Objectives: The objectives of this study were to determine therapeutic
serum testosterone (T) levels/ranges and inter-individual variance in
women treated with subcutaneous T implants.
Study design: In study group 1, T levels were measured at two separate
time intervals in pre- and postmenopausal women treated with
subcutaneous T for symptoms of androgen deficiency: (i) four weeks after
pellet insertion, and (ii) when symptoms of androgen deficiency
returned.
In a separate pharmacokinetic study (study group 2), 12 previously
untreated postmenopausal women each received a 100 mg T implant. Serum T
levels were measured at baseline, 4 weeks and 16 weeks following T
pellet implantation.
In study ‘group’ 3, serial T levels were measured throughout a 26 h
period in a treated patient.
Results: In study group 1, serum T levels measured at ‘week 4’ (299.36
+/- 107.34 ng/dl, n = 154), and when symptoms returned (171.43 +/- 73.01
ng/dl, n = 261), were several-fold higher compared to levels of
endogenous T. There was significant inter-individual variance in T
levels at ‘week 4’ (CV 35.9%) and when symptoms returned (CV 42.6%).
Even with identical dosing (study group 2), there was significant
inter-individual variance in T levels at ‘week 4’ (CV 41.9%) and ‘week
16’ (CV 41.6%). In addition, there was significant intra-individual
circadian variation (CV 25%).
Conclusions: Pharmacologic dosing of subcutaneous T, as evidenced by
serum levels on therapy, is needed to produce a physiologic effect in
female patients. Safety, tolerability and clinical response should guide
therapy rather than a single T measurement, which is extremely variable
and inherently unreliable. (c) 2012 Elsevier Ireland Ltd. All rights
reserved
