EPIQ CHEWS: The Science Behind OnyxMD's Daily Tadalafil + Vardenafil Chewable

Most men know that PDE5 inhibitors work. What fewer men know is that how you take them — the dose, the form, the frequency, and what you stack with them — matters enormously. EPIQ CHEWS is built on a specific clinical philosophy: that daily, low-dose treatment with a complementary PDE5 pair, supported by nutrients that address root-cause hormonal gaps, produces meaningfully better outcomes than occasional high-dose pills.

Here's the science behind that claim, and why the formulation works the way it does.

What Is EPIQ CHEWS?

EPIQ CHEWS is a daily chewable tablet containing four active ingredients:

• Tadalafil 5mg — the same dose used in FDA-approved daily ED therapy
• Vardenafil 5mg — a second PDE5 inhibitor with a complementary pharmacological profile
• Vitamin D3 — a fat-soluble steroid hormone precursor with established links to erectile and vascular function
• Vitamin K2 (MK-7) — the cofactor that directs calcium into bone and away from arterial walls, supporting the vascular health that underlies erections

Unlike on-demand pills designed to be taken 30–60 minutes before sex, EPIQ CHEWS is designed to be taken every day. That distinction changes everything about how it works.

The Case for Daily Low-Dose Therapy

The on-demand model has served millions of men well. But it has limitations. You have to plan ahead. A 30–100mg dose produces a spike-and-crash pharmacokinetic curve. And it does nothing for the underlying vascular and hormonal dysfunction that causes most ED in the first place.

Daily low-dose tadalafil takes a different approach. At 5mg per day, tadalafil maintains a near-constant plasma concentration, keeping PDE5 activity continuously inhibited at a physiological level. Clinical studies suggest this sustained inhibition may do more than enable erections on demand — it may support endothelial repair and smooth muscle relaxation over time.

A 2024 review published in The American Journal of Medicine found that both tadalafil and sildenafil use in ED patients was associated with reduced cardiovascular disease risk, with tadalafil providing greater benefits — consistent with its longer half-life and continuous endothelial exposure.

The chewable format enhances bioavailability. Without a hard tablet coating to dissolve, absorption begins sublingually and buccally, producing faster tissue exposure at a lower administered dose. This is why 5mg in a chewable can produce equivalent or superior tissue-level outcomes compared to higher doses in tablet form for many men.

Why Two PDE5 Inhibitors?

This is the part of the formulation that raises the most questions — and it has the most interesting pharmacological answer.

Tadalafil and vardenafil both inhibit PDE5, but they are not identical. Vardenafil is approximately ten times more potent on a per-milligram basis and has a slightly different binding affinity profile. A comparative review published in PMC found that patients receiving tadalafil reported the highest patient satisfaction and therapeutic effectiveness among PDE5 inhibitors, while vardenafil delivered high efficacy particularly for men who had not responded optimally to other agents.

The clinical intuition behind combining them is selectivity diversity: no two men have exactly the same PDE5 isoform expression or vascular phenotype. A dual-agent approach at low doses covers a broader range of receptor binding profiles without escalating to the side-effect burden of high-dose monotherapy. At 5mg each, neither agent is at a dose that typically produces significant headache, flushing, or vision disturbance — the side effects that cause many men to discontinue treatment.

This is physician-supervised formulation, not a DIY combination. The doses in EPIQ CHEWS are calculated to work synergistically within a safety envelope that a licensed prescribing physician evaluates for each individual patient.

Vitamin D3 and Erectile Function: The Evidence Is Growing

The inclusion of Vitamin D3 in an ED formulation might seem surprising if you've only seen it marketed for bone health. The clinical picture is considerably more nuanced.

A 2025 systematic review published in MDPI's Journal of Clinical Medicine examined the association between vitamin D levels and erectile dysfunction across multiple studies. The review found consistent associations between vitamin D deficiency and ED risk, with evidence suggesting both direct endothelial pathways and indirect testosterone-mediated pathways.

The mechanism is physiologically coherent. Vitamin D receptors are expressed in vascular endothelial cells, smooth muscle cells, and Leydig cells (the testosterone-producing cells of the testes). Activation of these receptors supports nitric oxide synthesis — the same molecular pathway that PDE5 inhibitors enhance downstream. Simultaneously, adequate vitamin D levels are associated with higher total and free testosterone.

