All you need to know about monobenzone（PBP）

Monobenzone (CAS: 103-16-2), also called PBP or monobenzyl ether of hydroquinone (MBEH) is an organic chemical in the phenol family with chemical formula C6H5CH2OC6H4OH. It is used as a topical drug for medical depigmentation. It is a colourless solid that is classified as the monobenzyl ether of hydroquinone. Monobenzone occurs as a white, almost tasteless crystalline powder, soluble in alcohol and practically insoluble in water [1]. Benoquik is one of the product name for monobenzone. Benoquik is Monobenzone 20% Cream and is only allowed and approved product for depigmentation [2]. It is a tyrosinase inhibitor used to treat vitiligo by depigmentation [3].

USES 

Monobenzone is used to treat the uneven appearance of the skin due to a loss of skin color (vitiligo). It works by permanently removing color from normal skin located around skin with vitiligo. This will help to make the appearance of the skin more even. Do not use this drug to treat other skin discoloration problems ("sun spots," "age spots," freckles, skin discoloration caused by hormone medicine, perfumes, pregnancy, or skin trauma). Monobenzone is not a mild cosmetic bleach. Because it causes a permanent discoloration of the skin, it may not be the right treatment for these other skin conditions.

HOW TO USE

This medication is for use on the skin only. Apply a thin layer of the medication to normal-colored skin, usually 2-3 times daily or as directed by your doctor. Avoid getting this product in your eyes or on the inside of your nose or mouth. If you do get this medication in those areas, flush with plenty of water. After using this medication, the skin will be permanently affected and sensitive to sunlight. Avoid prolonged exposure to sunlight, tanning booths, and sunlamps. Always use a sunscreen of SPF 15 or greater, and wear protective clothing when outdoors.It may take up to 4 months before the full benefit of this drug takes effect. Once the desired skin color is achieved, this medication is applied only as needed to maintain your new skin color (usually 2 times a week). Use this medication regularly to get the most benefit from it. To help you remember, use it at the same times each day. Inform your doctor if your condition persists or worsens after 4 months [4].

MECHANISM OF ACTION

Monobenzone is a depigmenting agent whose mechanism of action is not fully understood. It is proposed that it increases the excretion of melanin from the melanocytes. This effect is erratic and may take one to four months to occur while existing melaninis lost with normal sloughing of the stratum corneum. Hyperpigmented skin appears to fade more rapidly than does normal skin, and exposure to sunlight reduces the depigmenting effect of the drug. Following skin depigmentation after topical application of monobenzone, the histological studies indicate similar results as that seen in vitiligo, where the epidermis is intact but with the absence of identifiable melanocytes [5].

SIDE EFFECTS

Mild burning, irritation, redness, cracking, or peeling of the treated skin may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Skin that is not treated with this medication may also become discolored or irregular in appearance. Sometimes these effects may be permanent. Ask your doctor or pharmacist for more details. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS

Before using monobenzone, tell your doctor or pharmacist if you are allergic to it; or to hydroquinone; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: other skin conditions. During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor. It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding [4].

References

[1] https://www.drugbank.ca/drugs/DB00600
[2] Wikipedia: monobenzone
[3] https://medkoo.com/products/10897
[4] https://www.medicinenet.com/monobenzone-topical/article.htm
[5] https://pubchem.ncbi.nlm.nih.gov/compound/Monobenzone#section=Mechanism-of-Action