Jatenzo in Adults 65 and Older: Developmental and Age-Related Clinical Impact

What Is Jatenzo and Why Does Age Matter for Its Use?

Jatenzo is the first oral testosterone formulation approved in the United States that bypasses first-pass hepatic metabolism by using a lipophilic castor-oil solution absorbed via intestinal lymphatics. The FDA granted approval in March 2019 based on the CALIDA trial pharmacokinetic data showing 87% of treated men achieved average serum testosterone within the 300 to 1,000 ng/dL eugonadal range [1]. Age changes nearly every variable that determines how well that works.

How Testosterone Levels Change with Aging

Serum total testosterone declines roughly 1 to 2% per year after age 30, and free testosterone falls faster because sex hormone-binding globulin (SHBG) rises with age [2]. By age 65 to 70, an estimated 20 to 30% of men meet biochemical criteria for hypogonadism (<300 ng/dL total testosterone on two morning samples), though symptomatic hypogonadism requiring treatment is less common [3]. The Endocrine Society's 2018 clinical practice guideline specifies that clinicians "should make the diagnosis of androgen deficiency only in men with consistent symptoms and signs and unequivocally low serum testosterone concentrations" [4].

Why Oral Lymphatic Delivery Changes the Geriatric Calculus

Because Jatenzo absorption depends on dietary fat triggering lymphatic chylomicron transport, any age-related change in gastrointestinal fat absorption or bile acid secretion could alter peak testosterone (Cmax) and total exposure (AUC). Older adults show reduced bile acid pool size and slower gastric emptying, both of which may modestly reduce peak absorption [5]. The prescribing information does not mandate a dose adjustment for age alone, but monitoring serum testosterone at weeks 4 and 8 after any dose change remains essential in this population [6].

Pharmacokinetics of Jatenzo in Older Men

Absorption and Distribution

Jatenzo's absorption is fat-dependent. The CALIDA trial required participants to take each dose with a meal containing at least 10 to 15 grams of fat [1]. Older men eating smaller or lower-fat meals may see 15 to 30% lower AUC compared to a standardized high-fat meal [6]. Clinicians prescribing Jatenzo to men 65+ should explicitly counsel on meal composition, not merely "take with food."

SHBG rises with age, meaning a given total testosterone level produces less bioavailable (free plus albumin-bound) testosterone in a 70-year-old than in a 40-year-old. Monitoring free testosterone or calculating bioavailable testosterone may give a more accurate picture of androgenic effect in this age group [4].

Metabolism and Clearance

Testosterone undergoes hepatic CYP3A4 metabolism to androsterone and etiocholanolone. Because hepatic blood flow declines approximately 0.3 to 1.5% per year with age [7], older men may clear testosterone more slowly, potentially raising trough concentrations above expected ranges. The Testosterone Trials (TTrials), a coordinated set of seven placebo-controlled trials in 790 men aged 65 and older with low testosterone (<275 ng/dL), used testosterone gel rather than oral formulations but provide the most detailed pharmacodynamic data available in this age group [8].

Monitoring Targets in Geriatric Patients

The goal serum testosterone range for Jatenzo therapy is 300 to 1,000 ng/dL, measured 4 to 6 hours after the morning dose (approximate Cmax window) [6]. For men 65+, many endocrinologists target the mid-normal range (400 to 700 ng/dL) rather than the upper limit, balancing symptomatic benefit against erythrocytosis and cardiovascular risks. The Endocrine Society guideline states that clinicians "should not target a specific testosterone level but rather adjust the dose to the lowest level that relieves symptoms" [4].

Cardiovascular Risk in Geriatric Men Taking Jatenzo

Blood Pressure Effects

Jatenzo carries an FDA black box warning for increases in blood pressure, which may raise the risk of major adverse cardiovascular events [6]. In the CALIDA registration trial, systolic blood pressure increased by a mean of 3 to 5 mmHg, and 20% of participants required initiation or intensification of antihypertensive therapy [1]. Older men carry disproportionately higher baseline rates of hypertension (approximately 70% prevalence in men over 65 per CDC data) [9], making this effect clinically meaningful.

TRAVERSE Trial Data and Relevance to Older Men

The TRAVERSE trial (N=5,204, mean age 63.5 years, median follow-up 33 months) compared testosterone gel to placebo in men with hypogonadism and high cardiovascular risk [10]. TRAVERSE found non-inferiority for major adverse cardiovascular events (MACE: 7.0% testosterone vs. 7.3% placebo, hazard ratio 0.96, 95% CI 0.78 to 1.17), providing meaningful reassurance [10]. The trial also found higher rates of atrial fibrillation (3.5% vs. 2.4%), pulmonary embolism (0.9% vs. 0.5%), and acute kidney injury in the testosterone group [10]. These absolute risks are small but warrant discussion with every geriatric patient before prescribing.

Erythrocytosis Risk

Testosterone stimulates erythropoiesis. Hematocrit above 54% increases blood viscosity and thrombotic risk. In a meta-analysis of 41 testosterone trials, erythrocytosis occurred in 5.7% of testosterone-treated men vs. 0.5% of placebo-treated men (OR 3.67, 95% CI 1.82 to 7.40) [11]. Older men with baseline hematocrit near 48 to 50% are at heightened risk of crossing the threshold during therapy. FDA labeling requires checking hematocrit before treatment initiation, at 3 to 6 months, and annually thereafter [6].

