Age Management Medicine News: August/September 2022 – #1

FDA Approves Oral Testosterone Replacement Therapy Kyzatrex

Brian Park, PharmD

August 2, 2022 ( – The Food and Drug Administration (FDA) has approved Kyzatrex (testosterone undecanoate) for testosterone replacement therapy in adult males for conditions associated with deficiency or absence of endogenous testosterone:

  • Primary hypogonadism (congenital or acquired): testicular failure due to conditions such as cryptorchidism, bilateral torsion, orchitis, vanishing testis syndrome, orchiectomy, Klinefelter syndrome, chemotherapy, or toxic damage from alcohol or heavy metals. These men usually have low serum testosterone concentrations and gonadotropins (follicle stimulating hormone [FSH], luteinizing hormone [LH]) above the normal range.
  • Hypogonadotropic hypogonadism (congenital or acquired): gonadotropin or luteinizing hormone-releasing hormone (LHRH) deficiency or pituitary-hypothalamic injury from tumors, trauma, or radiation. These men have low testosterone serum concentrations but have gonadotropins in the normal or low range.

The approval was based on data from an open-label, 6-month, phase 3 study ( Identifier: NCT04467697) that evaluated the efficacy and safety of Kyzatrex in 155 men with hypogonadism. Patients received Kyzatrex at a starting dose of 200mg twice daily with meals; the dosage was adjusted on days 28 and 56 based on plasma testosterone concentration.

Results showed that 88% (95% CI, 82-93) of patients treated with Kyzatrex achieved a 24-hour mean plasma total testosterone concentration within the normal range of 222-800ng/dL on the final pharmacokinetic (PK) visit at day 90 (primary endpoint). The percentage of patients who received Kyzatrex and had a maximum total testosterone concentration threshold less than or equal to 1200ng/dL, between 1400ng/dL and 2000ng/dL, and greater than 2000ng/dL at the final PK visit were 88%, 4%, and 0%, respectively.

As for safety, Kyzatrex carries a Boxed Warning regarding blood pressure increases that can increase the risk of major adverse cardiovascular events, including nonfatal myocardial infarction, nonfatal stroke and cardiovascular death. Due to this risk, Kyzatrex should only be used for the treatment of men with hypogonadal conditions associated with structural or genetic etiologies. The most common adverse reaction reported with Kyzatrex was hypertension.

Kyzatrex is a Schedule III controlled substance. The product is supplied as 100mg, 150mg, or 200mg of testosterone undecanoate capsules in 90-count bottles. It is not substitutable with other oral testosterone undecanoate products.


  1. Marius Pharmaceuticals receives FDA approval of Kyzatrex™, an oral testosterone replacement therapy. News release. Marius Pharmaceuticals. Accessed August 2, 2022.
  2. Kyzatrex. Package insert. Marius Pharmaceuticals; 2022. Accessed August 2, 2022.
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