Sai Michael Biotech's entry here is the urological strength of finasteride: 5 mg per tablet, fifty tablets to the box. Five milligrams is the concentration originally registered for benign prostatic hyperplasia, where the object is reducing prostate volume rather than preserving hair follicles.
Mechanically it is the same type II 5-alpha-reductase inhibitor as the 1 mg product, with five times the active per tablet. It is taken orally, and its suppression of the enzyme lasts considerably longer than the plasma half-life of the drug would suggest.
