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Тestosterone undecanoate (TU) is now available in two forms – a long-lasting injection and an oral capsule. Although both products treat hypogonadism, they do so in different ways and should not be used interchangeably. In this review, we provide full information about testosterone undecanoate, including its usage, description, warnings, and clinical pharmacology.
In any format, testosterone replacement therapy (TRT) is a complex therapy. TRT is not to be undertaken lightly or by those who do not use it. While mainstream testosterone therapy is exceptionally effective and safe for individuals with diagnosed testosterone deficiency, it can be dangerous to people who abuse it for purposes such as bodybuilding or athletic enhancement.
Some pharmaceutical manufacturers also offer co-pay assistance programs to qualified individuals to help offset the cost of treatment. Unlike the more affordable options of testosterone cypionate (TC) and testosterone enanthate (TE) injections, testosterone undecanoate is a costly medication and one that is rarely covered by insurance. That means high out-of-pocket costs to those who desire its use.
What is the difference between oral and injectable testosterone undecanoate?
Injectable TU (AVEED) is for use by men with all forms of hypogonadism. Oral testosterone undecanoate should only be used in cases of underlying medical conditions such as where a tumor has damaged the pituitary gland or if someone has Klinefelter syndrome. Oral TU, JATENZO, does carry additional risks of use, as we will discuss further down in this article. JATENZO and AVEED are not for use by women.
Testosterone undecanoate is available as an injectable and an oral capsule to treat various forms of hypogonadism. It is available as the injectable AVEED, and as the oral capsule JATENZO.
AVEED is the brand name for injectable testosterone undecanoate. It is an intramuscular injection that contains pharmaceutical testosterone cleaved to the undecanoate ester. TU consists of a molecular weight of 456.7, and its structural formula is C30H48O3. Testosterone undecanoate is a white to off-white crystalline powder, that when mixed with a solution containing refined castor oil and benzyl benzoate, appears as a yellowish, clear oily solution.
Testosterone undecanoate delivers physiological amounts of exogenous testosterone to approximate normal circulating testosterone concentrations in men. Following initial administration, maximum testosterone concentrations occur after approximately seven days, slowly tapering off. The second dosage of TU occurs at week four, then every ten weeks following, providing a steady testosterone concentration for ten weeks. The half-life of TU is approximately 33.9 days.
JATENZO, the oral capsule form of testosterone undecanoate, requires twice-daily treatment, taken with dietary fat.
- 158 mg capsules are opaque red with a “158” imprint in white.
- 198 mg capsules are opaque white with a “198” imprint in red.
- 237 mg capsules are opaque orange with a “237” imprint in white ink.
The gelatin capsules also contain sorbitol, glycerin, purified water, titanium dioxide, FD&C Yellow #6, and iron oxide red.
Attention! Possible Allergic Reactions
Testosterone undecanoate injections carry warnings that are not seen with other testosterone formulations. Doctors must advise patients of the risk of serious pulmonary oil microembolism (POME) reactions before starting treatment. POME effects could occur during or directly following the injection of AVEED, and may include:
- Coughing or the urge to cough
- Chest pain
- Shortness of breath
- Throat tightening
These issues may last for minutes or up to several hours, potentially necessitating emergency care of hospitalization. POME reactions could occur after initial or subsequent treatments, even if there have been no problems in the past.
Some reports of anaphylactic reactions have also been life-threatening. Patients who choose to receive AVEED must remain at the medical facility for at least 30 minutes following the treatment.
JATENZO carries warnings of higher blood pressure levels, which can increase the risk of developing major adverse cardiovascular events.
Testosterone Undecanoate Instructions
As with all other forms of testosterone therapy, testosterone undecanoate provides benefits that improve sleep, energy, metabolism, body composition, bone and muscle structure, brain functions, and heart health. However, there is much to know about testosterone undecanoate before beginning treatment.
AVEED is indicated for the treatment of men who have low testosterone levels.
- Primary hypogonadism may be congenital or acquired and has to do with disorders of the testes. Congenital causes may include undescended testicles, varicocele, gene mutation, myotonic dystrophy, chromosomal abnormalities, or cryptorchidism, or Klinefelter’s syndrome. Acquired causes may consist of chronic systemic illness, environmental toxins, radiation, infections, glucocorticoid use, steroid abuse, autoimmune damage, testicular torsion, ketoconazole, testicular tumor, alkylating agents, chemotherapy, or alcohol abuse.
- Secondary and tertiary hypogonadism have to do with problems associated with the pituitary gland and hypothalamus, respectively. Congenital causes include conditions such as Prader Willi syndrome, Kallmann’s syndrome, and unknown issues. Acquired causes include a tumor of the pituitary gland or hypothalamus, surgery or radiation to treat the tumor, traumatic brain injury, other issues affecting pituitary or hypothalamic functions. Chronic opioid abuse, steroid use, diabetes, obesity, and other causes may also influence testosterone decline.
