmented) and S-91B (amelanotic) human melanoma cells in culture. Low concentrations (10(-5) and 10(-3) M) of AZA had no inhibitory effect on the growth of these cells. Only at higher concentrations (greater than 10(-3) M) was a cytotoxic effect on cell viability observed. These observations indicate AZA is not selectively cytotoxic to normal and proliferative melanocytes and has no apparent inhibitory effect on the formative process of melanin pigmentation.

Corneal and conjunctival effects of monobenzone in patients with vitiligo.

Monobenzone (the monobenzyl ether of hydroquinone [Benoquin]) is used topically by patients with extensive vitiligo to depigment their remaining normally pigmented skin. A patient who had been applying the drug for one year had an anterior linear deposition of pigment in both corneas. Of 15 additional patients with vitiligo, 11 of whom were using monobenzone, acquired conjunctival melanosis in two patients and pingueculae in three may have been related to monobenzone use. Light and electron microscopy of one corneal epithelial scraping and 12 conjunctival biopsy specimens revealed pleomorphic, single-membrane-limited intracytoplasmic inclusions within the corneal epithelium and within the epithelium, fibrocytes, histiocytes, and vascular endothelium of the conjunctiva. The ultrastructural aspects of these inclusions suggested that they are residual bodies containing lipid and lipofuscin.

Monobenzylether of hydroquinone. A retrospective study of treatment of 18 vitiligo patients and a review of the literature.

Of 18 severely afffected vitiligo patients who used 20% monobenzylether of hydroquinone (MBEH, Benoquin) as a depigmenting agent, 8 achieved complete depigmentation after 10 months or more of use and 3 dramatic but no complete hypopigmentation. The 3 patients with no results did not use MBEH for more than 4 months. Complications were frequent particularly among those who did well, but only 1 case of contact dermatitis limited therapy. All patients who depigmented fully were very pleased with their results. As depigmentation induced by MBEH is generally irreversible, MBEH use must be reserved for induction of complete depigmentation of severely affected vitiligo patients who cannot or do not choose to repigment and who can accept the permanence of never tanning. The history, histology and mechanism of MBEH depigmentation are discussed.

MONOBENZYLETHER OF HYDROQUINONE. ITS EFFECTS ON THE ACTIVITY OF EPIDERMAL MELANOCYTES.

The effect of the application of monobenzylether of hydroquinone on the melanocytes in the skin has been studied in pure black and pure red male guinea pigs. Melanogenesis was greatly inhibited in most animals. The size of the melanocytes became reduced, and the melanin present within and outside the melanocytes was diminished. Four weeks after the cessation of treatment the effect of the drug was seen to be wearing off. The vertical skin sections showed a great increase in the thickness of the epidermis and evidence of dermatitis. The melanocyte counts revealed a reduction in number in the majority of the black animals and a rise in number in the red animals. A statistical analysis of the counts, however, showed that they were not significantly altered.

Leukoderma Following Monobenzyl Ether of Hydroquinone Bleaching

Treatment of vitiligo in the Negro with monobenzyl ether of hydroquinone (MBH) producing complete and uniform depigmentation of the normal uninvolved Negro skin has recently been reported.1It is not the purpose of this report to discount such results but rather to emphasize the unpredicability of bleaching with MBH when it is used on normal Negro skin or for pathologically pigmented white skin.2-5No Negro subject in the present study had vitiligo although one did have a long standing leukoderma from previous exposure to rubber gloves containing agerite alba, the antioxidant from which MBH was originally derived. His response to treatment with MBH was similar to the others where depigmentation was achieved. Comparable results were also observed when MBH was used on pathologically pigmented white skin. Methods and Results in Negro As part of a clinical study to determine the effectiveness of monobenzyl ether of hydroquinone (MBH) as