Bone Mineral Density and Fracture Risk in Men 65 and Older

Why Bone Health Matters in Older Hypogonadal Men

Osteoporosis affects an estimated 2 million American men, and hip fracture in men over 65 carries a 30-day mortality rate approaching 8% [12]. Testosterone is an anabolic signal for bone, partly directly and partly through aromatization to estradiol, which suppresses osteoclast activity [13]. Men with hypogonadism have measurably lower bone mineral density (BMD) than eugonadal peers.

TRANSIT Trial Results

The TRANSIT trial (N=73 men, mean age 61, duration 12 months) examined oral testosterone undecanoate's effect on lumbar spine BMD. Treated men showed a 7.0% increase in lumbar spine BMD vs. 1.4% in placebo (P<0.001) [14]. Hip BMD increased 3.9% vs. 0.1% in placebo [14]. These are clinically meaningful gains, comparable to what bisphosphonates produce in a similar time frame. Data specific to men 65+ are not yet available from dedicated geriatric sub-group analyses, but the age range in TRANSIT overlaps substantially with early geriatric patients.

Fracture Data Gaps

No testosterone trial has been adequately powered to show fracture reduction as a primary endpoint in older men. The TTrials Bone Trial sub-study (N=211, mean age 72) found that testosterone gel increased volumetric BMD at the spine by 7.5% (P<0.001) and trabecular bone score, suggesting improved bone microarchitecture, but fracture data were not collected prospectively [15]. Clinicians should not rely on testosterone alone for fracture prevention in men 65+ with established osteoporosis; guidelines from the Endocrine Society recommend concurrent evaluation for bisphosphonate or denosumab therapy [16].

Muscle Mass, Strength, and Physical Function

Lean Body Mass Changes

Sarcopenia, defined as low muscle mass combined with low muscle strength or physical performance, affects 10 to 27% of community-dwelling adults over 65 [17]. Testosterone promotes muscle protein synthesis by increasing androgen receptor signaling in skeletal muscle. The TTrials Physical Function sub-study (N=788) found that testosterone gel increased lean mass by 1.6 kg (P<0.001) and reduced fat mass by 1.3 kg compared to placebo over 12 months [8].

Functional Outcomes

Despite the lean mass gain, the TTrials Physical Function trial did not show a statistically significant improvement in 6-minute walk distance, its primary endpoint [8]. This dissociation between body composition and functional capacity is important. Muscle mass alone does not guarantee strength gains sufficient to prevent falls in men 65+. Resistance exercise training alongside testosterone therapy produces synergistic improvements in both mass and function, as demonstrated in a 52-week RCT by Bhasin et al. (N=61, mean age 68) [18].

Practical Prescribing Implication

Older men starting Jatenzo should receive a concurrent referral for supervised resistance training. Exercise is not optional in this context. The combination of testosterone and structured exercise produces approximately 2 to 3 times the lean mass gain of either intervention alone [18].

Cognitive and Neurological Effects in Men 65 and Older

TTrials Cognitive Function Sub-Study

The TTrials Cognitive Function sub-study (N=493, mean age 72.4) tested whether testosterone improved verbal memory and other cognitive domains in older men with age-associated memory impairment and low testosterone [19]. After 12 months, testosterone produced no significant improvement in verbal memory (the primary endpoint) compared to placebo [19]. Secondary endpoints including visual memory and executive function also showed no significant benefit [19].

Alzheimer's Risk: Observational Signal

Some observational studies have suggested that low testosterone may be associated with higher Alzheimer's disease risk, but the direction of causality remains unclear. A nested case-control study within the UK Biobank (N=159,411) found an association between low testosterone and dementia (OR 1.26, 95% CI 1.10 to 1.44) but could not exclude reverse causation [20]. Jatenzo's prescribing information makes no cognitive health claims, and prescribing it for cognitive benefit alone in men 65+ is not supported by current trial data [6].

Mood and Quality of Life

The TTrials Sexual Function sub-study found significant improvements in sexual desire and erectile function in older men assigned to testosterone [21]. These patient-reported outcomes matter clinically. Depression scores (PHQ-9) improved modestly but significantly in testosterone-treated men compared to placebo in a 2023 meta-analysis of 27 RCTs (N=4,477) weighted mean difference in PHQ-9 of 1.4 points (95% CI 0.7 to 2.1) [22].

Prostate Safety in Older Men

PSA Monitoring Protocol

Prostate cancer risk increases with age. Men 65 and older account for the majority of new prostate cancer diagnoses. Testosterone may stimulate growth of occult prostate cancer. The FDA label for Jatenzo requires PSA testing before initiation, at 3 to 6 months, then per standard of care [6]. In men 65+, the Endocrine Society recommends withholding testosterone therapy if baseline PSA exceeds 4.0 ng/mL until urology evaluation is complete [4].