Signs of low testosterone – indications that treatment may be necessary – include:
- Weight gain
- Muscle loss
- Low sex drive
- Erectile dysfunction
- Hair thinning or loss
- High cholesterol
- Bone loss
- Joint pain
- Elevated blood pressure
- Insulin resistance
JATENZO is indicated for men who have low testosterone levels due to specific medical conditions.
Dosage & Administration
This medication is given through the Risk Evaluation and Mitigation Strategy (REMS) restricted program, also called the AVEED REMS Program. Treatment is through an intramuscular injection deep into the gluteal muscle. Extreme care is necessary to avoid intravascular administration as that can increase POME risk. The injection must avoid contact with the sciatic nerve and superior gluteal arteries.
Oral TU is taken twice daily with food (dietary fat is necessary). The doctor determines the dosage on an individualized basis. Periodic blood testing to assess dose adjustment is necessary with Jatenzo.
Storage and Use
There is no at-home storage or use for AVEED, as this medication is only given in medical settings.
Store JATENZO capsules at room temperature in a dry place away from moisture and out of reach of children and pets.
The following medications may interact with testosterone undecanoate:
- Oral anticoagulants
- Insulin and other diabetes medications
Medications that can increase blood pressure levels may lead to further problems with JATENZO use due to its risk of raising blood pressure levels.
Warnings & Precautions
Unlike TC and TE, testosterone undecanoate injections carry a serious warning for pulmonary oil microembolism (POME) reactions and anaphylaxis. POME reactions can include dizziness, chest pain, an urge to cough, throat tightening, syncope, and dyspnea. Reports of anaphylaxis, including life-threatening reactions have occurred during or following TU administration.
Whereas testosterone cypionate and testosterone enanthate offer safe self-administration at home, TU requires an injection in a doctor’s office or medical facility. The patient must remain at the facility for at least 30 minutes following the treatment in the event of a serious anaphylactic or POME reaction requiring immediate medical intervention. Even if the first treatment causes no reaction, future issues could occur at any time during the course of therapy.
Testosterone undecanoate use is contraindicated in the following situations:
- Men with prostate or breast cancer
- Hypersensitivity to any ingredients in the medication
- Pregnant or breastfeeding women
Other potential risks include:
- Polycythemia – hematocrit increase due to elevated red blood cell levels
- Venous thromboembolism – deep vein blood clots
- Worsening of benign prostatic hyperplasia (BPH)
- Increased cardiovascular risk
- Decreased sperm count – infertility
- Liver or kidney problems
- Worsening of sleep apnea
JATENZO use requires hematocrit testing every three months to check red blood cell count and guard against the development of polycythemia in addition to the above concerns. Depression and suicidal ideation have been reported during JATENZO clinical trials. JATENZO may increase blood pressure levels and the risk of major cardiovascular events such as non-fatal stroke, non-fatal myocardial infarction, and cardiovascular death. Periodic monitoring of blood pressure levels should begin within three weeks of initiating treatment or any dosage change.
Typical testosterone side effects include:
- Injection site reactions (redness, pain, irritation, swelling, itching, bruising)
- Oily skin
- Elevated estrogen levels
- Worsening of sleep apnea
- Male breast enlargement (gynecomastia)
- Fluid retention
- Urinary changes
- Frequent or prolonged erections
- Changes in weight
- Depression or mood swings
- Changes in libido
- PSA increase
Additional side effects of oral JATENZO include:
- Reduced HDL cholesterol levels
- High blood pressure
- Heart attack
- Cardiovascular death
Suffering an overdose from AVEED is unlikely as it is given in a medical facility. However, if a person also uses testosterone as a steroid, an overdose is possible. Significant adverse reactions could occur in this situation, including:
- Cardiac arrest
- Major depression
- Liver or kidney toxicity and reactions
- Aggressive actions
- Testicular atrophy
- Cerebrovascular events
An overdose could occur by taking higher than the maximum recommended dosage of Jatenzo.
- AVEED comes in 750 mg/3mL amber glass, single-use vials
- JATENZO comes in 158 mg, 198 mg, and 237 mg strengths
Due to the increased risk of adverse reactions, our doctors do NOT recommend testosterone undecanoate for use.
The mechanism of action of testosterone undecanoate is identical to that of endogenous testosterone. Testosterone has far-reaching effects on metabolism, hair growth, red blood cell production, sexual functions, fat distribution, brain functions, insulin sensitivity, glucose regulation, muscle protein synthesis, bone cell production and resorption, and emotional well-being.
Upon administration of testosterone undecanoate, the hypothalamus registers the higher level of testosterone in the bloodstream and decreases signals to the pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Without adequate supplies of LH and FSH, the testes decrease the production of testosterone and spermatozoa. That is why men who wish to conceive must discuss testosterone use and the possibility of a lower sperm count with their physician. Other treatments may be necessary to increase natural testosterone production to support sperm cell maturation.
Our hormone doctors do not prescribe testosterone undecanoate for use in any form. Through many years of research and treating both men and women for low testosterone, they believe that other types of TRT provide better results with reduced side effect risks – and at significantly lower costs.
To learn more about your options for treating low testosterone, please contact our hormone clinic for a free consultation by phone.