Consumer medicine information

Reandron 1000

Testosterone undecanoate


Brand name

Reandron 1000

Active ingredient

Testosterone undecanoate




Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Reandron 1000.


This leaflet answers some common questions about Reandron. It does not contain all the available information.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you using Reandron against the benefits they expect it will have for you.

If you have any concerns about using this medicine, ask your doctor or pharmacist.

Keep this leaflet with the medicine. You may need to read it again.


Male hypogonadism is the condition where there are low levels of testosterone in the body.

Reandron is used to replace the body’s natural hormone testosterone when not enough is made by the body.

Testosterone is a natural male hormone, known as an androgen, which controls normal sexual development in men.

Testosterone is essential for the development and maintenance of the male reproductive organs as well as other male characteristics, such as hair growth, deep voice, sexual drive, muscle mass and body fat distribution.

Reandron contains testosterone undecanoate, as the active ingredient. Reandron is injected into a location in your body (buttock muscle) where it can be stored and gradually released over a period of time.

Ask your doctor if you have any questions about why this medicine has been prescribed for you. Your doctor may have prescribed it for another reason.


When you must not be given it

Do not use Reandron if you have or are suspected to have:

  • prostate cancer
  • male breast cancer
  • high blood calcium levels associated with tumours
  • past or present liver tumours

Do not use Reandron if you are a woman.

Do not use Reandron if you have an allergy to:

  • testosterone undecanoate
  • any of the ingredients listed at the end of this leaflet

Some of the symptoms of an allergic reaction may include:

  • shortness of breath, wheezing or difficulty breathing
  • swelling of the face, lips, tongue or other parts of the body
  • rash, itching or hives on the skin.

It is not recommended to give this medicine to a child under the age of 18 years.

Do not use this medicine after the expiry date printed on the carton and vial. The expiry date is printed on the carton and on each vial after “EXP” (e.g. 11 18 refers to November 2018). The expiry date refers to the last day of that month. If it has expired return it to your pharmacist for disposal.

Do not use this medicine if the packaging is torn or shows signs of tampering. If the packaging is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should start using this medicine, talk to your doctor.

Before you start to use it

Reandron contains benzoate. Tell your doctor if you have allergies to any other medicines, foods, preservatives or dyes.

Tell your doctor if you have, or have had, any of the following medical conditions:

  • diabetes
  • a bleeding disorder
  • thrombophilia (an abnormality of blood coagulation that increases the risk of thrombosis - blood clots in blood vessels)
  • a tendency to retain fluid (signs may include swollen feet or ankles)
  • high blood pressure or if you are being treated for high blood pressure as testosterone may cause a rise in blood pressure
  • epilepsy
  • migraines
  • sleep apnoea (abnormal pauses in breathing during sleep)

If you are suffering from severe heart, liver or kidney disease, treatment with Reandron may cause severe complications in the form of water retention in your body and sometimes accompanied by (congestive) heart failure. Please inform your doctor immediately if you notice any signs of water retention.

Reandron may increase the rate of progression of prostatic tumours including benign prostatic hypertrophy (enlargement of the prostate gland) and/or prostate cancer. Before treatment, your doctor will conduct tests to ensure that you do not have prostate cancer.

People using testosterone replacement over long periods of time may develop an abnormal increase in the number of red blood cells in the blood (polycythaemia). Your doctor may organise regular blood counts to monitor this.

If you have not told your doctor about any of the above, tell them before you are given Reandron.

Athletes should note that the active substance testosterone undecanoate may produce a positive reaction in anti-doping tests.

Use of androgens for reasons other than what your doctor prescribed carries a serious health risk and is strongly discouraged.

Drug abuse and dependence:

Always take this medicine exactly as your doctor or pharmacist has told you. Abuse of testosterone, especially if you take too much of this medicine alone or with other anabolic androgenic steroids, can cause serious health problems to your heart and blood vessels (that can lead to death), mental health and/or the liver.

Individuals who have abused testosterone may become dependent and may experience withdrawal symptoms when the dosage changes significantly or is stopped immediately. You should not abuse this medicine alone or with other anabolic androgenic steroids because it carries serious health risks. (See "Side Effects".)

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including any that you get without a prescription from your pharmacy, supermarket or health food shop.