Hydroquinone Bleaching

Introduction Lightening pigmented blemishes with a bleaching agent has never been very satisfactory. This study was undertaken in an effort to develop a safe and effective bleaching cream. The unpredictability of bleaching coupled with the frequently alarming progression of the bleaching effect of monobenzylether of hydroquinone (MBH), even after applications have been discontinued, is now well established.^1,2Even in much lower concentrations of MBH than is generally recommended, leukomelanoderma has been observed with significant frequency.³The complete loss of pigmentation in a therapeutically induced leukoderma after the use of MBH is especially traumatic to the patient, as well as being most disconcerting to the physician. The correction of these leukodermatous changes has proven to be particularly stubborn. 8-Methoxypsoralen (8-MOP) has been disappointing in its effectiveness as a treatment.⁴ <h3>Methods</h3> This report is based on the results of a 21/2-year study of hydroquinone and 2 of its derivatives

Dermatitic and Pigmentary Reactions to Monobenzyl Ether of Hydroquinone

Dermatitic and Pigmentary Reactions to Monobenzyl Ether of Hydroquinone

Leukomelanoderma Subsequent to the Application of Monobenzyl Ether of Hydroquinone

The role of monobenzyl ether of hydroquinone as a cause of depigmentation has been known since the report of Oliver, Schwartz, and Warren 1 in 1940. These authors studied 20 patients with a peculiar leukoderma localized to the hands and forearms, produced by a type of rubber gloves in which Agerite Alba had been used as an antioxidant. The leukoderma occurs primarily on the areas in direct contact with the causative agent but was also observed affecting the trunk and extremities. One of their patients was a Negro with a striking depigmentation of the abdomen, upper part of the thighs, and buttocks. The authors stated that this could not be explained except that it was probably due to rubbing sweat and water off his body. Sulzberger 2 mentioned a Negro with a generalized vitiligoid depigmentation, almost resembling an albino. The discovery of the properties of mono

Quantitative determination of antioxidants, after chromatographic separation on completely acetylated filter paper. III. Determination of 1. ρ‐(ρ′‐tolylsulphonylamino)phenyl‐ρ‐toluidine; 2. di‐o‐tolylethylenediamine; 3. hydroquinone monobenzyl ether

AbstractMethods are described in this paper for the quantitative determination of three antioxidants in vulcanised rubber. The antioxidants are extracted from the rubber compound, separated by partition chromatography on completely acetylated filter paper and determined colorimetrically by appropriate colour reactions.ρ‐(ρ′‐Tolylsulphonylamino)phenyl‐ρ‐toluidine is oxidised by means of a substituted benzoylperoxide. Both the other antioxidants are coupled with diazotized sulphanilic acid.

The physiology of pigmentation

1. 1. The mature pigment-producing cell, the melanocyte, is derived from a short-lived embryonic structure, the neural crest. 2. 2. Valuable information on the inheritance of pigmentation has been derived from mice, fowl, fishes, and the fruit fly, Drosophila. A given gene affects a given aspect of the pigmentation process. 3. 3. Melanin is formed by the oxidation of tyrosine to 3,4-dihydroxyphenylalanine (dopa). Tyrosinase, a copper protein enzyme, acts as a catalyst in this reaction. Molecular oxygen must be present for this reaction to take place. Lack of any one of these substances prevents melanin formation. 4. 4. Advances in knowledge of the physiology and biochemistry of this basic reaction and the chemical and physical factors influencing it have made possible newer therapeutic methods of inhibiting or accelerating pigmentation. 5. 5. The most effective drug for producing pigmentation is 8-methoxy-psoralen, and for depigmentation is monobenzylether of hydroquinone.

DEPIGMENTATION FROM ADHESIVE TAPE

To the Editor: —Blank and Miller, in their excellent article on rubber adhesives in shoes as the cause of dermatitis of the feet ( J. A. M. A. 149 :1371 [Aug. 9] 1952) state that they did not observe depigmentation action of the monobenzyl ether of hydroquinone but only the sensitizing property. The photographs below are representative of several patients seen here in the last two years with what we call tape vitiligo, i. e., depigmentation presumably due to the monobenzyl ether of hydroquinone used as an antioxidant in the rubber of ordinary surgical tape. All the patients of this type we have seen have been Negroes. Although their main depigmentation has been due to adhesive tape, both patients in these photographs show depigmentation of the feet in a pattern conforming to that of the rubber-containing shoes they wore. The patients we have observed have described no or very little

Negative effects of oral monobenzyl ether of hydroquinone in malignant melanoma in man.

