Product Information

Registration Status: Active

ANDRIOL TESTOCAPS is approved to be sold in Singapore with effective from 1990-05-23. It is marketed by MSD PHARMA (SINGAPORE) PTE LTD, with the registration number of SIN04606P.

This product contains Testosterone Undecanoate 40mg in the form of CAPSULE, LIQUID FILLED. It is approved for ORAL use.

This product is manufactured by CATALENT FRANCE BEINHEIM SA in FRANCE.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Testosterone Undecanoate


Testosterone undecanoate is an esterified form of testosterone which is attached to a long fatty acid chain. The lack of a methylated site on the carbon 17 eliminates the adverse effects on the liver found in other testosterone analogs.[L1164] It is currently getting further developed to be an alternative to testosterone enanthate or testosterone cypionate by Paddock labs, and this new injectable has an FDA status of tentative approval. The original approval by the FDA of a product from testosterone undecanoate was done in 1953.


Testosterone undecanoate is indicated as a testosterone replacement therapy in adult males that present conditions of deficiency or absence of endogenous testosterone. The approved conditions for the use of testosterone undecanoate are 1) primary hypogonadism, defined as a testicular failure due to cryptorchidism, bilateral torsion, orchitis, vanishing testis syndrome, orchiectomy, Klinefelter's syndrome, chemotherapy or toxic damage from alcohol or heavy metals: or 2) hypogonadotropic hypogonadism caused by idiopathic gonadotropin or luteinizing hormone-releasing hormone deficiency or pituitary-hypothalamic injuries from tumors, trauma or radiation.[FDA label]

Mechanism of Action

The effects of testosterone in humans and other vertebrates occur by way of two primary mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of specific estrogen receptors. Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5-alpha-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5-alpha-reductase. The T-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.[A949]


The absorption of testosterone undecanoate relies on the presence of fat as it is only soluble in it. Thus, the bioavailability of this testosterone derivative is very low of just 7%.[A31633] This highly lipophilic profile delineates the absorption of testosterone to be done via the lymphatic system.[L1164] The reported Cmax in steady state for testosterone undecanoate is 32 nmol/L after 7 days of administration.[A31629]
The distribution of testosterone undecanoate was limited to the liver, kidney and large and small intestine. Half of the administered dose remain near the injection site after 8 weeks of injection.[L1165] Following intravenous infusion of testosterone undecanoate, the reported volume of distribution was approximately 1 L/kg.[L1155]
To start its activity, testosterone undecanoate has to be processed by enzymes in the bloodstream. These enzymes will break the bond between the ester part of the molecule and the testosterone. Once separated, testosterone is metabolized to 17-keto steroids through two different pathways. The major active metabolites are estradiol and dihydrotestosterone (DHT). Testosterone is metabolized to DHT by steroid 5α-reductase in skin, liver and urogenital tract. In reproductive tissues, DHT is further metabolized to androstanediol.[L1152]


After intravenous administration of testosterone undecanoate, the observed clearance rate was 24.5 ml min/kg. This clearance rate indicated a fast metabolic elimination and explained the low bioavailability of this derivate of testosterone.[A31633]


Preclinical trials have shown induction of uterine tumors as well as an increase in the susceptibility to hepatoma. Testosterone undecanoate is known to increase the number of tumors and differentiation of chemically induced carcinomas. Administration of exogenous testosterone reversibly suppresses spermatogenesis.[L1165]

Active Ingredient/Synonyms

Testosterone undeconate | Testosterone undecylate | Testosterone undecanoate |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank