Jatenzo Dosing for Black and African Ancestry Patients: What Clinicians Need to Know

Why Ancestry Matters for Jatenzo Prescribing

Black and African ancestry patients are not simply a demographic subgroup. They carry population-specific pharmacogenomic variants, higher rates of hypertension, and a distinct pattern of end-organ risk that changes the calculus of any testosterone replacement regimen.

Jatenzo, approved by the FDA in March 2019, is the first oral testosterone undecanoate formulated for lymphatic absorption via the gastrointestinal tract, bypassing first-pass hepatic metabolism. That absorption mechanism depends on dietary fat and is subject to CYP3A4/5-mediated clearance. Both of those biological determinants vary across ancestries.

The sections below walk through every clinically actionable dimension: blood pressure, dose titration, pharmacogenomics, renal function, and lab monitoring.

The FDA Blood Pressure Warning in Context

The Jatenzo prescribing information carries a boxed-adjacent warning noting that the drug can cause blood pressure increases that may increase the risk of major adverse cardiovascular events (MACE) [1]. This is not merely a precaution to file away.

In the key Phase 3 study by Swerdloff et al. (J Clin Endocrinol Metab, 2020; N=166 hypogonadal men), mean systolic blood pressure rose by approximately 3 to 5 mmHg over the 52-week treatment period [1]. The trial was not powered or stratified by race, so ancestry-specific effect sizes are not reported. That gap is clinically meaningful, because a 3 to 5 mmHg systolic rise sits on top of a baseline that is already elevated in a population where 56% of Black adults have hypertension compared with roughly 44% of white adults [2].

Baseline Hypertension Prevalence and Its Clinical Weight

The CDC's 2021 National Health Interview Survey data place hypertension prevalence among non-Hispanic Black adults at approximately 56%, compared with a national average of 48% [2]. Black adults also experience hypertension onset at younger ages and sustain higher rates of hypertensive emergencies, heart failure, and hypertensive nephrosclerosis.

Starting Jatenzo in a Black patient who already has stage 1 hypertension is not automatically contraindicated. It does, however, require a documented blood pressure reading below 160/90 mmHg at baseline, a clear antihypertensive plan, and a follow-up visit within 4 weeks of initiation, rather than the 8 to 12 weeks that might be reasonable in a patient with no cardiovascular risk factors.

Standard Jatenzo Dose Titration: The Protocol That Applies to Everyone

Every patient, regardless of ancestry, begins on the same FDA-labeled starting dose. The titration ladder is driven by serum testosterone levels, not by demographic characteristics.

Starting Dose and Meal Requirements

The recommended starting dose is 158 mg oral TU (one soft-gelatin capsule) taken twice daily with a fat-containing meal [1]. Fat is required. A fat-free meal reduces peak testosterone (C-max) by approximately 10 to 20%, and the prescribing information explicitly states that Jatenzo must not be taken on an empty stomach.

At least 20 grams of dietary fat per meal is the clinical consensus target. Standard patient counseling examples: two eggs with cheese, a tablespoon of peanut butter, or a handful of mixed nuts with yogurt.

Titration Decision Points

Serum testosterone is measured as a trough concentration approximately 6 hours after the morning dose, at weeks 3 to 5 of therapy [1]. The titration rules are:

• Trough testosterone <350 ng/dL: increase dose to 237 mg twice daily
• Trough testosterone 350 to 650 ng/dL: maintain 158 mg twice daily
• Trough testosterone >650 ng/dL: decrease dose or discontinue

The upper available doses are 237 mg and 396 mg twice daily. Once dose is stable, testosterone is rechecked every 6 to 12 months per standard TRT monitoring guidelines from the Endocrine Society [3].

When to Delay or Defer Titration in High-Risk Patients

In a Black patient with baseline systolic blood pressure above 140 mmHg, dose escalation should not proceed based on testosterone level alone. Blood pressure must be re-assessed at the same visit as the week 3 to 5 testosterone draw. If systolic has risen more than 10 mmHg from baseline, the clinician should stabilize BP before increasing TU dose, even if testosterone remains subtherapeutic.

This approach is not specified in the Jatenzo label but is consistent with the FDA's MACE guidance and with AHA/ACC 2017 Stage 1 hypertension management thresholds [4].

Pharmacogenomics: Where African Ancestry Creates Real Variability

This section outlines a decision framework for integrating pharmacogenomic context into Jatenzo prescribing for Black and African ancestry patients. No commercially available pharmacogenomic panel currently includes an oral testosterone undecanoate-specific gene-drug interaction, but the relevant biology is established enough to inform clinical caution.

CYP3A4 and CYP3A5 Polymorphisms

Oral TU is primarily metabolized by CYP3A4 and, to a lesser degree, CYP3A5 after lymphatic absorption into systemic circulation [5]. CYP3A5 is a particularly important enzyme in this context: the CYP3A5*1 allele (the functional, high-expression variant) is present in approximately 60 to 70% of individuals of African ancestry, compared with roughly 10 to 20% of Europeans [5, 6].

