For prescribers managing menopausal and perimenopausal hormone therapy, Bi-Est (estradiol + estriol) is a cornerstone formulation. Mixwell Compounding Pharmacy in Chino, CA prepares custom Bi-Est transdermal cream to your exact prescribed ratio and strength — formulated in advanced PCCA permeation-enhancing bases built for absorption, stability, and an elegant patient experience.
🌸 What Is Bi-Est?
Bi-Est is a compounded combination of two bioidentical estrogens — estradiol (E2) and estriol (E3). Estriol typically makes up the larger share of the formulation, while estradiol accounts for most of the estrogenic activity. Prescribers select the ratio — commonly 80:20 or 50:50 (E3:E2) — based on each patient's hormone levels, symptoms, and clinical goals.
Bi-Est is frequently prescribed alongside progesterone, testosterone, or DHEA as part of a full-spectrum hormone strategy. Mixwell compounds to your exact specifications.
💧 Why Prescribers Prefer the Transdermal Route
Bi-Est is generally available in oral, transdermal, and vaginal preparations — and the transdermal route is a frequent prescriber preference.
Transdermal
★ Frequent preferenceBypasses first-pass hepatic metabolism; estrogens are fat-soluble and absorb well through skin.
Oral
A familiar route; subject to first-pass liver metabolism.
Vaginal
Useful for localized symptoms per prescriber direction.
Because estradiol and estriol are fat-soluble, the transdermal route allows efficient skin absorption while avoiding the first-pass hepatic effect associated with oral administration. The prescriber determines the most appropriate route for each patient.
🧪 Advanced PCCA Permeation-Enhancing Bases
For transdermal hormone therapy, the base is critical — it governs how well the actives move through the skin and how stable and elegant the finished preparation is. Mixwell formulates Bi-Est transdermal creams in PCCA's industry-recognized permeation-enhancing bases.
💎 Lipoderm® — The Transdermal Standard
PCCA's flagship permeation-enhancing base for transdermal delivery.
🎯 Proven permeation
A widely used, well-studied transdermal base designed to deliver actives — including hormones — through the skin.
🧬 Multi-hormone capable
Accommodates combination hormone formulations, supporting Bi-Est alongside progesterone or testosterone as prescribed.
✨ Elegant feel
A smooth, cosmetically refined application patients are more likely to use consistently.
📊 Research-backed
Featured in peer-reviewed percutaneous-absorption research on compounded estrogen formulations.
🌿 PermE8™ — Anhydrous Permeation Enhancement
For enhanced permeation with extended stability.
💧 Anhydrous stability
Water activity below 0.6 supports prolonged default beyond-use dates without costly stability testing.
🧬 Multi-active capable
Holds multiple actives at once, including salt forms and ingredients unstable in water.
🔁 Fewer refills
Longer default BUDs can mean less-frequent refills and added patient convenience.
✨ Silky finish
A smooth, non-tacky, non-oily texture for comfortable daily application.
❓ What is a permeation-enhancing base?
A permeation-enhancing base is a specialized transdermal vehicle designed to help active ingredients cross the skin barrier and reach systemic circulation. For transdermal hormone therapy like Bi-Est, these bases support consistent delivery of fat-soluble estrogens through the skin while providing a stable, cosmetically elegant finished preparation.
⭐ Why Prescribers & Patients Choose Compounded Bi-Est
🩺 For Prescribers
- Specify the exact E3:E2 ratio and total strength your patient needs
- Combine with progesterone, testosterone, or DHEA in one preparation
- Choose a research-backed transdermal or anhydrous base
- Request dye-, paraben-, or fragrance-free formulations
🌸 For Patients
- A single elegant cream rather than multiple products
- Smooth, non-greasy feel for easy daily application
- Transdermal route avoids the first-pass liver effect of oral forms
- Custom-tailored to the prescriber's plan
📚 The Evidence Base
A 2025 in vitro percutaneous-absorption study published in Pharmaceutics evaluated compounded estradiol and Bi-Est (E3/E2) formulations in proprietary permeation-enhancing bases compared with a commercially available estradiol transdermal gel — examining how base selection influences transdermal estrogen delivery. Foundational pharmacology literature notes that Bi-Est is composed primarily of estriol, while estradiol accounts for most of its estrogenic activity, and that Bi-Est is available in oral, transdermal, and vaginal preparations.
Transdermal estrogen delivery bypasses first-pass hepatic metabolism. The prescriber determines whether Bi-Est, the route, and the formulation are appropriate for each patient based on individual evaluation.
🚀 How to Send a Prescription
- Specify the E3:E2 ratio, total strength, base (Lipoderm® or PermE8™), and any combination hormones on your prescription.
- Fax or e-prescribe to Mixwell Compounding Pharmacy in Chino, CA.
- Call (909) 378-7301 to confirm the formulation, dispensing device, and current turnaround time.
- Your patient picks up at our Chino pharmacy or asks about delivery options.
📍 Serving Women's-Health Practices Across Southern California
❓ Frequently Asked Questions
What ratios of Bi-Est can Mixwell compound?
We compound to your prescribed E3:E2 ratio and total strength. Common prescriber-selected ratios include 80:20 and 50:50, but we prepare whatever your prescription specifies.
Why is Lipoderm® a preferred base for transdermal Bi-Est?
Lipoderm® is PCCA's flagship permeation-enhancing transdermal base, widely used and studied for delivering actives — including hormones — through the skin, while providing a smooth, cosmetically elegant finish that supports consistent patient use.
What makes PermE8™ different from Lipoderm®?
PermE8™ is an anhydrous permeation-enhancing base with water activity below 0.6. Its low water activity supports prolonged default beyond-use dates and accommodates actives that are unstable in water, while also enhancing permeation.
Can Bi-Est be combined with progesterone or testosterone?
Yes. Bi-Est is frequently compounded alongside progesterone, testosterone, or DHEA in a single preparation, as specified by the prescriber.
Is a prescription required?
Yes. Compounded Bi-Est is prepared only pursuant to a valid prescription from a licensed prescriber.
Does Mixwell accept insurance?
Mixwell does not accept insurance. Call (909) 378-7301 for current pricing.
Can I use my HSA or FSA to pay for compounded medications?
Yes, you should be able to charge your compounded medications to your HSA or FSA account; however, we cannot charge veterinary prescriptions to these accounts. Call (909) 378-7301 for pricing.
Partner With Mixwell for Custom Bi-Est Formulations
Mixwell Compounding Pharmacy
13788 Roswell Ave, Ste 158 · Chino, CA 91710
PCCA Member · CA Licensed · USP <795> · Non-Sterile Compounding
📞 Call (909) 378-7301References: In Vitro Percutaneous Absorption of Permeation-Enhancing Estrogen Formulations. Pharmaceutics. 2025. PMC12030386. | Files JA, Ko MG, Pruthi S. Bioidentical Hormone Therapy. Mayo Clin Proc / PMC3127562. | Bi-Est available in oral, transdermal, and vaginal preparations per published bioidentical hormone therapy literature. | Lipoderm® and PermE8™ are permeation-enhancing compounding bases from PCCA; base characteristics per manufacturer technical documentation. | Educational information for licensed prescribers; not a substitute for clinical judgment. Reviewed by Mixwell Compounding Pharmacy compounding team, Chino, CA.