A study published in PMC measured sexual function before and after vitamin D replacement therapy in deficient men. After supplementation, researchers found that total and free testosterone increased, and erectile function improved — independent of any PDE5 inhibitor use.

Vitamin D deficiency is widespread. Estimates suggest 40–50% of adults in North America and Europe are deficient. For men on daily tadalafil therapy, correcting that deficiency is not a minor add-on — it addresses a meaningful biological gap that PDE5 inhibition alone cannot fix.

The Role of Vitamin K2

Vitamin K2 sits in the formulation as vitamin D3's indispensable cofactor. This pairing is well-established in bone metabolism research, but its relevance to vascular and sexual health is increasingly recognized.

Vitamin D3 increases the absorption of calcium from the gut. Without adequate K2 to activate the carboxylation of matrix Gla-protein (MGP) and osteocalcin, that calcium can deposit in arterial walls rather than bone — a process called vascular calcification. Arterial calcification in the penile vasculature is one of the most common anatomical findings in men with refractory ED.

K2 (specifically the MK-7 form) activates MGP, which functions as the body's primary inhibitor of vascular calcification. Research cited in Frontiers in Reproductive Health (2025) supports the idea that vitamin D's benefits in ED are not merely hormonal but vascular — and K2 is what keeps that vascular environment clean.

Taking D3 without K2 is increasingly seen as incomplete. EPIQ CHEWS includes both at clinically relevant doses.

Who Is EPIQ CHEWS For?

The daily chewable format is best suited for men who:

• Experience ED regularly enough that on-demand dosing feels reactive and limiting
• Want the spontaneity of not timing a pill to sexual activity
• Are concerned about cardiovascular health alongside sexual function
• Suspect their vitamin D levels may be suboptimal (extremely common)
• Have tried on-demand PDE5 inhibitors but experienced inconsistent results

It is not the right fit for men who prefer on-demand dosing for occasional use, or for men who need maximum-strength intervention for severe ED (for whom OnyxMD's Mach 1 formulation may be more appropriate).

How It Works in Practice

The daily chew is designed to be taken at the same time each day — most men take it in the morning with or without food. The chewable format means no water required. It dissolves within 30–60 seconds and is absorbed rapidly.

Within 7–14 days of consistent daily use, most men report that spontaneous erections become more reliable and their response during sexual activity feels less effortful. The cumulative vascular benefit of sustained PDE5 inhibition at the endothelial level takes several weeks to reach its full expression.

The nutrient components (D3 + K2) operate on a longer timeline. Vitamin D levels normalize over 4–8 weeks with consistent daily supplementation, and the vascular benefits of K2 accumulate gradually. This is a formulation designed for men who want to build toward sustained, long-term function — not just a temporary fix.

Physician Supervision: Why It Matters

EPIQ CHEWS is a prescription product. That's not a bureaucratic inconvenience — it's a meaningful safety feature. Tadalafil and vardenafil both interact with nitrate medications (used in cardiac conditions), and combining PDE5 inhibitors without a clinical review creates cardiovascular risk for specific patient populations.

OnyxMD's intake process is a free, physician-reviewed questionnaire that screens for these contraindications and determines whether EPIQ CHEWS is appropriate for each patient. It takes a few minutes and does not require an in-person visit.

The Formulation Philosophy

EPIQ CHEWS is designed around a principle that's increasingly well-supported in the ED treatment literature: the best outcomes come from sustained, multi-mechanism intervention rather than high-dose, single-mechanism episodic treatment.

PDE5 inhibition improves acute hemodynamics. Vitamin D and K2 address the hormonal and vascular substrate that determines how well PDE5 inhibition can work in the first place. The chewable format optimizes bioavailability. The daily cadence produces pharmacokinetic stability. Each element of the formulation serves a specific, evidence-supported purpose.

This isn't a supplement stack assembled from trending ingredients. It's a clinically reasoned formulation designed to address ED at multiple levels simultaneously — and it requires a physician's sign-off for exactly that reason.

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If you're ready to explore clinically-formulated options, OnyxMD offers physician-supervised treatment plans starting with a free online assessment at questionnaire.getonyxmd.com.

You can also explore the full EPIQ CHEWS product page or browse the OnyxMD blog for more on men's sexual health.

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These statements have not been evaluated by the FDA. This content is for informational purposes only and does not constitute medical advice.