Some medicines and Reandron may interfere with each other. These include:

  • oral anticoagulants, ‘blood thinning’ medications to treat or prevent blood clots
  • medicines used to control blood sugar levels in diabetes
  • oxyphenbutazone, a medicine used to treat pain and inflammation
  • cyclosporin, a medicine used to suppress the immune system
  • barbiturates, medicines used to treat nervousness and sleeping problems

These medicines may be affected by Reandron or may affect how well it works. You may need to use different amounts of your medicine, or you may need to take different medicines. Your doctor will advise you.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while using this medicine.


Follow all directions given to you by your doctor or pharmacist carefully. They may differ from the information contained in this leaflet.

If you do not understand the instructions printed on the pharmacist label, ask your doctor or pharmacist for help.

How much is given

Reandron (1 ampoule/vial corresponding to 1000 mg testosterone undecanoate) will be injected by your healthcare professional every 10-14 weeks.

At the start of treatment your doctor will measure your blood testosterone levels. Depending on the results, the second injection may be given before 10 weeks. This is so that the necessary testosterone levels can be reached more quickly.

How it is given

The injection will be administered very slowly into your buttock muscle by your doctor.

If you are given too much (overdose)

As Reandron is given to you under the supervision of your doctor, it is very unlikely that you will receive too much. However if you experience any side effects after being given it, tell your doctor immediately. Side effects such as irritability, nervousness, weight gain, or prolonged or frequent erections may indicate the need for dosage adjustment.

Immediately telephone the Poisons Information Centre on 13 11 26 for advice, or go to Accident and Emergency at the nearest hospital, if you think that you or anyone else may have been given too much Reandron. Do this even if there are no signs of discomfort or poisoning. You may need urgent medical attention.


Things you must do

If you are about to be started on any new medicine, remind your doctor and pharmacist that you are using Reandron.

Tell any other doctors, dentists, and pharmacists who treat you that you are using this medicine.

Keep all of your doctor’s appointments.

Reandron helps control the symptoms of your condition, but does not cure it. Therefore, your doctor must administer Reandron every 10 – 14 weeks.

Your doctor may monitor your blood pressure, examine your prostate and conduct other tests from time to time, particularly if you are elderly. This is to make sure the medicine is working and to check for unwanted side effects.


Tell your doctor or pharmacist as soon as possible if you do not feel well while you are using Reandron.

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical attention if you get some of the side effects.

Do not be alarmed by the list of possible side effects. You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

High doses of Reandron may affect sperm cell development (spermatogenesis), which reduces the size of the testes. This is reversible once treatment is stopped.

Tell you doctor if you notice any of the following and they worry you:

  • weight gain
  • acne
  • enlarged prostate
  • hot flushes
  • injection site reactions such as pain or discomfort, itching, bruising, redness or irritation

These are the most common side effects of Reandron.

Tell your doctor as soon as possible if you notice any of the following:

  • depression, irritability or aggression

The above list includes serious side effects that may require urgent medical attention.

Tell your doctor immediately, or go to the Accident and Emergency department at your nearest hospital if you notice any of the following:

  • weakness, tiredness, headache, light-headedness
  • signs of allergy such as rash, swelling of the face, lips, mouth, throat or other parts of the body, shortness of breath, wheezing or trouble breathing
  • coughing, increased sweating, chest pain, feeling faint
  • yellowing of the skin and eyes, also called jaundice
  • unwanted frequent or prolonged and painful erections
  • severe stomach pain or tenderness which do not disappear within a short time
  • pain, swelling, redness, and enlarged veins in the affected area (thromboembolism)

The above list includes very serious side effects. You may need urgent medical attention or hospitalisation.

Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

Other side effects not listed above may also occur in some people.



Keep it where children cannot reach it. A locked cupboard at least one-and-a half metres above the ground is a good place to store medicines.

Store Reandron in a cool dry place where the temperature stays below 30°C.

Protect from light.

Do not store it or any other medicine in the bathroom, near a sink, or on a window-sill.

Do not leave it in the car. Heat and dampness can destroy some medicines.


If your doctor tells you to stop using this medicine or the expiry date has passed, ask your pharmacist what to do with any medicine that is left over. Return any unused medicine to your pharmacist.


What it looks like

Reandron is a clear, yellowish oily solution contained in a 5 mL glass ampoule or 6 mL glass vial.


