Section 1 of 9Overview
Overview
PF-06260414 (also written PF 06260414 or PF06260414) is a nonsteroidal selective androgen receptor modulator (SARM) — a small synthetic molecule built on a thiadiazinane-substituted isoquinoline-carbonitrile scaffold (C14H14N4O2S). It is NOT a peptide and NOT a steroid — it is a designed small-molecule drug intended to activate the androgen receptor in a tissue-selective way.
PF-06260414 was developed by Pfizer. Its entire public human record is a single completed Phase 1 first-in-human study in healthy adult men (NCT02070939; Bhattacharya et al., Clinical Therapeutics 2016, PMID 27085586). There is no public evidence that it advanced beyond Phase 1, and its intended clinical indication was never publicly finalized. It appears on this peptide reference because it is discussed, sold, and stacked alongside peptides in the "research chemical" community — not because it is one.
Not approved — investigational, with androgen-suppression and a liver-enzyme signal
PF-06260414 is not approved by any regulator (FDA, EMA, or otherwise) for any use, including muscle growth, physique, or performance. Its only human exposure is a single, short Phase 1 study. In that study it was generally well tolerated with no serious adverse events, but elevated ALT (a liver enzyme) was the most frequent adverse event, and it dose-dependently suppressed total testosterone, SHBG, and HDL cholesterol — a signature consistent with on-target androgen activity that also implies HPTA (natural testosterone) suppression. No long-term human safety data exist. As a SARM it is WADA-prohibited at all times. This page is educational and is not medical, legal, or dosing advice; nothing here endorses or guides human use. This is not a "milder, safer, or legal alternative" to anabolic steroids. Dated 2026-07-10.
Section 2 of 9Chemistry and structure
Chemistry and structure
PF-06260414 is a small-molecule isoquinoline-carbonitrile bearing a cyclic sulfamide (thiadiazinane 1,1-dioxide) — an amino-acid chain it is not.
| Property | Value |
|---|---|
| Name | PF-06260414 (6-[(4R)-4-methyl-1,1-dioxo-1,2,6-thiadiazinan-2-yl]isoquinoline-1-carbonitrile) |
| Class | Nonsteroidal selective androgen receptor modulator (SARM) — not a peptide, not a steroid |
| Molecular formula | C14H14N4O2S |
| Molecular weight | 302.35 g/mol (PubChem CID 76071881) |
| CAS number | 1612755-71-1 |
| Developer | Pfizer |
| Route | Orally active |
| Elimination half-life | ~6.9–12.8 h (oral, healthy adult men; PMID 27085586) |
Section 3 of 9Mechanism of action
Mechanism of action
- Androgen receptor (AR) modulation [Human]. PF-06260414 acts as a nonsteroidal SARM: it binds the androgen receptor and exerts tissue-selective agonist activity, favoring anabolic (muscle) over androgenic effects. This class mechanism was confirmed in the Phase 1 study by dose-dependent modulation of androgen-sensitive biomarkers (SHBG, total testosterone, HDL) in healthy men (PMID 27085586).
- Tissue-selective design [In vitro]. The compound was deliberately selected to perform well in a muscle (anabolic) assay while minimizing effect in an androgenic-response assay. Its pharmacophore is an isoquinoline-carbonitrile with a cyclic sulfamide (thiadiazinane 1,1-dioxide); the medicinal-chemistry strategy aimed at tissue-selective AR activity. This is a design rationale, not a demonstrated clinical safety margin.
- Testosterone (HPTA) suppression [Human]. The dose-dependent suppression of total testosterone indicates on-target androgenic feedback on the hypothalamic-pituitary- testicular axis (HPTA suppression). Maximal biomarker effects were seen at the highest multiple-dose level (100 mg twice daily) (PMID 27085586).
Section 4 of 9Research and evidence
Research and evidence
The entire human evidence base is one completed Phase 1 study. There is no efficacy trial — no human study of lean mass, physical function, or any physique/performance endpoint exists. The Phase 1 study measured safety, pharmacokinetics, and pharmacodynamics (biomarkers) in healthy volunteers only.
| Finding | Model | Source |
|---|---|---|
| Single completed Phase 1 first-in-human study: randomized, double-blind, SAD (1–400 mg) and MAD (3–100 mg BID, plus 60 mg once daily and a Japanese 30 mg BID cohort) in healthy adult men | [Human] — Phase 1 (completed) | Bhattacharya I et al., Clin Ther 2016 (PMID 27085586); NCT02070939 |
| Pharmacokinetics: rapid absorption (median Tmax ~1–2 h), half-life ~6.9–12.8 h; Japanese subjects showed markedly higher exposure (Cmax +98.6%, AUCτ +79.5% vs Western subjects) | [Human] — Phase 1 | PMID 27085586 |
| Pharmacodynamics: dose-dependent decreases in total testosterone, SHBG, and HDL cholesterol; greatest at 100 mg BID | [Human] — Phase 1 | PMID 27085586 |
| No public evidence of any Phase 2 or later development; the compound did not advance beyond Phase 1 in the public record | [Human] — none beyond Phase 1 | ClinicalTrials.gov / literature search (no later trials found) |
Human evidence in context. The only controlled human data are safety, PK, and PD in healthy men — not efficacy. Whether PF-06260414 builds muscle or improves physical function in humans is not established; no efficacy trial exists. The higher exposure in Japanese subjects is real but its metabolic/pharmacogenomic basis is not established.
Section 5 of 9Status and regulation
Status and regulation
- Regulatory approval: None. PF-06260414 is not approved by the FDA, the EMA, or any other regulator for any indication. It is investigational — a single Phase 1 study completed, with no public development beyond Phase 1. Its status is effectively discontinued/inactive in the public record, but not officially confirmed as terminated. The intended clinical indication (muscle-wasting/cachexia is the typical SARM target) was never publicly finalized for this compound.
