Andarine

Biological Activity

Andarine (GTX-007) is a selective nonsteroidal androgen receptor (AR) agonist with Ki of 4 nM. It is an investigational selective androgen receptor modulator (SARM) for treatment of conditions such as muscle wasting, osteoporosis and benign prostatic hypertrophy, using the non-steroidal androgen antagonist bicalutamide as a lead compound. Andarine is less potent in both anabolic and androgenic effects than other SARMs. Andarine exhibits potent and efficacious anabolic activity and results in dose-dependent stimulation of growth in prostate, seminal vesicles, and levator ani muscle with the ED50 of 0.43 mg/day, 0.55 mg/day, and 0.14 mg/day, respectively. Andarine reduced prostate weight with similar efficacy to finasteride, but without producing any reduction in muscle mass or anti-androgenic side effects. Andarine demonstrates tissue-selective pharmacological activity and significantly decreased prostate weight to 79.4% at a concentration of 0.5 mg/day in intact rats. Andarine (GTx-007) is able to competitively block binding of dihydrotestosterone to its receptor targets in the prostate gland, but its partial agonist effects at androgen receptors prevent the side effects associated with the anti-androgenic drugs traditionally used for treatment of BPH.

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

Species	Mouse	Rat	Rabbit	Guinea pig	Hamster	Dog
Weight (kg)	0.02	0.15	1.8	0.4	0.08	10
Body Surface Area (m2)	0.007	0.025	0.15	0.05	0.02	0.5
Km factor	3	6	12	8	5	20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by	Animal B Km
	Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the K_m factor for a mouse and then divide by the K_m factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.

Chemical Information

References

Detection of the arylpropionamide-derived selective androgen receptor modulator (SARM) S-4 (Andarine) in a black-market product.
Thevis M, et al. Drug Test Anal. 2009 Aug;1(8):387-92. PMID: 20355219.