Active ingredient:

  • Reandron 1000 – 1000 mg testosterone undecanoate per ampoule/vial

Inactive ingredients:

  • benzyl benzoate
  • castor oil


Bayer Australia Ltd
ABN 22 000 138 714
875 Pacific Highway
Pymble NSW 2073

Bayer New Zealand Limited
P O Box 2825
Shortland Street
Auckland 1140
New Zealand

Australian Registration Number

Reandron 1000 (ampoule) – AUST R 106946

Reandron 1000 (vial) – AUST R 213942

Date of preparation

Sept 2020

See TGA website ( for latest Australian Consumer Medicine Information.

See MEDSAFE website ( for latest New Zealand Consumer Medicine Information.

® Registered trademark of the Bayer Group, Germany

© Bayer Australia Ltd

All rights reserved

Published by MIMS November 2020


Brand name

Reandron 1000

Active ingredient

Testosterone undecanoate




1 Name of Medicine

Testosterone undecanoate.

2 Qualitative and Quantitative Composition

Reandron 1000 is a hormonal preparation that contains 1000 mg testosterone undecanoate in 4 mL of oily solution.
Reandron contains benzyl benzoate.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Reandron 1000 is a clear, colourless to yellowish brown oily solution for injection. Testosterone undecanoate is a white or off white crystalline substance.

4 Clinical Particulars

4.1 Therapeutic Indications

Testosterone replacement in primary and secondary male hypogonadism.

4.2 Dose and Method of Administration

Reandron 1000 (1 ampoule/ vial corresponding to 1000 mg testosterone undecanoate) is injected every 10 to 14 weeks for testosterone replacement, where testosterone deficiency has been confirmed by clinical features and biochemical tests. Injections with this frequency are capable of maintaining sufficient testosterone levels and do not lead to accumulation.
The injections must be administered very slowly. Care should be taken to inject Reandron 1000 deeply into the gluteal muscle (the only site for which clinical experience has been obtained) following the usual precautions for intramuscular administration. Reandron 1000 is strictly for intramuscular injection. Special care must be taken to avoid intravenous injection and injections must not be given subcutaneously. See Instructions for use/ handling to avoid injury when opening.

Start of treatment.

Serum testosterone levels should be measured before start of treatment and during initiation of treatment. Depending on serum testosterone levels and clinical symptoms, the first injection interval may be reduced to a minimum of 6 weeks as compared to the recommended range of 10 to 14 weeks for maintenance. With this loading dose, sufficient steady-state testosterone levels may be achieved more rapidly.

Individualisation of treatment.

The injection interval should remain within the recommended range of 10 to 14 weeks. It is advisable to measure and monitor testosterone serum levels regularly, particularly if the dosage regimen is changed or if there is clinical concern about the adequacy or excessiveness of testosterone replacement. Measurements should be performed at the end of an injection interval and clinical symptoms considered. Serum levels below normal range would indicate the need for a shorter injection interval. In case of high serum levels an extension of the injection interval may be considered or administration of a smaller volume could also be considered (i.e. could result in a shorter injection interval).
Reandron 1000 contains no antimicrobial agent. Reandron 1000 is for single use in one patient only. Discard any residue.

Instructions for use/ handling.

The product should be inspected visually for particles prior to administration. Only clear solution free from particles should be used.

Handling the one-point-cut (OPC) ampoule.

There is a pre-scored mark beneath the coloured point on the ampoule eliminating the need to file the neck. Prior to opening, ensure that any solution in the upper part of the ampoule flows down to the lower part. Use both hands to open; while holding the lower part of the ampoule in one hand, use the other hand to break off the upper part of the ampoule in the direction away from the coloured point. See Figure 1.

Handling the vial.

Flip off the protective cap (A) from the vial and aseptically clean the rubber stopper. Do not remove the metal ring (B) or the crimp cap (C). See Figure 2.

4.3 Contraindications

The use of Reandron 1000 is contraindicated in men with:
androgen dependent carcinoma of the prostate or of the male mammary gland;
hypercalcaemia accompanying malignant tumours;
hypersensitivity to the active substance or to any of the excipients;
past or present liver tumours.
The use of Reandron 1000 in women is contraindicated.

