Comparison of Testosterone Cream and Injections

Introduction

• Patients often compare testosterone cream dosages to testosterone injections.
• Example: Using testosterone cream trans-crotally twice a day, 150 mg each time can total over a gram a week.

Pharmacokinetics

• Four Major Steps:
  1. Absorption: Taking medication into the body.
  2. Distribution: Systemic bloodstream flow.
  3. Metabolism: Usually in the liver; medication is broken down into active or non-active forms.
  4. Excretion: Often via kidneys.
• These steps are crucial to understanding pharmacology and how medications/nutrients work in the body.

Administration Forms

• Oral vs. Injectable:

  • Oral medication is rapid, goes through the GI tract and the first liver pass.
  • Most hormones do not survive the first liver pass.
  • C17 alpha-alkylated anabolic hormones resist liver breakdown but may cause hepatotoxicity.
  • Oral medication requires larger doses than injections.

• Vitamin C Example:

  • 5,000 mg orally (in 1g tablets split throughout the day)
  • Equivalent to 500 mg via injection.

Absorption and Dosage

• Injectables:
  • Fast-acting (especially IVs); used for quick needs like hypoglycemia.
• Transdermal Creams:
  • Very slow to absorb; medication absorption varies greatly.
  • Factors: Skin type, age, patient-specific conditions.
  • Older patients absorb less but excrete slower.
  • Children have different absorption/excretion rates due to underdeveloped organs.

Misconceptions

• Incorrect to assume the same dosage form across different administration methods and patients.
• Testosterone Cream Concentrations:
  • 10% = 100 mg/ml
  • 20% = 200 mg/ml
  • Example: 4 clicks (1 ml) of 20% cream = 200 mg, but only ~10% absorption.
  • Cream dosages should be daily, not equivalent to weekly injectable doses.

Conclusion

• Dosage comparisons between creams and injections are inappropriate; they are different forms of administration with different absorption and efficacy rates.