Selective androgen receptor modulators (SARMs) have become a focal point in biochemical research. This is due to their unique ability to target androgen receptors in muscle and bone tissue. Plus, they do so without producing systemic side effects.
Among the most discussed SARMs in preclinical settings are S23 and RAD 140 (Testolone).
If you are into comparing these two, then this guide is prepared with you in mind. We’ll give information about how S23 and RAD 140 function as well as where they typically excel. You will also discover what their limitations are so that you can optimize your research setup.
IMPORTANT: This content is intended for research and educational purposes only. S23 and RAD 140 are classified as research compounds. They are not approved for human use. Any reference to their effects is based on animal models and in vitro studies.
What is S23 SARM?
| CAS Number | 1010396-29-8 |
| Molar Mass | 416.76 g/mol |
| Chemical Formula | C18H13ClF4N2O3 |
| Synonyms | CCTH-methylpropionamide, DTXSID701045802 |
| Half-life | ~12 hours |
Definition and Classification
S23 is a synthetic Selective Androgen Receptor Modulator (SARM). It was originally developed for its potential in male contraception and anabolic research. As a non-steroidal SARM, it selectively binds to androgen receptors. These are primarily located in skeletal muscle and bone tissue.
Mechanism of Action
S23 binds with extremely high affinity to androgen receptors. It is reportedly stronger than other SARM products such as LGD-4033 or Ostarine. Once activated, these receptors promote the following:
- Promote muscle protein synthesis
- Reduce catabolic activity
- Influence lipid metabolism
Key Potential Research Benefits
Skeletal Muscle Preservation
In one study, male rats exposed to estrogen were administered S23. Interestingly, the SARM counteracted estrogenic muscle-wasting effects. This action resulted in increased lean mass despite hormonal suppression.
Adipose Tissue Reduction and Metabolic Modulation
Based on a study of animal models, S23 has shown a dose-dependent reduction in adipose tissue. Rats administered higher doses of S23 experienced a more pronounced decrease in fat mass. Eventually, this led to reduced body weight.
Support of Bone Mineral Density and Musculoskeletal Integrity
SARMs like S23 are of interest in osteoporosis studies. This is primarily due to S23’s anabolic effects on both muscle and bone. One study concluded that S23 increased bone mineral density (BMD) regardless of dosage.
Modulation of Sexual Behavior in Estrogen-Deficient Models
Emerging evidence suggests that S23 may affect neuroendocrine regulation of sexual behavior. One study examined postmenopausal female rats.
As observed by the researchers, S23 increased markers of sexual motivation and receptivity. Moreover, this effect occurs without significantly altering the size or histology of the uterus. The latter is a common concern with testosterone treatments.
Suppression of Spermatogenesis for Contraceptive Research
S23 is currently under investigation as a potential candidate for non-hormonal male contraception. This is due to its ability to suppress luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
Among male rats, S23 led to extremely low sperm counts. It resulted in 100% infertility rates during administration. However, this effect was reversible. When discontinued, sperm production returned to normal.
Known Limitations and Observed Effects
Testosterone Suppression
One of the most notable drawbacks of S23 is its significant suppression of testosterone. This is based on preclinical studies about S23. Thus, some studies suggest a post-cycle recovery in long-term animal research.
Potential Androgenic Effects
At higher doses, androgenic side effects have been observed. This is according to relevant scientific literature.
What is RAD 140 (Testolone)?
| CAS Number | 1182367-47-0 |
| Molar Mass | 393.83 g/mol |
| Chemical Formula | C20H16ClN5O2 |
| Synonyms | Testolone, Vosilasarm |
| Half-life | ~16 hours |
Definition and Background
RAD 140 is known by its other name, which is Testolone. It is another non-steroidal SARM developed to mimic testosterone’s anabolic effects. RAD 140 is unique because it produces the mentioned result with reduced systemic impact.
Mechanism of Action
RAD 140 selectively interacts with androgen receptors found in muscle and bone tissues. This interaction occurs while not affecting reproductive organs. Considering this, RAD 140 is a potentially safer compound for long-term anabolic research.
Key Potential Research Benefits
Lipid Profile Modulation
Limited evidence suggests that RAD 140 may exert effects on lipid metabolism. In one primate study, RAD 140 was associated with cholesterol markers. However, the implications for long-term outcomes remain unclear.
Regulation of Estrogen-Responsive Cancers
RAD 140 has shown promising anti-proliferative effects. These are observed among models of hormone receptor-positive breast cancer. The SARM is said to inhibit tumor cell proliferation by suppressing ESR1. The latter is the gene responsible for estrogen receptor synthesis.
Neuroprotective Effects
RAD 140 has also demonstrated neuroprotective properties in rodent studies. In a rat model of neurotoxicity, RAD 140 is said to protect against amyloid-beta-induced neuronal damage. This effect is comparable to that of testosterone.