4.4 Special Warnings and Precautions for Use

Reandron 1000 should be used only if hypogonadism (hyper- and hypogonadotrophic) has been demonstrated and if other aetiologies responsible for the symptoms have been excluded before treatment is started. Testosterone insufficiency should be clearly demonstrated by clinical features (regression of secondary sexual characteristics, change in body composition, asthenia, reduced libido, erectile dysfunction etc.), confirmed by biochemical tests (2 separate blood testosterone measurements) and according to contemporary diagnostic criteria established by endocrine societies. Currently, there is no consensus about age specific testosterone reference values. However, it should be taken into account that physiologically testosterone serum levels fall with increasing age.
Due to variability in laboratory values, all measures of testosterone should be carried out in the same laboratory.
Prior to testosterone initiation, all patients must undergo a detailed examination in order to exclude the risk of pre-existing prostatic cancer. Careful and regular monitoring of the prostate gland and breast must be performed in accordance with recommended methods (digital rectal examination and estimation of serum PSA) in patients receiving testosterone therapy at least once yearly and twice yearly in elderly patients and at risk patients (those with clinical or familial factors).
Androgens may accelerate the progression of sub-clinical prostatic cancer and benign prostatic hyperplasia.
Improved insulin sensitivity may occur in patients treated with androgens who achieve normal testosterone plasma concentrations following replacement therapy.
Androgens may enhance insulin sensitivity. The dosage of the hypoglycaemic agent may need to be lowered.
Haemoglobin and haematocrit should be checked periodically in patients on long-term androgen therapy to detect cases of polycythaemia (see Section 4.8 Adverse Effects (Undesirable Effects)).
In general, the use of intramuscular injections in patients with acquired or inherited bleeding disorders is not recommended due to the risk of bleeding. Testosterone and its derivatives have been reported to increase the activity of coumarin-derived oral anticoagulants (also see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).
Testosterone should be used with caution in patients with thrombophilia, as there have been post-marketing studies and reports of thrombotic events in these patients during testosterone therapy.
Deep intramuscular injection of testosterone undecanoate is not advisable in men with any form of bleeding or coagulation disorder, including those using anti-coagulants because of the risk of haematoma. Either alternative non-injectable testosterone products should be used or expert advice sought from a haematologist (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).
Cases of benign and malignant liver tumours have been reported in users of hormonal substances, such as androgen compounds. A hepatic tumour should be considered in the differential diagnosis when severe upper abdominal pain, liver enlargement or signs of intra-abdominal haemorrhage occur in men using Reandron 1000.
Caution should be exercised in patients predisposed to oedema, e.g. in case of severe cardiac, hepatic, or renal insufficiency or ischaemic heart disease, as treatment with androgens may result in increased retention of sodium and water. In case of severe complications characterised by oedema with or without congestive heart failure, treatment must be stopped immediately (see Section 4.8 Adverse Effects (Undesirable Effects)).
Caution must be taken in patients who have had elevated blood pressure, disturbance in renal function, epilepsy or migraine. The product may elevate blood pressure. The product is not recommended for patients with cardiac insufficiency.
Pre-existing sleep apnoea may be potentiated.
Using Reandron 1000 might result in a positive finding in doping tests.
Testosterone has been subject to abuse, typically at doses higher than recommended for the approved indication(s) and in combination with other anabolic androgenic steroids.
Testosterone abuse may result in dependence and withdrawal symptoms upon significant dose reduction or abrupt discontinuation of use.
Abuse of testosterone along with other anabolic androgenic steroids can lead to serious adverse reactions including: cardiovascular (with fatal outcomes in some cases), hepatic and/or psychiatric events.
As with all oily solutions, Reandron 1000 must be injected strictly intramuscularly and very slowly. Pulmonary microembolism of oily solutions can in rare cases lead to signs and symptoms such as cough, dyspnoea, malaise, hyperhidrosis, chest pain, dizziness, paraesthesia, or syncope. These reactions may occur during or immediately after the injection and are reversible. Treatment is usually supportive, e.g. by administration of supplemental oxygen.
Suspected anaphylactic reactions after Reandron 1000 injection have been reported.
Certain clinical signs: irritability, nervousness, weight gain, prolonged or frequent erections may indicate excessive androgen exposure requiring dosage adjustment. Periodic testosterone measurements should be made during treatment, particularly when considering dose adjustment.

Clotting disorders.

