Aminotadalafil
OtherPreclinicalAlso known as: Amino-Tadalafil
Aminotadalafil is an unapproved research analog of tadalafil, the PDE5 inhibitor marketed under the brand name Cialis for erectile dysfunction and under Adcirca for pulmonary arterial hypertension. Structurally, aminotadalafil differs from tadalafil by the presence of an amino substituent on the tadalafil scaffold — most commonly the methylenedioxyphenyl ring has been modified with an amino group in place of one of the ring features.
Overview
At A Glance
Aminotadalafil's mechanism is presumed to be substantially identical to tadalafil — selective inhibition of the type 5 phosphodiesterase enzyme (PDE5) — but with inferior and less well-characterized potency, selectivity, and pharmacokinetics. To understand aminotadalafil, start w…
Mechanism of Action
Aminotadalafil's mechanism is presumed to be substantially identical to tadalafil — selective inhibition of the type 5 phosphodiesterase enzyme (PDE5) — but with inferior and less well-characterized potency, selectivity, and pharmacokinetics. To understand aminotadalafil, start with the parent compound:
PDE5 inhibition (the core mechanism):
- Nitric oxide (NO) released from vascular endothelium and nerve terminals activates guanylate cyclase in smooth muscle cells.
- Guanylate cyclase converts GTP to cGMP.
- cGMP triggers smooth muscle relaxation in the corpus cavernosum, pulmonary vasculature, and other vascular beds.
- PDE5 is the enzyme that degrades cGMP back to GMP, terminating the signal.
- Inhibiting PDE5 prolongs the cGMP signal, sustaining smooth muscle relaxation and vasodilation.
In the erectile context, this allows a man with intact parasympathetic nerve function and adequate NO signaling to achieve and maintain an erection in response to sexual stimulation. In the pulmonary hypertension context, it reduces pulmonary vascular resistance and improves exercise tolerance.
Why the amino modification matters: The exact pharmacologic consequences of the amino substitution on the tadalafil scaffold depend on where the amino group sits. Published analytical characterization work, including Reepmeyer and d'Avignon (2008) and Venhuis et al. (2010), documented aminotadalafil's structure and confirmed that it retains PDE5-inhibitory activity in vitro, albeit at different potency from tadalafil. The substitution is theorized to:
- Potentially extend the half-life through altered metabolic pathways (amino groups can affect CYP-mediated clearance)
- Slightly alter receptor-binding profile, possibly compromising the high PDE5-versus-PDE6 selectivity that makes tadalafil comparatively free of visual side effects
- Change aqueous solubility and oral bioavailability in ways that have not been well studied in humans
What we do not know:
- Whether aminotadalafil produces the same clinical profile as tadalafil at equivalent doses
- The precise half-life in humans (tadalafil is ~17.5 hours; aminotadalafil's human PK has not been cleanly published)
- Whether it shares tadalafil's relatively favorable PDE6 selectivity (relevant to visual side effects) or more closely resembles the less-selective sildenafil in that regard
- Long-term safety, given there have been no long-term dosing studies in humans
The practical summary is that aminotadalafil behaves enough like tadalafil to "work" (produce erectile effects in users), but without the decades of pharmacologic characterization, manufacturing quality control, and post-market safety surveillance that come with approved tadalafil. Every uncertainty is resolved in favor of "use the approved drug."
Overview
Aminotadalafil is an unapproved research analog of tadalafil, the PDE5 inhibitor marketed under the brand name Cialis for erectile dysfunction and under Adcirca for pulmonary arterial hypertension. Structurally, aminotadalafil differs from tadalafil by the presence of an amino substituent on the tadalafil scaffold — most commonly the methylenedioxyphenyl ring has been modified with an amino group in place of one of the ring features. The modification was originally created in medicinal chemistry labs as part of structure–activity-relationship explorations around the tadalafil core, but unlike tadalafil itself, aminotadalafil never progressed through clinical development and has never been approved by any regulatory authority in any jurisdiction.