Daily oral doses of 0.3 to 27 g of monobenzyl ether of hydroquinone, for total doses of 2.9 to 1490 g in 21 to 214 days, had no effect upon the growth of malignant melanoma in 8 patients. Ingestion of mono-benzyl ether of hydroquinone produced no toxic effects other than transient nausea and vomiting when the daily dose exceeded 10 g.

Occupational leucoderma from rubber dust and debris.

OLIVER, Schwartz, and Warren¹were the first to report their observation that leucoderma may occur as a result of occupation. In their patients areas of depigmentation developed after contact with rubber containing the antioxidant monobenzyl ether of hydroquinone. Since then, W. D. McNally²presented a number of similar cases of depigmentation in Negro workers. Peck and Sobotka³discussed in great detail the experimental and physiochemical aspects of this pigmentary disturbance. Spencer⁴later recorded additional cases of leucoderma due to "agarite alba," the trade name of the antioxidant monobenzyl ether of hydroquinone. Recently we have encountered nine cases of leucoderma in white workers who came in contact with dust and debris containing "agarite alba." These workers are machine operators who sew thin rubber strips onto asbestos pads. In the course of this operation a heavy alkaline oily dust is created, which settles down upon the face, hands,

Effect of hydroquinone monobenzyl ether on melanin formation in vitro.

It has been shown that ethyl carbamate, which inhibits the tyrosine – tyrosinase reaction, accelerates the autoxidation of 3,4-dihydroxyphenylalanine to melanin1. Other substances known to inhibit the tyrosine – tyrosinase reaction have been investigated for this accelerating effect. One such substance is hydroquinone mono-benzyl ether2,3. The inhibition of the tyrosine – tyrosinase reaction by hydroquinone mono-benzyl ether was confirmed, but no evidence of any accelerating effect on the autoxidation of 3,4-dihydroxyphenylalanine was obtained; in fact, there was a small but definite degree of inhibition of this reaction.

PIGMENTARY DISTURBANCE FOLLOWING EXPOSURE TO MONOBENZYL ETHER OF HYDROQUINONE

In 1940, Schwartz, Oliver and Warren1reported the presence of depigmentation secondary to the wearing of yellow rubber gloves. The etiologic factor responsible for the leukoderma was traced to monobenzyl ether of hydroquinone (agerite alba®), an antioxidant used in the preparation of the rubber. After the original report, Schwartz,2in 1947, recorded several additional cases. The purpose of this communication is to report further instances of this cosmetic disorder, including new data, to record the first case known to us in which hyperpigmentation resulted, to emphasize the probability that this dermatosis is more frequently encountered than the literature implies and to stress the fact that this disorder is not solely occupational in origin. Considering the diversified and numerous rubber products previously treated with monobenzyl ether of hydroquinone, the determination of the origin of this pigmentary disorder often might prove difficult or impossible. The reports in this paper include

LEUKODERMA PRODUCED BY ANTIOXIDANTS

THE PURPOSE of this paper is to present additional cases of leukoderma produced by antioxidizing agents contained in manufactured articles. The chemistry of rubber and rubberized industries has developed not only along lines of greater production of synthetic products but also toward extending the aging of these goods. For this latter objective, the chemical compound "agarite alba," the trade name for monobenzyl ether of hydroquinone, an antioxidant of pigment, is usually added. This observation was first established by Oliver, Schwartz and Warren.¹These authors observed in the tanning industry occupational leukoderma in men wearing rubber gloves which contained this antioxidant to help the aging of rubber. Another observation was made of occupational leukoderma in a woman employed to wash contraceptive diaphragms in a gynecologic laboratory.² <h3>REPORT OF CASES</h3><h3>Case 1.—</h3> E. B., a man aged 29, consulted me because of the appearance of white patches on the hands.