Saw Palmetto (Serenoa repens)

Saw palmetto is used to treat symptoms associated with benign prostatic hypertrophy (BPH), a condition found in approximately 40% of men in their 50s and 90% of men in their 80s.^[80] In Europe, it is often used as first-line treatment for BPH.^[81] The major constituents of saw palmetto are fatty acids and their glycerides (i.e., triacylglycerides and monoacylglycerides), carbohydrates, steroids, flavonoids, resin, pigment, tannin, and volatile oil. The pharmacologic activity of saw palmetto has not been attributed to a single compound.

The mechanism of action of saw palmetto is not known, but multiple mechanisms based on available research have been proposed.^[82] In vitro data support the widely held belief that saw palmetto extract, like finasteride, inhibits 5α-reductase.^[83] However, in vivo studies have been inconsistent.^[82] Another hypothesis is that saw palmetto exerts its effects by inhibiting dihydrotestosterone binding to the androgen receptors in the prostate.^[84] Other proposed mechanisms are inhibition of estrogen receptors,^[85] blocking prolactin receptor signal transduction,^[86] interference with fibroblast proliferation,^[87] induction of apoptosis,^[88] inhibition of α₁ -adrenergic receptors,^[89] and anti-inflammatory effects.^{[90] [91]}

In a patient undergoing a craniotomy, saw palmetto was associated with excessive intraoperative bleeding that required termination of the procedure. ^[92] This complication was attributed to saw palmetto's anti-inflammatory effects, specifically the inhibition of cyclooxygenase and subsequent platelet dysfunction. Because there are no pharmacokinetic data for saw palmetto, specific recommendations for preoperative discontinuation cannot be made.