The reason this compound has its own compound page is not that it is a superior or interesting drug — it is almost certainly inferior to the approved tadalafil — but that aminotadalafil has been detected repeatedly as an illegal adulterant in so-called "natural" or "herbal" male-enhancement supplements sold online and in gas stations and convenience stores, primarily in the United States, Europe, and Southeast Asia. The FDA, the Dutch RIVM, and other regulatory agencies have issued dozens of warnings and seizure notices targeting products found to contain aminotadalafil (and its cousins acetildenafil, homosildenafil, thiomethisosildenafil, and others) alongside nominally "all natural" herbal ingredients. For readers encountering aminotadalafil in a supplement label, on a bodybuilding or biohacking forum, or in a bulk-research-chemical catalog, this page summarizes what the compound actually is, what is known about its pharmacology, and why it is a legal and medical minefield.
This entry takes the position that aminotadalafil is a research chemical with inferior characterization and no meaningful advantage over the prescription-available tadalafil, that it is routinely encountered as an adulterant rather than as an intentional product, and that readers should overwhelmingly prefer the licensed generic tadalafil prescribed through a legitimate medical channel. For PDE5 inhibitor content written from a legitimate-pharmacy perspective, see tadalafil (if available in our catalog) and related vascular and metabolic tuning entries in the erectile dysfunction and vascular health section. For context on other gray-market adulterant-prone compounds, see RU-58841.
Chemical Information
IUPAC Name
(6R,12aR)-6-(aminomethyl)-2-methyl-2,3,6,7,12,12a-hexahydro-pyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione
CAS Number
38580-07-3
Molecular Formula
C21H18N4O4
Molecular Mass
390.40 g/mol
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Interactions
Interaction Matrix
Contraindications
Absolute contraindications to aminotadalafil (and all PDE5 inhibitors):
- Concurrent nitrate therapy — nitroglycerin, isosorbide mononitrate, isosorbide dinitrate, amyl nitrite, or any nitrate donor. The combination can cause life-threatening hypotension.
- Recent myocardial infarction (within 90 days) or unstable angina
- Severe heart failure (NYHA class III–IV)
- Severe hypotension (systolic BP below 90 mmHg) or uncontrolled hypertension (systolic BP above 170 mmHg)
- Recent stroke (within 6 months)
- History of non-arteritic anterior ischemic optic neuropathy (NAION) — PDE5i use is associated with recurrence
- Severe hepatic impairment (Child-Pugh C)
- Retinitis pigmentosa
- Known hypersensitivity to tadalafil or related compounds
- Use with guanylate cyclase stimulators (riociguat) — pulmonary hypertension drug; combination causes severe hypotension
- Pediatric use — not appropriate
Absolute contraindication specific to aminotadalafil (beyond the class):
- Any situation in which regulatory oversight, manufacturing quality, and dose accuracy matter. This effectively means aminotadalafil should not be used in any legitimate medical scenario.
Relative contraindications requiring medical oversight:
- Concurrent alpha-blocker therapy for BPH or hypertension (tamsulosin, doxazosin, etc.) — dose separation required
- Strong CYP3A4 inhibitor use (ritonavir, ketoconazole, itraconazole, clarithromycin, certain HIV antivirals) — dose reduction required
- Moderate hepatic or renal impairment — dose adjustment required
- Anatomic deformities of the penis (Peyronie's disease, severe fibrosis) — increased priapism risk
- Sickle cell disease, multiple myeloma, leukemia — increased priapism risk
- Bleeding diatheses or active peptic ulcer — PDE5i can increase bleeding risk
- Concurrent alcohol use in large amounts
- History of NAION in one eye — at high risk of the other eye
- Men using concurrent SSRIs for premature ejaculation — usually manageable but monitor for cumulative sexual dysfunction
Drug interactions:
- Nitrates — absolute contraindication
- Guanylate cyclase stimulators (riociguat) — absolute contraindication
- Alpha-blockers — dose separation and caution
- CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin, grapefruit juice in very large quantities) — dose reduction
- CYP3A4 inducers (rifampin, phenytoin, carbamazepine, St. John's wort) — reduced PDE5i efficacy
- Antihypertensive agents (ACE inhibitors, ARBs, calcium channel blockers, beta-blockers, diuretics) — additive hypotension, generally manageable with routine monitoring
- Other PDE5 inhibitors — do not combine
Populations requiring specialist evaluation before any PDE5i use:
- Men with known cardiovascular disease, including CAD and heart failure
- Men with pulmonary arterial hypertension (specialist-managed)
- Men on complex antihypertensive regimens
- Men with hepatic or renal impairment
- Men with a history of priapism from any cause
- Transplant recipients on CYP3A4-affecting immunosuppressants
- Older men with multiple comorbidities
Baseline evaluation before beginning any PDE5i therapy:
- Full cardiovascular history and examination
- Blood pressure at rest and with positional change
- Current medication review, especially for nitrates and alpha-blockers
- Review of visual and auditory history
- Lipid profile, fasting glucose, A1c, basic metabolic panel
- Testosterone (total and free) — hypogonadism frequently co-occurs with ED
- Review of psychological and relationship factors
Monitoring during PDE5i therapy:
- Response — erectile function improvement, side effects
- Blood pressure if on antihypertensives or alpha-blockers
- New vision or hearing symptoms — stop immediately if they occur
- New chest pain or exercise intolerance — stop and evaluate
- Annual cardiovascular risk reassessment
The bottom line on contraindications: treat aminotadalafil's contraindication list as at least as strict as tadalafil's, with an additional implicit contraindication for the compound being an unapproved, unregulated, adulterated-supplement-associated material. For any reader with a legitimate medical indication, use prescription tadalafil from a legitimate prescriber and abandon aminotadalafil entirely.
Research Disclaimer
This interaction data is compiled from published research and community reports. It may not be exhaustive. Always consult a healthcare professional before combining compounds.
$54.00
$1.8000
1
1
liquid
| Vendor | Product | Form | Qty | Price | $/mg | Coupon | |
|---|---|---|---|---|---|---|---|
 |
Amino Tadalafil Oral Liquid | liquid | 1 bottle● In Stock | $54.00BEST | $1.800 |
Tracking since Apr 3, 2026 · 1 data point
Vendors Selling Aminotadalafil
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Related Compounds
View AllB7-33
OtherPreclinicalB7-33 is a single-chain, 26-amino-acid peptide engineered as a functionally selective agonist of the relaxin family peptide receptor 1 (RXFP1), designed to recapitulate the therapeutic activity of human H2 relaxin — the endogenous peptide hormone that is naturally elevated during pregnancy and has broad cardioprotective, vasodilatory, and anti-fibrotic effects.
KSPTN
OtherPreclinicalKSPTN is a novel research peptide available from select peptide research vendors.
Melanotan I
OtherFDA ApprovedMelanotan I (afamelanotide) is a linear synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH) with the substitution of norleucine at position 4 and D-phenylalanine at position 7.
PNC-27
OtherPreclinicalPNC-27 is a p53-derived peptide that selectively induces membranolysis in cancer cells.
Prostamax
OtherPreclinicalProstamax is a short synthetic peptide developed in Russia by Vladimir Khavinson and collaborators at the St.
RU-58841
OtherPreclinicalRU-58841 (also known as PSK-3841 or HMR-3841, and commonly written simply as RU in hair-loss forums) is a non-steroidal androgen receptor antagonist originally developed by Roussel Uclaf (later absorbed into Sanofi) in the late 1980s and early 1990s.