Anabolic Activity and Skeletal Muscle Development
RAD 140 is a well-known SARM compound thanks to its potential to enhance skeletal muscle mass. One RAD 140 study involved male cynomolgus monkeys. It lasted for 28 days, During which research subjects received a daily dose of RAD 140. The outcome is a dose-dependent increase in lean muscle tissue.
However, no human data is currently available to validate this potential effect of RAD 140.
Known Limitations and Observed Effects
Moderate Hormonal Suppression
Although less suppressive than S23, RAD 140 may still inhibit natural testosterone production.
Hepatotoxicity in Some Cases
Some researchers observed mild liver enzyme elevation. However, this is not consistently observed in other experimental literature.
S23 vs. RAD 140: Side-by-Side Comparison Table
| Feature | S23 | RAD 140 (Testolone) |
| Anabolic Potential | Extremely high | High |
| Androgenic Activity | High | Moderate |
| Suppression Risk | High | Moderate |
| Potential for Fat Loss | Strong | Moderate |
| Muscle Retention | Moderate | Moderate |
| Experimental Use Case | Cutting and contraception | Bulking and neuroprotection |
| Neuroprotective Effects | Not observed | Documented in research |
| Testosterone Recovery Need | Significant | Moderate |
Which SARM is Better for Research on Muscle Growth?
S23 vs RAD 140 for muscle growth is one of the most common research comparisons. Here’s our take:
S23 excels in producing rapid muscle hypertrophy among research subjects. This effect is often observed under caloric restriction. This SARM may be preferred in short-term, high-anabolic models. In these instances, rapid lean mass is desired.
RAD 140, on the other hand, shows the potential to support steady and selective muscle growth. This action is believed to have less impact on reproductive tissues. RAD 140 may be ideal for longitudinal studies. It may even suit research that investigates muscle preservation during aging or disease.
Our verdict: For maximum hypertrophy research, S23 is more potent. For tissue-selective growth with reduced systemic effects research, RAD 140 is a better SARM.
Which SARM is Better for Fat Loss Research?
S23 outperforms RAD 140 in this category. This is especially true in lipid metabolism and fat oxidation studies. S23 is often studied for cutting protocols. It is even paired with calorie restriction or thermogenic compounds.
RAD 140 may contribute to studies focused on recomposition. This is because the SARM indirectly reduces fat by preserving muscle. Its mechanism of action also helps improve metabolic rate. However, Testolone does not demonstrate direct fat-burning effects as S23.
Our verdict: For targeted fat loss studies, S23 is ideal. If your study tends to focus more on recomposition, RAD 140 might offer a more balanced support.
S23 vs RAD 140: Safety & Suppression
Both SARM compounds present hormonal suppression. However, they differ in the degree and implications. Here’s why:
- For S23: It demonstrates robust testosterone suppression. Thus, it may potentially complicate recovery in long-term animal studies. S23 also exhibits mild androgenic effects at high doses.
- For RAD 140: While not free from suppression, this compound is less severe and more manageable. This effect occurs when RAD 140 is dosed conservatively within controlled research studies.
Use Cases in Research Settings
| Research Context | Recommended Compound |
| Cutting Phase Models | S23 |
| Bulking/Anabolic Studies | RAD 140 |
| Performance Enhancement | Both S23 and RAD 140 |
| Cognitive Health | RAD 140 |
Where to Buy S23 and RAD 140 for Research
Why Source Matters
Research-grade SARMs must be sourced from GMP-certified, third-party tested suppliers. This practice ensures purity, consistency, and reproducibility.
Trusted Online Source: RCDbio
RCDbio is renowned for offering high-purity S23 and RAD140. Each product is validated through independent lab testing. Plus, we sell these compounds for research use only.
Conclusion
When comparing S23 vs RAD 140, each compound brings unique advantages:
- S23: This non-steroidal compound offers higher anabolic potency. This quality makes S23 excellent for fat-loss and cutting research models.
- RAD 140: Testolone comes with balanced anabolic effects. It also has the potential to provide neuroprotective value.
Your choice should align with your specific research goals, whether it’s studying hypertrophy mechanisms, fat metabolism, or neural protection.
IMPORTANT: These compounds are not intended for human or veterinary use. SARMs, such as S23 and RAD 140, are strictly for laboratory research.
FAQs
What is the difference between S23 and RAD 140?
S23 is more androgenic and potent for cutting-phase research studies. RAD 140 is more selective and may support bulking.
Is RAD 140 stronger than S23?
Not necessarily. RAD 140 is believed to be more selective. S23, on the other hand, is more potent in anabolic terms.
Which SARM has more side effects?
S23 tends to present greater testosterone suppression and androgenic effects.
Can you stack S23 and RAD 140 for research?
Some experimental designs explore SARM stacking for synergistic effects. However, this requires caution due to compounded suppression. It also presents complexity in data interpretation.
Are RAD 140 and S23 legal for lab research?
Yes, in most regions, SARMs can be legally acquired for non-human, laboratory use.
