TABLE 1.
Baseline characteristics from included trials with metformin for melasma.
| Characteristics | No. (%) a | ||
|---|---|---|---|
| Ali Mapar and Namdari, (2019): n = 60 | Banavase Channakeshavaiah and Andanooru Chandrappa (2020): n = 40 | AboAlsoud et al (2022): n = 40 | |
| Participant characteristics | |||
| Mean age in year ± SD; range (min–max) | 35.2 ± 7.1; not reported | 37.3 ± 8.3; 23–84 | >18 (not specified) |
| Female | 60 (100.0) | 33 (82.5) | Not reported |
| Mean duration of melasma in year ± SD; range (min–max) | Not reported | 2.7 ± 2.7; 0.1–9.0 | 2.3 ± 1.6; 0.5–6.0 |
| Severity of melasma: mean MASI score ± SD; range (min–max) | 11.2 ± 4.0; 4.8–24.6 | 7.1 ± 5.4; not reported | 14.2 ± 9.0; 1.2–31.7 |
| Family history of melasma | Not reported | 17 (42.5) | 8 (20.0) |
| Site of melasma | |||
| Malar | Not reported | Not reported | 39 (97.5) |
| Forehead | Not reported | Not reported | 10 (25.0) |
| Moustache | Not reported | Not reported | 7 (17.5) |
| Trial characteristics | |||
| Country of enrollment | Iran | India | Egypt |
| Study setting and design | Monocentric, parallel-group | Monocentric, parallel-group | Monocentric, parallel-group |
| Trial registry | Not reported | CTRI/2018/12/016588 | Not reported |
| Randomization method | Simple random sampling | Simple random sampling | Simple random sampling |
| Trial blinding | Double-blind (not specified) | Open-label | Open-label |
| Inclusion criteria | • Female participants who were not on topical treatment for melasma in the last 3 months | • Adult participants who were not on any medications for melasma for at least 2 weeks for topical therapy, 1 month for systemic steroids, or 3 months for cosmetic procedures (i.e., laser ablation, dermabrasion, or peels) | • Adult participants who were not on any medications for melasma for at least 1 month for topical or systemic treatments, or 3 months for cosmetic procedures (i.e., laser ablation, dermabrasion, or peels) |
| Exclusion criteria | • Male gender | • Pregnant and lactating women | • Pregnant and lactating women |
| • Pregnant and lactating women | • Receiving oral contraceptive pills or phenytoin | • Receiving oral contraceptive pills | |
| • Receiving oral contraceptive pills or photosensitivity drugs (tetracycline, spironolactone, phenytoin, and carbamazepine) | • Had history of renal dysfunction, acne vulgaris, or rosacea | • Had history of renal or liver dysfunction, active acne vulgaris, or rosacea | |
| • Had history of renal dysfunction (glomerular filtration rate less than 30 mL/min/1.73 m2) | • Allergic to the medications trial | • Allergic to the medications trial | |
| • Atrophy and telangiectasia in the site of melasma | |||
| • History of drug allergy | |||
| Treatment group | Metformin 15% cream (aqueous phase of metformin powder 15% and oil phase) apply twice daily | Metformin 30% lotion (mixing 30 g of metformin powder [Systopic laboratories pvt.ltd] with 70% alcohol and propylene glycol in 30% weight: volume ratio) apply at night time daily | Metformin 30% cream (crushing metformin 500 mg tablets [Mina Pharm, ARE] with 70% alcohol and propylene glycol in 30% weight: volume ratio) apply at night time daily |
| Comparison group | Placebo-controlled (not specified) | Active-controlled: triple combination cream (Kligman’s formula; hydroquinone 2% + tretinoin 0.025% + fluocinolone acetonide 0.01%) apply at night time | Active-controlled: triple combination cream (Kligman’s formula; hydroquinone 2% + tretinoin 0.025% + fluocinolone acetonide 0.01%) apply at night time |
| Co-intervention | Sunscreen of SPF 50 (not specified) | Sunscreen of SPF 30 in the morning time | Sunscreen of SPF 50+ in the morning time |
| Duration of treatment follow-up | 12 weeks | 8 weeks | 8 weeks |
| Funding | Research Deputy of Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran | Not reported | Not reported |
| Overall risk of bias | High | High | High |
a
Values express as number (%) unless otherwise specified.
Abbreviations: MASI, melasma area and severity index; SD, standard deviation; SPF, sun protection factor.