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Protocols, calculator & safety for Aminotadalafil
Research Score
9 PubMed studies
Quality Indicators
Data Completeness
100%Research Credibility
Limited research available
Quick Facts
Molecular Weight
390.40 g/mol
CAS Number
38580-07-3
Trial Phase
Preclinical
Research Disclaimer
This information is for educational and research purposes only. Not intended as medical advice. Consult a healthcare professional before use.
Frequently Asked Questions
Is aminotadalafil the same as tadalafil (Cialis)?
No. Aminotadalafil is a structural analog of tadalafil with an amino group substitution on the tadalafil scaffold. It has never been approved by any regulatory authority, has no legitimate manufacturing standard, and is most frequently encountered as an illegal adulterant in supplements marketed as 'natural male enhancement.' Tadalafil is the FDA-approved drug sold as Cialis and Adcirca, with decades of clinical data and low-cost generic availability. If a PDE5 inhibitor is medically indicated, prescription tadalafil is the correct choice — not aminotadalafil.
Why does aminotadalafil exist if tadalafil already exists?
Aminotadalafil was originally synthesized in medicinal chemistry structure–activity-relationship work around the tadalafil core. Its modern presence in the consumer market is not as a developed drug but as an adulterant in counterfeit or 'herbal' supplements. The amino modification is sometimes speculated to extend the compound's shelf life, alter its detection profile in routine drug testing, or avoid patent infringement on tadalafil — none of which are legitimate medical or regulatory reasons to prefer it over the approved drug.
Is it legal to buy aminotadalafil?
In most jurisdictions, aminotadalafil is not scheduled as a controlled substance, but it is also not approved for sale as a human drug or supplement. Selling it as a dietary supplement is illegal in the United States (the FDA treats PDE5i analogs in supplements as unapproved drugs and has conducted extensive enforcement). Purchasing it as a 'research chemical' sits in a gray area that varies by country, but importation and consumption remain legally and medically risky. Tested athletes should note that PDE5 inhibitors are not on the WADA prohibited list, but purity and contamination in gray-market sources can cause inadvertent positive tests for other substances.
How does aminotadalafil compare to sildenafil (Viagra)?
Aminotadalafil most closely resembles tadalafil (Cialis) rather than sildenafil (Viagra). The two approved drugs differ in half-life — sildenafil's effect is shorter (4–6 hours) while tadalafil's effect is longer (up to 36 hours) — and in food and visual side-effect profiles. Aminotadalafil presumably shares tadalafil's long half-life, but this has not been cleanly characterized in humans. In practice, the comparison is moot: both tadalafil and sildenafil are approved, generic, inexpensive, and available by prescription. Aminotadalafil is not a legitimate choice in that competitive landscape.
Can aminotadalafil show up in a drug test?
Routine workplace or legal drug panels do not test for PDE5 inhibitors. Specialized anti-doping panels also do not include PDE5 inhibitors, as they are not WADA prohibited. However, forensic testing in a medical adverse event investigation or criminal investigation can identify aminotadalafil specifically, and regulatory labs identify it routinely in seized supplements. The bigger testing concern for users is that gray-market aminotadalafil-containing products often also contain other adulterants, some of which can cause unexpected positive tests for controlled substances.
What happens if I took a 'natural' supplement and it turns out it contained aminotadalafil?
This is a common scenario and is the primary real-world exposure pathway for aminotadalafil. Steps to take: first, stop the supplement immediately. Second, check the FDA's Tainted Sexual Enhancement Products database to see if the specific product has been recalled. Third, if you experienced any adverse effects — headache, flushing, dizziness, chest symptoms, priapism, visual changes — see a clinician and mention the supplement exposure specifically. Fourth, if you are also taking nitrates, alpha-blockers, or other cardiovascular medications, flag this as a critical interaction concern with your prescriber. Report the product to the FDA's MedWatch system to help prevent exposure in other consumers.
Is there any legitimate reason to use aminotadalafil over prescription tadalafil?
