Metformin - For the dermatologist

Abstract

Metformin though primarily an antidiabetic drug, has found to play an important role in a number of cutaneous disorders. Because of its role in improving hyperinsulinemia, it has proven beneficial in hormonal acne, hidradenitis suppurativa (HS) and acanthosis nigricans. Its antiandrogenic properties further serve as an add-on to the conventional management of hirsutism associated with polycystic ovarian syndrome. Very recently, systemic usage of metformin for psoriasis and cutaneous malignancies has shown promising results. Interestingly, metformin has also been topically used in hyperpigmentary disorders with pertinent levels of improvement and happens to be the most recent addition to the list of dermatologic indications. Though an oral hypoglycemic agent to begin with, metformin today has proven to be a boon for dermatologists.

Keywords: Hyperandrogenism; hyperinsulinemia; hyperpigmentary disorders; metformin; skin cancer.

Figure 1

Mechanism demonstrating the antagonizing role of metformin in acanthosis nigricans

Figure 2

(a) Status of axillary acanthosis nigricans prior to starting therapy (b) Status of axillary acanthosis nigricans after the institution of combination therapy with metformin and tapering isotretinoin after 3 months. Considerable improvement can be visualized here. [Figure adapted from Walling HW et al. Improvement of acanthosis nigricans on isotretinoin and metformin. JDD 2003;2:677-81]

Figure 3

(a) Status of nuchal acanthosis nigricans prior to initiation of therapy. (b) Status of nuchal acanthosis nigricans after starting treatment with metformin and tapering isotretinoin after 3 months. Considerable improvement can be visualized here. [Figure adapted from Walling HW et al. Improvement of acanthosis nigricans on isotretinoin and metformin. JDD 2003;2:677-81]

Figure 4

Mechanism of metformin in acne

Figure 5

Mechanism of metformin in hyperpigmentary disorders

Figure 6

(a) Eruptive xanthomas of the right upper limb prior to treatment (b) close-up view of the same lesions prior to treatment (c) resolution of eruptive xanthomas with post inflammatory hyperpigmentation after 6 months of treatment with metformin and bezafibrate (d) close up view of the same lesions after therapy. [Figure adapted from Striet E, Helmbold P. 65 year old man with yellow orange papules on both forearms eruptive xanthomas. Hautarzt 2009;60:834-7]

Figure 7

(a) Status of axillary hidradenitis suppurativa prior to starting therapy with metformin (b) status of axillary hidradenitis suppurativa 24 weeks after initiation of metformin therapy. To note here is that this patient had been recalcitrant to treatment with other antibiotics and after therapy with metformin noticed marked improvement. [Figure adapted from Verdolini et al. Metformin in the treatment of hidradenitis suppurativa: a little help along the way. JEADV 2013;27:1101-8]

Figure 8

(a) Hidradenitis suppurativa of the groins and the abdominal area prior to treatment with metformin (b) similar patient 12 weeks after initiation of metformin therapy with considerable improvement. [Figure adapted from Verdolini et al. Metformin in the treatment of hidradenitis suppurativa: a little help along the way. JEADV 2013;27:1101-8]

Figure 9

(a) Status of axillary hidradenitis suppurativa prior to starting therapy with metformin (b) Status of axillary hidradenitis suppurativa 4 months after commencement of treatment with metformin. To note here is the marked improvement in sinus tracts and leaking abscesses. [Figure adapted from Arun B, Loffeld A. Long standing hidradenitis suppurativa treated effectively with metformin. CED 2009;34:920-1]