From the Guidelines
Administration of Conjugated Estrogens (Premarin)
Conjugated estrogens, such as Premarin, are not always administered orally.
- The medication is available in various formulations, including oral tablets with doses ranging from 0.3 to 1.25 mg 1,
- vaginal cream, typically administered in a dose of 0.5 to 2 grams,
- and a topical emulsion formulation, Premarin Vaginal, for localized treatment of vaginal atrophy. The choice of administration route may depend on several factors, including patient preference, specific treatment goals, and potential side effects or risks associated with different routes of administration, such as the risk of venous thromboembolism which is increased with oral estrogen compared to transdermal or transvaginal routes 1. In clinical practice, the decision to use a particular formulation and route of administration should be based on individual patient needs and circumstances, considering the benefits and risks of each option, as well as the patient's medical history and current health status 1.
From the FDA Drug Label
Estrogens used in therapy are well absorbed through the skin, mucous membranes, and gastrointestinal tract. When applied for a local action, absorption is usually sufficient to cause systemic effects When conjugated with aryl and alkyl groups for parenteral administration, the rate of absorption of oily preparations is slowed with a prolonged duration of action, such that a single intramuscular injection of estradiol valerate or estradiol cypionate is absorbed over several weeks. When given orally, naturally-occurring estrogens and their esters are extensively metabolized (first pass effect) and circulate primarily as estrone sulfate, with smaller amounts of other conjugated and unconjugated estrogenic species.
The answer is no, conjugated estrogens (Premarin) is not always administered orally, as it can be absorbed through the skin, mucous membranes, and gastrointestinal tract, and can also be given via parenteral administration 2.
From the Research
Administration of Conjugated Estrogens (Premarin)
- Conjugated estrogens (Premarin) are not always administered orally, as there are vaginal cream and tablet forms available for treatment of vaginal atrophy and other menopausal symptoms 3, 4, 5, 6, 7.
Vaginal Administration
- Vaginal cream and tablet forms of conjugated estrogens (Premarin) have been shown to be effective in relieving symptoms of vaginal atrophy, such as dryness, itching, and dyspareunia 3, 4, 5, 6, 7.
- Studies have compared the efficacy and safety of vaginal conjugated estrogens (Premarin) cream with other treatments, such as hyaluronic acid vaginal cream and 17β-estradiol vaginal tablets 3, 4.
Systemic Effects
- While conjugated estrogens (Premarin) vaginal cream is intended for local action, studies have shown that it can have systemic effects, including increases in serum estradiol and estrone levels 6.
- The systemic bioavailability of estradiol and estrone has been evaluated in postmenopausal women using mass spectrometry assays, which have shown that vaginal conjugated estrogens (Premarin) cream can cause an approximately fivefold increase in serum estradiol levels 6.