Higher CYP3A5 expression means faster systemic clearance of testosterone undecanoate metabolites. This could theoretically produce lower trough testosterone concentrations in Black patients at a given nominal dose, pushing them more quickly toward the dose-escalation threshold at their week 3 to 5 check.

No published RCT has prospectively tested this hypothesis for Jatenzo specifically. The STEP-equivalent trial for oral TU has not been conducted with race-stratified pharmacokinetic endpoints. PharmGKB lists CYP3A4 as a pharmacokinetic gene for testosterone products [6], but the evidence level for specific ancestral dose adjustment remains low. What a clinician can reasonably do is expect that some Black patients may need dose escalation more readily and should not have that finding attributed to non-adherence before pharmacokinetic factors are considered.

G6PD Deficiency: A Separate Vigilance Layer

Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects approximately 10 to 14% of Black males and roughly 4% of Black females who carry one variant allele [7]. G6PD deficiency is not a contraindication to testosterone therapy. The enzyme is not directly involved in androgen metabolism.

The relevance here is indirect. Many Black patients prescribed Jatenzo will also require antihypertensive therapy. Certain drugs commonly added to manage Jatenzo-induced BP elevation, including nitrofurantoin and dapsone, are hemolytic triggers in G6PD-deficient patients. Rasburicase, used in some oncologic co-morbidities, is the highest-risk agent. The clinical instruction is simple: obtain G6PD status at baseline or before adding any hemolytic-risk agent to the medication list of a patient on Jatenzo who has Black or African ancestry.

SLCO1B1 and Testosterone Transport

SLCO1B1, which encodes the hepatic uptake transporter OATP1B1, influences the hepatic disposition of numerous drugs. Variants in SLCO1B1 are more common in African-ancestry populations and have been studied in the context of statin myopathy [8]. The transporter's role in testosterone undecanoate handling is not yet well characterized, but because TU undergoes some hepatic recirculation, SLCO1B1 variants are a plausible source of inter-individual variability. This is an area of active pharmacogenomic research rather than established clinical guidance.

Blood Pressure Management Co-Strategies for Black Patients on Jatenzo

The AHA/ACC 2017 hypertension guidelines recommend thiazide diuretics or calcium channel blockers (CCBs) as preferred first-line agents in Black patients without heart failure or chronic kidney disease, rather than ACE inhibitors or ARBs used as monotherapy [4]. The rationale is well-established: Black patients have lower plasma renin activity on average, making renin-angiotensin-aldosterone system (RAAS) inhibitors less effective in isolation for this population.

This has direct relevance to Jatenzo prescribing because some clinicians default to an ACE inhibitor or ARB when testosterone-related blood pressure elevation appears, without considering the evidence on differential efficacy.

Preferred Antihypertensive Choices

For a Black patient on Jatenzo who develops new or worsened hypertension, the preferred initial agents are:

• Chlorthalidone 12.5 to 25 mg daily (thiazide-like diuretic; superior to HCTZ for 24-hour BP control per ALLHAT [9])
• Amlodipine 5 to 10 mg daily (dihydropyridine CCB; first-line in Black patients per ACC/AHA guidance [4])

ACE inhibitors remain appropriate if the patient has comorbid conditions such as albuminuria or established heart failure with reduced ejection fraction, but should not be used as the sole agent when those specific indications are absent.

Monitoring Schedule

| Timepoint | Action | |---|---| | Baseline | Seated BP ×2, fasting lipids, serum creatinine, eGFR, urine albumin-to-creatinine ratio | | Week 3 to 5 | Serum testosterone trough, seated BP, symptom review | | Month 3 | Seated BP, repeat labs if BP was elevated at week 3 to 5 | | Month 6 | Serum testosterone, full metabolic panel, hematocrit | | Annually | All of the above plus PSA, digital rectal exam if indicated by age/risk |

Renal Considerations in Black and African Ancestry Patients

Black adults develop end-stage renal disease (ESRD) at approximately 3.4 times the rate of white adults in the United States [10]. The reasons are multifactorial: higher hypertension prevalence, higher rates of diabetic nephropathy, genetic variants in APOL1, and historical barriers to early CKD detection.

Testosterone and its metabolites promote sodium and water retention through direct effects on renal tubular sodium channels and through secondary increases in erythropoietin-driven blood viscosity. In a patient with CKD stage 3 or above, even a modest increase in sodium retention can accelerate progression and worsen blood pressure control.

APOL1 Risk Variants and CKD Velocity

Approximately 13% of African Americans carry two high-risk APOL1 variants (G1/G1, G2/G2, or G1/G2 genotype), which confer a 7 to 10 fold increased lifetime risk of focal segmental glomerulosclerosis (FSGS) and hypertensive nephrosclerosis compared with low-risk genotypes [11]. APOL1 testing is not yet standard of care outside nephrology referral settings, but knowing that a Black patient is at elevated CKD risk should lower the threshold for checking urine albumin-to-creatinine ratio before and during Jatenzo therapy.

A urine ACR above 30 mg/g (microalbuminuria) should prompt nephrology co-management before escalating testosterone dose, regardless of serum creatinine.