Testosterone should be used with caution in patients with thrombophilia or risk factors for venous thromboembolism (VTE), as there have been post-marketing studies and reports of thrombotic events (e.g. deep-vein thrombosis, pulmonary embolism, ocular thrombosis) in these patients during testosterone therapy. In thrombophilic patients, VTE cases have been reported even under anticoagulation treatment, therefore continuing testosterone treatment after first thrombotic event should be carefully evaluated. In case of treatment continuation, further measures should be taken to minimise the individual VTE risk.

Use in hepatic impairment.

No formal studies have been performed in patients with hepatic impairment. The use of Reandron 1000 is contraindicated in men with past or present liver tumours.

Use in renal impairment.

No formal studies have been performed in patients with renal impairment.

Use in the elderly.

Limited data does not suggest the need for a dosage adjustment in elderly patients.

Paediatric use.

Clinical trials with Reandron 1000 have not been conducted in children or adolescents under the age of 18 and use in this population is not recommended.
In addition to causing masculinisation in children, testosterone can cause accelerated growth, bone maturation, and premature epiphyseal closure, thereby reducing the final height. The appearance of common acne is also expected.

Effects on laboratory tests.

Androgens may decrease levels of thyroxine binding globulin, resulting in decreased T4 serum concentrations and in increased resin uptake of T3 and T4. Free thyroid hormone levels, however, remain unchanged and there is no clinical evidence of thyroid insufficiency.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Interactions can occur with drugs that induce microsomal enzymes, which can result in increased clearance of testosterone (e.g. barbiturates).
Androgens may interfere with the metabolism of other drugs. Accordingly, plasma and tissue concentrations may be affected, e.g. increased oxyphenbutazone serum levels have been reported. The metabolism of cyclosporin might be slowed.
Moreover, testosterone and derivatives have been reported to increase the activity of coumarin derived oral anticoagulants, possibly requiring dose adjustment. Independently of this finding, the use of intramuscular injections in patients with acquired or inherited bleeding disorders is not recommended due to the risk of bleeding (see Section 4.4 Special Warnings and Precautions for Use).
Theoretically, any substance which affects liver function should not be taken with testosterone. Examples of herbal products include: Angelica dahurica, chapparal, comfrey, eucalyptus, germander tea, Jin Bu Huan, kava, penny royal oil, skullcap and valerian.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

See Section 4.8 Adverse Effects (Undesirable Effects).
(Category D)
Reandron 1000 is for use in men only and must not be used in women. Androgenic substances may have a virilising effect on the female fetus and are contraindicated during pregnancy (see Section 4.3 Contraindications).
Reandron 1000 must not be used in women and is contraindicated during lactation (see Section 4.3 Contraindications).

4.7 Effects on Ability to Drive and Use Machines

The effects of this medicine on a person's ability to drive and use machines were not assessed as part of its registration.

4.8 Adverse Effects (Undesirable Effects)

The most frequently reported adverse effects during treatment with Reandron 1000 are acne and injection site pain.
Regarding adverse effects associated with the use of androgens, please also see Section 4.4 Special Warnings and Precautions for Use.
Table 1 shows adverse drug reactions (ADRs) classified by MedDRA system organ classes (MedDRA SOCs)* reported with Reandron 1000. The frequencies are based on clinical trial data and are defined as: common ≥ 1/100 to < 1/10; uncommon ≥ 1/1000 to < 1/100.
The following ADRs were reported in six clinical trials with over 400 patients, with a suspected relationship to Reandron 1000.
Pulmonary microembolism of oily solutions can in rare cases lead to signs and symptoms such as cough, dyspnoea, malaise, hyperhidrosis, chest pain, dizziness, paraesthesia or syncope. These reactions may occur during or immediately after the injections and are reversible. Cases suspected by the company or the reporter to represent pulmonary oily microembolism have been reported rarely in clinical trials (in ≥ 1/10,000 and < 1/1,000 injections) as well as from postmarketing experience (see Section 4.4 Special Warnings and Precautions for Use).
Suspected anaphylactic reactions after Reandron 1000 injection have been reported.
In addition to the above mentioned ADRs, nervousness, hostility, sleep apnoea, various skin reactions including seborrhoea, increased hair growth, increased frequency of erections and in very rare cases jaundice have been reported under treatment with testosterone containing preparations.
Therapy with high doses of testosterone preparations commonly reversibly interrupts or reduces spermatogenesis, thereby reducing the size of the testicles; testosterone replacement therapy of hypogonadism can in rare cases cause persistent, painful erections (priapism). High dosed or long-term administration of testosterone occasionally increases the occurrences of water retention and oedema.
The following adverse events were noted during treatment in the comparative clinical study of Reandron 1000 (testosterone undecanoate) with testosterone enantate [Report No. A01198] (see Table 2).
In the literature, the following ADRs from testosterone containing preparations have been reported (see Table 3).

