From the Research
Pharmacological Equivalence of Estrogen Patches
The question of whether two 0.25 mg estrogen patches are pharmacologically equivalent to one 0.5 mg estrogen patch can be examined by looking at the available evidence on the efficacy and safety of different doses of estrogen patches.
- The study by 1 compared the efficacy of three doses of estradiol gel (0.1% Divigel) in reducing vasomotor symptoms in postmenopausal women. The results showed that all three doses (1.0.5, and 0.25 mg/day) were effective in reducing the frequency and severity of hot flushes, but the study did not directly compare the pharmacological equivalence of different patch doses.
- The study by 2 evaluated the efficacy and safety of a seven-day, transdermal estradiol system in healthy postmenopausal women with hot flushes. The study compared two doses of estradiol patches (0.05 mg/day and 0.1 mg/day) with a placebo patch, but did not provide information on the pharmacological equivalence of two 0.25 mg patches versus one 0.5 mg patch.
- The studies by 3, 4, and 5 also did not directly address the question of pharmacological equivalence between two 0.25 mg estrogen patches and one 0.5 mg estrogen patch.
Key Findings
- The available evidence suggests that different doses of estrogen patches can be effective in reducing vasomotor symptoms in postmenopausal women, but the studies do not provide a direct comparison of the pharmacological equivalence of two 0.25 mg patches versus one 0.5 mg patch.
- The study by 1 showed that a low-dose transdermal estradiol gel (0.25 mg estradiol, delivering 0.003 mg/d estradiol) was effective in treating vasomotor symptoms, but it is unclear whether this dose is pharmacologically equivalent to a 0.5 mg estrogen patch.
- Further studies are needed to determine the pharmacological equivalence of different estrogen patch doses.