One of the challenges in managing hair disorders is that significant improvement will not instantly be visible since hair grows slowly (~1cm monthly) (1). Hence, there is a continuous quest to discover treatment modalities that promote hair growth, like topical minoxidil and finasteride.
This article focuses on another group of drugs with potential as a hair growth stimulant, the prostaglandin analogues (latanoprost and bimatoprost).
What are prostaglandins?
Prostaglandins (PG) are lipids formed from the metabolism of arachidonic acid and other long-chain fatty acids via cyclooxygenase (COX) actions. Different prostaglandins act like hormones that bind to receptors modulating different body physiological processes (2).
The hair follicle, a mini-organ itself, is affected by PGs since their receptors are found in almost all of its parts. Among the PGs, prostaglandin D2 (PGD2) and prostaglandin F2 α (PGDF2 α) are the ones linked to hair growth, with the latter being stimulatory (see figure 1) (2).
Prostaglandins F2a analogues for hair growth
Sometimes accidents are meant to be! In 1997, PGs’ potential role in the treatment for hair loss was serendipitously discovered among patients with glaucoma on latanoprost drops, a PGDF2 α analog (3).
Latanoprost was noted to increase the amount, length, thickness, curvature, and even color intensity of eyelashes (3). The eyelash growth was more prominent in bimatoprost patients than latanoprost (4, 5). Similar findings were also noted in travoprost (4, 6).
Even though the exact mechanism is unknown, it has been established that prostaglandin F2 α analogs cause hair growth by stimulating and extending the anagen (growing) phase, increasing the proportion of anagen compared to catagen and telogen hair (2, 7). Hence, most hair strands remain long, coarse, and darker (terminal hair).
Furthermore, eyelashes of patients with alopecia areata (AA) Universalis grew with latanoprost treatment. Bimatoprost was found to be effective in treating eyelash AA Universalis as well as eyelash and eyebrow thinning and chemotherapy-induced madarosis (loss of eyebrows or lashes) (5).
Furthermore, Latisse®, along with other brands (Bimatoprost 0.003%), already received US Food and Drug Administration approval to treat patients with eyelash hypotrichosis (little or no hair growth ).
Can the actions of these prostaglandin analogues go beyond luscious lashes?
Prostaglandins F2a analogues as a treatment for scalp hair loss
Studies regarding the use of prostaglandin analogues to treat hair loss disorders are promising. In a placebo-controlled clinical trial, 0.1% latanoprost was found to increase hair density of both vellus and terminal hair in men, with mild androgenetic alopecia (Hamilton II-III), after 24 weeks of treatment (8).
However, injected 0.03% bimatoprost solution was not effective in a patient with female-patterned baldness (9).
In patients with alopecia areata, bimatoprost 0.03% solution applied twice daily exhibited better results in terms of hair regrowth percentage and rapidity of treatment response than mometasone furoate 0.1% cream a mid-strength (class 4) topical steroid, after three months of application (10).
In another study, latanoprost 0.005% solution applied twice daily for eight weeks resulted in hair growth in bald patches of alopecia areata (AA) but was inferior compared to betamethasone dipropionate 0.05% lotion, an upper mid-strength (class 3) topical steroid, applied twice a day (11).
Using latanoprost in combination with well-studied medications leads to better treatment outcomes.
Betamethasone valerate 0.1% solution, a mild (class 6) topical steroid, with latanoprost 0.1% lotion showed superior efficacy in the treatment of alopecia areata as opposed to monotherapy of minoxidil 5% lotion, betamethasone valerate, or latanoprost (12).
Furthermore, a mixture of 5% minoxidil (60ml) and 2.5 ml of 0.005% latanoprost (2.5 ml) solution was more effective in the treatment of patchy alopecia areata than minoxidil alone (13).
This implies that latanoprost is more effective when used with a topical steroid or minoxidil in the treatment of alopecia areata.
Side effects of prostaglandins analogues
Latanoprost and bimatoprost are generally safe, more so, if used topically on the scalp. Since they have been widely used as ophthalmic drops, reported side effects are mainly on the eyes, like itchiness, conjunctival redness, irritation, dryness, and eyelid darkening (2, 14).
Other adverse reactions are blood-aqueous barrier damage, macular edema, uveitis, and herpes simplex viral infection (2, 14). Most side effects are reversible except for increased pigmentation of the iris (14).
Latanoprost 0.005% solution was well-tolerated than betamethasone dipropionate 0.05% lotion when applied twice a day for eight weeks in bald patches of alopecia areata (11). In this study, erythema was the only observed side effect of latanoprost (11).
Products with prostaglandins analogues for hair loss
In most dermatologic conditions, combination treatments enhance and hasten treatment response or improvement.
Besides the mainstay, topical steroids in alopecia areata or anti-androgen drugs for androgenetic alopecia, topical medications that promote hair growth like minoxidil are also given to patients. Adding another hair growth stimulant, like PGDF2 α analogues, may also be beneficial.
There are hair products with latanoprost that are being marketed for scalp hair. These products are usually in compounded solutions or foams for easy application and with other medications that stimulate hair growth. Available products with latanoprost are the following:
1. Latanoprost/ Minoxidil/ Finasteride topical foam/ solution (cfspharmacy.pharmacy)
This product has both latanoprost and minoxidil, which both extend the anagen phase, and a 5-alpha reductase inhibitor finasteride, which prevents hair miniaturization in androgenetic alopecia or male-pattern baldness.
2. Hair restore MML scalp solution (empowerpharmacy.com)
This solution has 3% minoxidil, 0.01% latanoprost and 0.2% melatonin. Melatonin solution was found to increase the number of anagen hair among females with androgenetic alopecia or hair thinning from telogen effluvium or excessive hair shedding (>100 strands), making this preparation suitable to females with similar conditions (15).
3. Hair restore LF (evolvecompanyinc.com)
This contains 0.01% latanoprost and 0.1% finasteride, suitable for males with androgenetic alopecia or male-pattern baldness.
4. AnagenFx Kit (anagenfx.com)
This hair grower kit is comprised of the following:
To sum up, more studies with larger sample size, longer duration of treatment, and higher medication concentration are needed to secure the role of prostaglandin analogues in treating hair loss disorders (2).
But the luscious eyelashes that these drugs cause hold the promise of their efficacy even as a complementary treatment to achieve the glorious scalp hair that everyone aims for.