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at

4.9 Overdose

No special therapeutic measure apart from termination of therapy with the drug or dose reduction is necessary after overdosage.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Endogenous androgens, principally testosterone, secreted by the testes and its major metabolite dihydrotestosterone (DHT), are responsible for the development of the external and internal genital organs and for maintaining the secondary sexual characteristics (stimulating hair growth, deepening of the voice, development of the libido); for a general effect on protein anabolism; for development of skeletal muscle and body fat distribution; for a reduction in urinary nitrogen, sodium, potassium, chloride, phosphate and water excretion.
Testosterone does not produce testicular development: it reduces the pituitary secretion of gonadotropins.
The effects of testosterone in some target organs arise after peripheral conversion of testosterone to estradiol, which binds to estrogen receptors in the target cell nucleus e.g. the pituitary, fat, brain, bone and testicular Leydig cells.
Testosterone undecanoate is an ester of the naturally occurring androgen, testosterone. The active form, testosterone, is formed by cleavage of the side chain.

Clinical trials.

There were 4 pharmacokinetic studies, with 3 studies having open labelled extensions to support the dosage regimen, efficacy and safety of Reandron 1000 in the treatment of hypogonadism. The main pharmacokinetic and efficacy parameter was serum testosterone within the eugonadal range. The clinical studies included 72 men treated with Reandron 1000 (up to a maximum 36 weeks) while 60 men continued treatment longer term (range 18-33 months). Initially, the dosage regimen investigated was 6 weeks between injections (injected into the gluteal muscle) however this time interval between injections was found to be too frequent and resulted in accumulation. An optimal injection interval has not been defined and injections were administered in the extension phase of the clinical trials at intervals between 10-12 weeks. The possibility exists that supraphysiological serum testosterone levels may be attained even at the prescribed dosage regimen and the dosing interval may need to be titrated accordingly. Results from the relevant clinical studies are summarised below.

Research report no. A00315.

This was a pharmacokinetic study conducted with Reandron 1000 in 14 hypogonadal men. The dosage interval between injections was 6 weeks and 4 intramuscular injections were administered. The primary efficacy parameter was the maintenance of testosterone levels within the eugonadal range after the 4th injection. Other secondary parameters investigated were adverse events, local intramuscular tolerability, status of the prostate and urine flow and standard clinical chemistry parameters including serum lipids and prostate specific antigen (PSA). The pharmacokinetic outcomes are presented in Figure 3.
It was found that at the end of the treatment period, all men had serum testosterone levels above the lower limit of the eugonadal range. The 6 week time interval between injections resulted in accumulation of testosterone suggesting that a longer time interval between injections was required. The implication is that serum testosterone levels should be monitored to determine the optimum interval between injections. Local tolerability at the injection site (gluteus medius muscle) was investigated with injection site pain reported 3 times at the time of injection and 3 times between injection intervals. Apart from injection site pain and leg pain associated with the injection, redness and tenderness at the injections site were also reported.

Research report no. A01198.

This was a comparative study with Reandron 1000 and testosterone enantate (N = 20 per group) to investigate the efficacy and safety of treatment. Reandron 1000 was administered intramuscularly at 6 week intervals for the first 3 injections and then at a 9 week interval while testosterone enantate was administered intramuscularly at 3 week intervals over the 30 week study duration. The primary efficacy variables investigated were erythropoiesis (haemoglobin, haematocrit) and grip strength, which were similar between the groups. Multiple secondary and safety parameters were investigated including serum testosterone levels and intramuscular tolerability (also see Section 4.8 Adverse Effects (Undesirable Effects)). The pharmacokinetic results for both treatment groups are presented in Figure 4. The greater fluctuation in serum testosterone for the group treated with testosterone enantate could be due to the longer dosing interval (3 weeks) between injections.
An extension of this clinical study (research report no. A05965) was allowed whereby all patients (n = 36 initiated the extension and n = 32 completed the extension phase) were administered a further 8 intramuscular injections of Reandron 1000 (84 weeks). The pharmacokinetic results for serum testosterone in the extension phase are presented in Figure 5.