Erythrocytosis and Hyperviscosity

Testosterone causes dose-dependent erythrocytosis. The Endocrine Society guideline (2018) recommends holding or dose-reducing TRT when hematocrit exceeds 54% [3]. In a patient with CKD-related baseline anemia who normalizes on TU, the hematocrit trajectory may be rapid and require monitoring at month 3 rather than month 6. Hyperviscosity in the setting of elevated blood pressure is a compounding MACE risk factor.

Evidence Gaps and What the Swerdloff 2020 Trial Does (and Does Not) Tell Us

The key Jatenzo Phase 3 study, Swerdloff et al. 2020, enrolled 166 hypogonadal men across multiple U.S. Sites over 52 weeks [1]. The primary endpoint was the percentage of patients achieving average serum testosterone concentrations within the normal range (300 to 1,000 ng/dL) after dose adjustment. The trial achieved that endpoint: 87% of participants reached normal-range testosterone.

The trial did not report race-stratified pharmacokinetic data, race-stratified blood pressure outcomes, or subgroup analyses by ancestry. This is a gap shared by most TRT trials published before 2022 and reflects a broader problem in endocrinology research: ancestral diversity in trial populations has historically been insufficient to generate subgroup-level conclusions.

"The available evidence supports the efficacy and relative safety of testosterone replacement therapy in hypogonadal men, but significant data gaps remain for populations defined by race, ethnicity, and underlying genetic polymorphisms," per an Endocrine Society position statement on research priorities [3].

What the Swerdloff 2020 data can support is the assertion that mean BP elevation of 3 to 5 mmHg is the expected pharmacodynamic signature of Jatenzo across the studied population. For a Black patient sitting at a higher baseline BP, the same 3 to 5 mmHg rise lands in a more dangerous absolute zone. A systolic of 128 mmHg pushed to 133 mmHg is manageable. A systolic of 148 mmHg pushed to 153 mmHg crosses a treatment threshold and may require antihypertensive initiation or intensification.

Practical Clinical Workflow for Initiating Jatenzo in Black and African Ancestry Patients

The following sequence consolidates the evidence above into a concrete clinical pathway.

Step 1: Pre-Initiation Risk Stratification

Before writing the Jatenzo prescription:

• Document seated blood pressure from two separate visits (or one visit with two readings 5 minutes apart). Defer initiation if systolic is consistently above 160 mmHg until BP is controlled.
• Order serum creatinine, eGFR, and urine ACR. If eGFR is <45 mL/min/1.73 m², consult nephrology before starting.
• Review the full medication list for drugs that interact with CYP3A4 (strong inhibitors such as clarithromycin or itraconazole may raise TU exposure; inducers such as rifampin may reduce it dramatically).
• Ask about G6PD status if not already documented, particularly if the patient will likely need antihypertensive agents.

Step 2: Initiation at 158 mg Twice Daily

Start at the labeled dose. Provide written fat-meal instructions. The "fat-with-every-dose" instruction is not optional and should be reinforced at every visit for the first three months.

Step 3: Week 3 to 5 Visit (Extended for High-Risk Patients)

Measure testosterone trough and seated blood pressure at the same visit. Apply the titration rules above, but do not escalate dose if systolic BP has risen more than 10 mmHg from baseline regardless of testosterone level. Address blood pressure first, then re-evaluate testosterone at the next visit.

Step 4: Ongoing Monitoring

Follow the monitoring table in the Blood Pressure section above. Add a urine ACR check at month 6 if it was normal at baseline and the patient has developed hypertension or erythrocytosis during therapy. Hematocrit above 54% requires dose reduction or temporary interruption.

Summary Data Points Clinicians Should Have at the Bedside

Three statistics drive this entire protocol:

1. In Swerdloff et al. 2020 (N=166), Jatenzo produced a mean systolic BP rise of approximately 3 to 5 mmHg over 52 weeks, with 87% of patients achieving normal-range serum testosterone [1].

2. The CYP3A5*1 high-expression allele is present in 60 to 70% of individuals of African ancestry, compared with 10 to 20% of Europeans, a difference that may accelerate TU clearance and shift dose requirements upward for a meaningful proportion of Black patients [5, 6].

3. Black adults in the U.S. Develop ESRD at 3.4 times the rate of white adults [10], making renal surveillance during androgen therapy a higher-yield intervention in this population than in lower-risk groups.

No ancestral subgroup has been prospectively studied in a Jatenzo-specific pharmacokinetic trial. Until that evidence exists, clinical judgment must bridge the gap using population pharmacogenomics, cardiology guideline recommendations for Black patients, and a more compressed monitoring schedule than the label alone would suggest.

The Endocrine Society's 2018 testosterone therapy guideline states: "We recommend measuring hematocrit at baseline and at 3 to 6 months and then annually" [3]. In a Black patient with CKD risk factors, checking hematocrit at 3 months rather than 6 months is the more conservative and defensible approach given the additional sodium-retention and hyperviscosity risks outlined above.