Study to Compare DITEST to Testosterone Undecanoate in Adult Men With Hypogonadism

Inclusion Criteria:

* Male subjects aged 18 to 80 years.
* Diagnosis of primary testicular failure or secondary hypogonadism due to known pituitary disease or congenital deficit.
* Body mass index (BMI) \>18kg/m2 and \<35kg/m2
* Testosterone level \<8nmol/L after washout of current testosterone treatment, if applicable.
* Normal prostate specific antigen (PSA) levels based on the age of the subject.
* Provision of written informed consent and able to participate in the study and abide by the study restrictions.

Exclusion Criteria:

* Subjects with a past history of, or current prostate cancer, male breast cancer or hepatic neoplasm.
* Subjects with a history of or current myocardial infarction (MI), unstable cardiovascular disease, or clinically relevant findings on the screening electrocardiogram (ECG) (as determined by the investigator)
* Subjects with a history of or current alcohol abuse (consumption of more than 28 units per weekweek: 1 unit equals 25mL single measure of whisky (ABV 40%), a third of a pint of beer (ABV 5-6%) or half a standard (175 mL) glass of red wine (ABV 12%).
* Subjects with other unstable or inadequately treated endocrine conditions.
* Haematocrit levels \>0.5 at baseline
* Subjects with poor dental hygiene that would interfere with the collection of saliva samples or contaminate them with blood.
* Subjects with any severe co-morbidity or with any significant medical or psychiatric conditions that in the opinion of the investigator would preclude participation in the trial.
* Participation in another clinical trial or an investigation or licensed drug or device within the 3 months prior to inclusion in this study.
* Allergic to any of the ingredients in the DITEST capsule, particularly sesame oil, or to any components of testosterone undecanoate capsules, particularly castor oil.
* Subjects with a known intolerance to alcohol (e.g. flushing) or ethnic populations at high risk of alcohol dehydrogenase (ADH) enzyme polymorphism with potential to impair metabolism of benzyl alcohol and ethanol, both of which are contained in the DITEST formulation.
* Meeting any of the contraindications for testosterone undecanoate, as detailed in the Summary of Product Characteristics (SmPC) of the comparator product.
* Subjects who are unable to consume the standard high-fat breakfast.
* Subjects who have donated blood or plasma in the previous 3 months prior to screening.
* Any subjects taking a concomitant medication known to enhance or inhibit the action of p450 CYP3A4 (rifampicin, barbiturates, carbamazepine, dichloralphenazone, phenylbutazone, phenytoin or primidone).