5.2 Pharmacokinetic Properties


Reandron 1000 is an intramuscularly administered depot preparation of testosterone undecanoate and thus circumvents the first-pass effect. Following intramuscular injection of testosterone undecanoate as an oily solution, the compound is gradually released from the depot and is almost completely cleaved by serum esterases into testosterone and undecanoic acid. An increase of serum levels of testosterone above basal values can already be measured one day after administration.


In two separate studies, mean maximum concentrations of testosterone of 45 and 24 nanomol/L were measured about 7 and 14 days, respectively, after single i.m. administration of 1000 mg of testosterone undecanoate to hypogonadal men. Post-maximum testosterone levels declined with an estimated half-life of about 53 days.
In serum of men, about 98% of the circulating testosterone is bound to sex hormone binding globulin (SHBG) and albumin. Only the free fraction of testosterone is considered as biologically active. Following intravenous infusion of testosterone to elderly men, an apparent volume of distribution of about 1.0 L/kg was determined.


Testosterone which is generated by ester cleavage from testosterone undecanoate is metabolised and excreted the same way as endogenous testosterone. The undecanoic acid is metabolised by β-oxidation in the same way as other aliphatic carboxylic acids.


Testosterone undergoes extensive hepatic and extrahepatic metabolism. After the administration of radiolabelled testosterone, about 90% of the radioactivity appears in the urine as glucuronic and sulphuric acid conjugates and 6% appears in the faeces after undergoing enterohepatic circulation. Urinary products include androsterone and etiocholanolone.

Steady-state conditions.

Following repeated i.m. injection of 1000 mg testosterone undecanoate to hypogonadal men using an interval of 10 weeks between two injections, steady-state conditions were achieved between the 3rd and the 5th administration. Mean Cmax and Cmin values of testosterone at steady state were about 42 and 17 nanomol/L, respectively. Post-maximum testosterone levels in the serum decreased with a half-life of about 90 days, which corresponds to the release rate from the depot.

5.3 Preclinical Safety Data


Testosterone undecanoate was not genotoxic, as assessed in vitro for reverse gene mutations and chromosomal aberrations. An in vivo assay of chromosomal damage (micronucleus test in mice) was also negative.


The potential carcinogenicity of testosterone has been tested by subcutaneous injection and implantation in mice and rats. In mice, the implant induced cervical uterine tumours, which metastasised in some cases. There is suggestive evidence that injection of testosterone in some strains of female mice increases their susceptibility to hepatoma. Testosterone is known to act as a tumour promoter and has been shown to increase carcinomas in the liver of rats. There are rare reports of hepatocellular carcinoma in patients receiving long-term therapy with androgens in high doses. Chronic androgen deficiency is a protective factor for prostatic disease and hypogonadal men receiving androgen replacement therapy require surveillance for prostate disease similar to that recommended for eugonadal men of comparable age. Elderly patients treated with androgens may be at an increased risk for the development of prostatic hyperplasia and prostatic cancer.

6 Pharmaceutical Particulars

6.1 List of Excipients

Reandron 1000 contains the excipients: benzyl benzoate and castor oil.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store Reandron 1000 below 30°C and keep out of reach of children. Protect from light.

6.5 Nature and Contents of Container

Each 5 mL glass ampoule or 6 mL glass vial contains 4 mL oily solution with 1000 mg testosterone undecanoate. Not all presentations may be marketed.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking it to your local pharmacy.

6.7 Physicochemical Properties

Chemical structure.

The chemical name for testosterone undecanoate is (17β)-17-((1-oxoundecyl) oxy)-androst-4-en-3-one and has the following structural formula:
Molecular formula: C30H48O3.
Molecular weight: 456.7.
It is practically insoluble in water and soluble in methanol and ethanol and has a melting point of 58-64°C.

CAS number.


7 Medicine Schedule (Poisons Standard)

S4 (Prescription Only Medicine).

Summary Table of Changes