Practically, no. Prescription tadalafil is inexpensive (often under $1 per dose generic), readily available through primary care and telehealth services, manufactured to pharmaceutical quality standards, and backed by decades of safety data. Aminotadalafil offers no documented clinical advantage and carries the full risk profile of a research chemical — unknown purity, dose variability, no regulatory oversight, frequent contamination. The only 'reason' aminotadalafil appears in consumer products is to allow unscrupulous supplement makers to sell a PDE5 effect while formally claiming their product is 'natural' and 'drug-free.'
Does aminotadalafil have the same side effects as tadalafil?
Best available evidence, from case reports and pharmacologic inference, suggests yes — headache, flushing, back pain, dyspepsia, nasal congestion, and rare but serious events like priapism, NAION, and sudden hearing loss are all expected. Additional concerns with aminotadalafil include unknown selectivity profile (visual and muscle side effects may be worse than tadalafil), dose inconsistency from gray-market supply, and contamination from adulterant manufacturing. The class-level interaction with nitrates is preserved and remains the single most dangerous combination.
Can I use aminotadalafil for performance in endurance sport?
There is no meaningful evidence base for PDE5 inhibitors as legitimate endurance aids in healthy athletes. PDE5i use in high-altitude medicine for HAPE prophylaxis is a specific clinical indication, not a performance-enhancement pathway. Tadalafil and sildenafil are not on the WADA prohibited list, so their use in tested sport is not formally banned, but using aminotadalafil instead of a legitimate PDE5 inhibitor creates risk of contamination-driven positive tests for other substances. For legitimate altitude performance support, consult a high-altitude medicine specialist and use prescription tadalafil.
What should I actually do if I have erectile dysfunction?
See a clinician for a proper evaluation — in-person or through a legitimate telehealth platform. ED is frequently an early marker of cardiovascular disease, diabetes, or hypogonadism, all of which deserve assessment and treatment on their own merits. Baseline labs typically include fasting glucose, A1c, lipid panel, testosterone, thyroid, and CBC/CMP. Lifestyle interventions — weight management, cardiovascular exercise, smoking cessation, sleep and alcohol moderation — produce durable improvements. If a PDE5 inhibitor is indicated, generic tadalafil 10 mg as-needed or 5 mg daily is a common and effective starting point, and the cost is minimal through insurance or legitimate cash-pay telehealth. Do not source PDE5 inhibitors from 'natural' supplements or bulk research chemicals. The prescription pathway is cheaper, safer, and more effective. For a broader view of vascular and metabolic optimization that supports sexual health, see /stack and related compound entries.
Research Tools
Related Compounds
View AllB7-33
OtherPreclinicalB7-33 is a single-chain, 26-amino-acid peptide engineered as a functionally selective agonist of the relaxin family peptide receptor 1 (RXFP1), designed to recapitulate the therapeutic activity of human H2 relaxin — the endogenous peptide hormone that is naturally elevated during pregnancy and has broad cardioprotective, vasodilatory, and anti-fibrotic effects.
KSPTN
OtherPreclinicalKSPTN is a novel research peptide available from select peptide research vendors.
Melanotan I
OtherFDA ApprovedMelanotan I (afamelanotide) is a linear synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH) with the substitution of norleucine at position 4 and D-phenylalanine at position 7.
PNC-27
OtherPreclinicalPNC-27 is a p53-derived peptide that selectively induces membranolysis in cancer cells.
Prostamax
OtherPreclinicalProstamax is a short synthetic peptide developed in Russia by Vladimir Khavinson and collaborators at the St.
RU-58841
OtherPreclinicalRU-58841 (also known as PSK-3841 or HMR-3841, and commonly written simply as RU in hair-loss forums) is a non-steroidal androgen receptor antagonist originally developed by Roussel Uclaf (later absorbed into Sanofi) in the late 1980s and early 1990s.
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