Xyosted Dosing: 75 mg Weekly Subcutaneously
The typical dose of Xyosted is 75 mg administered subcutaneously in the abdominal region once weekly, with dose adjustments of 25 mg increments (to 50 mg, 75 mg, or 100 mg) based on testosterone trough levels measured at 6 weeks. 1
Starting Dose and Administration
- Initial dose: 75 mg subcutaneously once weekly
- Route: Subcutaneous injection in the abdominal region only (NOT intramuscular)
- Frequency: Once weekly (every 7 days)
- Available strengths: 50 mg, 75 mg, and 100 mg in pre-filled autoinjector 1
Dose Adjustment Protocol
Measure testosterone trough levels (drawn 7 days after the most recent dose) at 6 weeks, then adjust based on the following algorithm 1:
- If trough <350 ng/dL: Increase dose by 25 mg
- If trough 350-650 ng/dL: Maintain current dose
- If trough ≥650 ng/dL: Decrease dose by 25 mg
Continue dose adjustments every 6 weeks after changes until stable levels are achieved. The target trough concentration of 350-650 ng/dL provides testosterone exposures in the normal range throughout the entire weekly dosing interval 1.
Clinical Context: Why Xyosted Differs from Traditional Injectable Testosterone
Xyosted represents a fundamentally different approach compared to traditional intramuscular testosterone enanthate. While older guidelines recommend 75-100 mg IM weekly or 150-200 mg IM every 2 weeks for testosterone enanthate/cypionate 2, Xyosted's subcutaneous route and weekly dosing produces more stable testosterone levels with smaller peak-trough fluctuations 3, 4.
In the pivotal trial, 92.7% of patients achieved average total testosterone concentrations of 300-1,100 ng/dL at week 12, with mean levels of 553 ng/dL and a trough of 487 ng/dL at week 52 3. The pharmacokinetic profile shows a maximum concentration at approximately 12 hours post-injection, then slow decline over the week—creating steady-state levels by week 6 1, 3.
Key Advantages and Monitoring
The subcutaneous autoinjector was virtually painless (>95% reported no injection pain) and well-tolerated 3. This contrasts with traditional IM injections that produce more pronounced peak-trough variations and may be associated with mood/libido fluctuations 2, 5.
Monitoring Schedule:
- Testosterone levels: At 6 weeks, after each dose adjustment, then periodically 1
- Hematocrit: Baseline, 3 months, then every 3 months while on therapy 1
- PSA and digital rectal exam: Baseline, 3-6 months, then per age-appropriate screening 5
Common Pitfalls to Avoid:
- Do NOT administer intramuscularly—Xyosted is specifically formulated for subcutaneous use only 1
- Do NOT measure testosterone at random times—trough levels must be drawn exactly 7 days after the last injection for proper dose adjustment 1
- Do NOT skip the 6-week assessment—this is when steady-state is achieved and dose optimization should occur 1, 3
- Stop therapy if hematocrit >54% until it decreases to safe levels 1
The weekly subcutaneous dosing with Xyosted provides a more physiologic testosterone replacement pattern compared to every-2-week IM dosing, which can produce supraphysiological peaks and subtherapeutic troughs 6, 7.