This article may be useful in answering some of our questions.
Effect of cetirizine on mast cell-mediator release and cellular traffic during the cutaneous late-phase reaction.
Authors
Charlesworth EN, et al. Show all Journal
J Allergy Clin Immunol. 1989 May;83(5):905-12.
Affiliation
Department of Medicine, Johns Hopkins University School of Medicine, Good Samaritan Hospital, Baltimore, Md 21239.
Abstract
A new H1 antihistamine, cetirizine, was studied to determine its effects on mediators and cellular infiltration during the cutaneous late-phase response (LPR). Ten ragweed-allergic subjects, who had previously demonstrated a cutaneous LPR, were examined in a double-blind, crossover study. Either cetirizine, 20 mg, or placebo was administered orally once daily for 2 days before and the morning of placement of a skin chamber overlying an unroofed heat/suction-induced blister to which was added antigen or buffer. Skin test erythema was significantly reduced by cetirizine at 15 minutes, 2 hours, and 4 hours by 56%, 40%, and 39%, respectively (all, p less than or equal to 0.01), but by 6 and at 8 hours, the cutaneous erythema was not significantly lessened. Histamine release was not altered by cetirizine treatment, but prostaglandin D2 (PGD2) production, which peaked at 3 to 5 hours, was clearly reduced by cetirizine treatment, being lower at all time points during the reaction; this was significant by analysis of variance (p less than or equal to 0.04). The inhibition was most marked during the fifth hour of the reaction when there was a 50% suppression of the PGD2 level by cetirizine (0.193 ng/ml to 0.075 ng/ml [p less than or equal to 0.03]). The most dramatic effect of cetirizine was attenuation of the inflammatory cell migration into the chamber. Eosinophil infiltration was decreased by about 75% during hours 6, 7, and 8 (p less than or equal to 0.04), whereas the number of neutrophils was reduced by the same magnitude at the same times
Most improved results are seen with users applying cetirizine topically rather than ingesting orally.
I too wonder why this cheap OTC drugs can turn out to be a treatments for AGA, perhaps on its specific function on inhibiting only PGD2 and not other good prostaglandins i.e. PGE2 as what ibuprofen does in inhibiting all the prostaglandins.
Still too early to judge though. I had undergone ht 34 days ago by dr. pong in chiang mai and now I am taking finasteride and oral minoxidil daily. Went through some major shedding on my 3rd week post op and its stabilizing now.
I started applying topical cetirizine 2 days ago and it seems to help calming my scalp itch big time. My scalp itches even without applying minoxidil so you can imagine how big a relief it is.