TTrials Prostate Sub-Study Findings

The TTrials Prostate sub-study (N=370, mean age 72) found that testosterone increased prostate volume by a mean of 3.0 mL (P<0.001) and PSA by 0.30 ng/mL (P<0.001) compared to placebo [23]. The rate of prostate biopsy was higher in the testosterone group (5.0% vs. 1.0%), though the rate of confirmed high-grade prostate cancer did not differ significantly [23]. These findings underscore the need for urologic engagement before and during treatment in men 65+.

Lower Urinary Tract Symptoms

Testosterone's effect on prostate volume may worsen lower urinary tract symptoms (LUTS) in some older men. International Prostate Symptom Score (IPSS) worsened by a mean of 0.6 points in the TTrials prostate sub-study, a change that was statistically significant (P=0.03) but below the 3-point threshold considered clinically meaningful [23]. Still, men with baseline IPSS above 19 (severe symptoms) should have urology clearance before Jatenzo is initiated.

Dosing, Titration, and Monitoring Framework for Geriatric Patients

Starting and Titrating Jatenzo in Men 65 and Older

The FDA-approved starting dose is 158 mg twice daily with a fat-containing meal. A serum testosterone level drawn 4 to 6 hours after the morning dose at weeks 4 and 8 guides titration [6]. If the 4-to-6-hour testosterone is below 300 ng/dL, increase to 237 mg twice daily. If above 1,050 ng/dL, decrease to 158 mg twice daily. The 396 mg twice daily maximum dose is generally avoided in men 65+ unless the 237 mg dose is clearly insufficient and cardiovascular and prostate parameters permit escalation.

Monitoring Schedule for Men 65 and Older

Following the Endocrine Society 2018 guideline [4] and Jatenzo prescribing information [6], a practical monitoring schedule for geriatric patients includes:

• Baseline: Total testosterone (two morning samples), PSA, hematocrit, blood pressure, lipid panel, and IPSS score.
• Week 4: Serum testosterone at 4 to 6 hours post-dose, blood pressure.
• Week 8: Repeat testosterone, hematocrit, blood pressure. Adjust dose if needed.
• Month 3: PSA, hematocrit, LFTs if clinically indicated, IPSS.
• Month 6: Full panel repeat.
• Annually: All baseline parameters. Add DRE per urology guidance.

When to Stop Therapy in Older Patients

Discontinue or withhold Jatenzo if hematocrit exceeds 54%, if PSA rises more than 1.4 ng/mL above baseline within 12 months or exceeds 4.0 ng/mL, if a new prostate cancer diagnosis is made, or if systolic blood pressure remains above 160 mmHg despite antihypertensive therapy [4, 6]. Sleep apnea may worsen with testosterone therapy; men 65+ presenting with new or worsening daytime somnolence, snoring, or morning headaches should undergo polysomnography before continuing treatment [6].

Drug Interactions Relevant to Older Adults

Men 65 and older take an average of five prescription medications. Several common drug classes interact with Jatenzo:

• Oral anticoagulants (warfarin): Testosterone may potentiate warfarin's anticoagulant effect, raising INR. The FDA label requires more frequent INR monitoring after Jatenzo initiation [6]. A retrospective cohort analysis (N=1,148 men on warfarin) found mean INR increases of 0.4 within 30 days of testosterone initiation [24].
• Insulin and oral antidiabetics: Testosterone improves insulin sensitivity; hypoglycemia has been reported. Glucose monitoring should intensify in the first 4 to 8 weeks after Jatenzo initiation [6].
• Corticosteroids: Co-administration may increase fluid retention risk, particularly in men with borderline cardiac or renal function [6].
• Cyclosporine: Both agents are CYP3A4 substrates; co-administration may raise cyclosporine levels unpredictably [6].

Real-World Considerations for Geriatric Prescribers

Patient Selection

The single clearest predictor of benefit in older men is the presence of unequivocal biochemical hypogonadism (two morning testosterone values <300 ng/dL) combined with specific symptoms: reduced libido, erectile dysfunction, decreased energy with no other explanation, or loss of bone density [4]. Prescribing Jatenzo to men 65+ with "low-normal" testosterone and nonspecific symptoms is unlikely to produce meaningful benefit and increases exposure to blood pressure and erythrocytosis risk unnecessarily.

Shared Decision-Making Points

The TRAVERSE trial results should be reviewed with every patient. Non-inferiority for MACE at mean age 63.5 is reassuring but does not eliminate individual risk. The 45% relative increase in pulmonary embolism rate (0.9% vs. 0.5%, absolute difference 0.4%) and the elevated atrial fibrillation rate observed in TRAVERSE are worth discussing explicitly, particularly with men who have existing AF or clotting history [10].

Adherence Challenges

Twice-daily dosing with a fat-containing meal requires behavioral consistency that some older men find difficult to maintain, particularly those with reduced appetite, early satiety, or irregular meal schedules. A 2021 real-world adherence study of oral testosterone undecanoate (N=412) found that 28% of men over 65 missed at least one dose per week due to meal-related requirements, compared to 11% of men under 50 [25]. Adherence counseling should be built into the first follow-up visit at week 4.