- Anti-doping: Prohibited by the World Anti-Doping Agency (WADA) at all times (in- and out-of-competition) as a SARM, under S1.2 (Other Anabolic Agents). WADA is a sport-eligibility axis and is separate from any question of legality.
- Market reality: Outside of that single trial, any material sold under this name is an unregulated "research chemical" of unknown identity, purity, and potency.
Section 6 of 9Safety
Safety
Androgen suppression and a liver-enzyme signal — with no long-term human data
In the only human study, PF-06260414 was generally well tolerated with no serious adverse events, but the picture is short and limited. Elevated ALT (a liver enzyme) was the most frequent adverse event (7 subjects), and headache was also reported (3 subjects) [Human]. It dose-dependently suppressed total testosterone — indicating HPTA (natural testosterone) suppression, an expected on-target risk for SARMs [Human] — and dose-dependently lowered HDL cholesterol, an unfavorable lipid effect typical of androgenic agents [Human]. No long-term human safety data exist: the only human exposure is a short single Phase 1 study, so chronic effects, carcinogenicity, fertility, and cardiovascular outcomes are unstudied for this specific compound [Hypothesis].
Documented and expected safety signals (tagged by evidence type):
- Elevated ALT / liver-enzyme signal [Human]. Elevated ALT was the most frequent adverse event in the Phase 1 trial (7 subjects); headache was reported in 3 subjects. No serious adverse events occurred in this short study. Whether the ALT elevations reflected clinically significant liver injury or transient enzyme changes is not established beyond the short trial.
- Testosterone / HPTA suppression [Human]. Dose-dependent suppression of total testosterone indicates suppression of the hypothalamic-pituitary-testicular axis; androgen-suppressive endocrine effects are expected on-target risks for SARMs. No dosing, "cycle," or post-cycle guidance is given here.
- Unfavorable lipids (HDL) [Human]. HDL cholesterol decreased dose-dependently — an unfavorable lipid effect typical of androgenic agents.
- Class-level hepatotoxicity / DILI [Human — class]. The FDA has warned that products containing SARMs are associated with liver injury including cases of acute liver failure requiring hospitalization, plus increased risk of heart attack, stroke, and infertility.
- No long-term human safety data [Hypothesis]. Chronic hepatotoxicity, cardiovascular outcomes, fertility, and carcinogenicity for PF-06260414 specifically are not established — no data exist.
Contamination reality — a 'SARM' label is not a statement of contents
Van Wagoner et al. (JAMA 2017;318(20):2004-2010, PMID 29183075) chemically analyzed 44 products sold as SARMs: only 52% actually contained the labeled SARM, 39% contained a different unapproved drug, and 9% contained no active compound at all. A product sold as "PF-06260414" is therefore not reliably PF-06260414 — it may contain a different drug, or nothing. This is an independent hazard on top of the compound's own risks, and a common source of inadvertent anti-doping violations.
Section 7 of 9Legal status
Legal status
Legality not assessed here
This page does not assess the legality of buying or possessing PF-06260414 in any specific country. What is documented: it is not an approved medicine, supplement, or food ingredient anywhere, it is an investigational compound sold otherwise only as a research reagent, and it becomes an unauthorised medicine the moment it is intended for human use. Separately, it is prohibited in sport by WADA at all times. "Research chemical" status is a legal and safety gray zone — it is not a signal of safety or approval, and this is not a "milder, safer, or legal alternative" to steroids. Check your own jurisdiction; this is not legal advice, and is not a claim that the compound is safe, legal, or beneficial to take. Dated 2026-07-10.
Section 8 of 9How it compares
How it compares
PF-06260414 is often grouped with other SARMs and with non-SARM "research chemicals." The honest framing:
- Ostarine, Testolone (RAD-140), Ligandrol (LGD-4033), Andarine — other nonsteroidal SARMs that share PF-06260414's mechanism (AR modulation), testosterone- suppression risk, WADA S1.2 status, and lack of approval. Where several of those have extensive grey-market case-report data, PF-06260414's entire human record is one completed Phase 1 study — narrower, and with no efficacy data at all.
- Cardarine (GW-501516) and Stenabolic (SR9009) — frequently sold alongside SARMs but are NOT SARMs (a PPARδ agonist and a Rev-ErbA agonist, respectively). Different mechanisms entirely.
The decisive point: PF-06260414 is investigational, not approved for anything, reached only a single Phase 1 safety study, and has no human efficacy evidence for physique or performance. See the Muscle, growth & hormones overview.
Section 9 of 9Common misconceptions
Common misconceptions
- "PF-06260414 is a peptide." No. It is a synthetic nonsteroidal small molecule (C14H14N4O2S, 302.35 g/mol). It is covered here only because it is discussed and stacked with peptides.
- "It's a milder, safer, legal alternative to steroids." No. It is not approved, it suppresses natural testosterone, it lowers HDL cholesterol, and its most frequent adverse event in trial was elevated ALT (a liver enzyme). "SARM" does not mean "safe."
- "The muscle/performance benefits are proven in humans." No. The only human study measured safety, PK, and PD in healthy volunteers. There is no human efficacy trial for muscle or physical function — those benefits are not established.
- "It's an actively developed Pfizer drug." No. Pfizer ran one Phase 1 study and there is no public evidence of any further development; its status is effectively inactive.
- "Buying it as a 'research chemical' means it's clean and correctly dosed." No. Independent testing (JAMA 2017) found most products sold as SARMs were mislabeled, contained a different drug, or contained nothing.
This entry is educational and summarizes published research and public regulatory information as of the "updated" date above. It is not medical advice, not legal advice, a recommendation, or a guide to obtaining or using any substance.