What is the recommended protocol for testosterone therapy via injection?

Recommended Protocol for Testosterone Injection Therapy

For testosterone replacement therapy via injection, the recommended protocol is to administer testosterone cypionate or enanthate at 50-200 mg intramuscularly every 2 weeks, or 50 mg weekly, with injections given deep in the gluteal muscle. 1, 2

Diagnostic Criteria Before Initiating Therapy

• Confirm testosterone deficiency with:
  • Morning total testosterone levels <300 ng/dL on at least two separate occasions 3
  • Presence of symptoms (decreased energy, libido, muscle mass, body hair, hot flashes, gynecomastia, infertility) 2
  • Free testosterone by equilibrium dialysis should be frankly low on at least 2 separate assessments 2

Injection Protocol Details

Medication Options

• Testosterone cypionate (100 mg/mL or 200 mg/mL) 1
• Testosterone enanthate (200 mg/mL) 4
• Testosterone undecanoate (250 mg/mL): 750 mg initially, followed by 750 mg after 4 weeks, then 750 mg every 10 weeks 3

Administration Technique

• Intramuscular injection only (never intravenous) 1
• Injection site: Deep in the gluteal muscle 1
• Self-injection: Thigh is recommended site 2
• When administered by another person: Gluteal administration 2

Dosing Schedule

• Standard dosing: 100-200 mg every 2 weeks or 50 mg weekly 2, 1
• Dosage range for hypogonadal males: 50-400 mg every 2-4 weeks 1
• Target mid-normal testosterone level: 450-600 ng/dL 2, 3

Monitoring Protocol

Initial Monitoring (3-6 months)

• Testosterone levels: Measure midway between injections, targeting 500-600 ng/dL 2, 3
• Hematocrit: Discontinue if exceeds 54% 3
• PSA: Biopsy if >4.0 ng/mL or increases >1.0 ng/mL/year 3
• Symptom response evaluation 3

Long-term Monitoring (every 6-12 months)

• Testosterone levels 2, 3
• Hematocrit 3
• PSA (in men ≥40 years) 3
• Symptom evaluation 3

Advantages and Disadvantages of Injectable Testosterone

Advantages

• Relatively inexpensive compared to other formulations 2
• Flexible/infrequent dosing 2
• No risk of transference to others 2
• Higher patient compliance due to less frequent administration 2

Disadvantages

• Requires intramuscular injection 2
• Fluctuating serum testosterone levels with peaks and valleys 2
• Potentially greater risk of cardiovascular events compared to gels 2
• Time spent in both supratherapeutic and subtherapeutic ranges between injections 2

Important Considerations and Precautions

• Contraindications: Breast or prostate cancer, hematocrit >50%, severe untreated sleep apnea, severe lower urinary tract symptoms, uncontrolled heart failure 3
• Not recommended for men with desire for current or future fertility 3
• Discontinue if no improvement in sexual function within 12 months 3
• Consider therapeutic phlebotomy for rapid correction of elevated hematocrit levels 3
• Inspect solution visually for particulate matter before administration 1
• Warming and shaking the vial should redissolve any crystals that may have formed during storage 1

Alternative Formulations to Consider

If injections are not suitable, consider:

• Transdermal gels (1-1.62%): 50-100 mg/day applied to skin of back, abdomen, upper thighs, and upper arms 2
• Transdermal patches: 2-6 mg/day applied to dry, intact skin 2
• Subcutaneous implants (pellets): 150-450 mg every 3-6 months 2

Injectable testosterone remains a common and effective method for testosterone replacement therapy, particularly when cost and convenience are important considerations, despite potential fluctuations in hormone levels between doses.