General Information

Jatenzo (testosterone undecanoate) is an endogenous androgen.

Jatenzo is specifically indicated for testosterone replacement therapy in adult males for conditions associated with a deficiency or absence of endogenous testosterone.

Jatenzo is supplied as a capsule for oral administration. Prior to initiating Jatenzo, confirm the diagnosis of hypogonadism by ensuring that serum testosterone concentrations have been measured in the morning on at least two separate days and that these concentrations are below the normal range. Take Jatenzo with food. The starting dose is 237 mg orally once in the morning and once in the evening. Adjust the dose to a minimum of 158 mg twice daily and a maximum of 396 mg twice daily based on serum testosterone drawn 6 hours after the morning dose at least 7 days after starting treatment or following dose adjustment and periodically thereafter. 

Mechanism of Action

Jatenzo (testosterone undecanoate) is an endogenous androgen. Endogenous androgens, including testosterone and dihydrotestosterone (DHT), are responsible for the normal growth and development of the male sex organs and for maintenance of secondary sex characteristics. These effects include the growth and maturation of prostate, seminal vesicles, penis and scrotum; the development of male hair distribution, such as facial, pubic, chest and axillary hair; laryngeal enlargement, vocal cord thickening, alterations in body musculature and fat distribution. Male hypogonadism, a clinical syndrome resulting from insufficient secretion of testosterone, has two main etiologies. Primary hypogonadism is caused by defects of the gonads, such as Klinefelter syndrome or Leydig cell aplasia, whereas secondary hypogonadism (also known as hypogonadotropic hypogonadism) is the failure of the hypothalamus (or pituitary) to produce sufficient gonadotropins (FSH, LH).

Side Effects

Adverse effects associated with the use of Jatenzo may include, but are not limited to, the following:

• polycythemia
• diarrhea
• dyspepsia
• eructation
• peripheral edema
• nausea
• increased hematocrit
• headache
• prostatomegaly
• hypertension

The Jatenzo drug label comes with the following Black Box Warning: Jatenzo can cause blood pressure (BP) increases that can increase the risk of major adverse cardiovascular events (MACE), including non-fatal myocardial infarction, non-fatal stroke and cardiovascular death. Before initiating Jatenzo, consider the patient’s baseline cardiovascular risk and ensure blood pressure is adequately controlled. Periodically monitor for and treat new-onset hypertension or exacerbations of pre-existing hypertension and re-evaluate whether the benefits of Jatenzo outweigh its risks in patients who develop cardiovascular risk factors or cardiovascular disease on treatment. Due to this risk, use Jatenzo only for the treatment of men with hypogonadal conditions associated with structural or genetic etiologies.

Clinical Trial Results

The FDA approval of Jatenzo was based on an open label study in 166 adult hypogonadal males of approximately 4 months duration. The study included a Screening Phase, a Treatment Titration Phase, and a Treatment Maintenance Phase. Jatenzo was taken orally at a starting dose of 237 mg twice per day with meals. The dose was adjusted on Days 21 and 56 between a minimum of 158 mg twice per day and a maximum of 396 mg twice per day on the basis of the average testosterone concentration obtained over 24 hours post-morning dose. The primary endpoint was the percentage of patients with mean plasma total testosterone concentration (Cavg) over 24-hours within the normal eugonadal range on the final PK visit of the study. Secondary endpoints were the percentage of patients with a maximum total testosterone concentration (Cmax) above three predetermined limits: less than or equal to 1500 ng/dL, between 1800 and 2500 ng/dL, and greater than 2500 ng/dL. One hundred and forty-five (87%) of the 166 hypogonadal men who received jatenzo had a mean total testosterone concentration (Cavg) within the normal eugonadal range at the end of treatment. The percentage of patients who received Jatenzo and had Cmax less than or equal to 1500 ng/dL, between 1800 and 2500 ng/dL, and greater than 2500 ng/dL at the final PK visit were 83%, 3%, and 3%, respectively.