US regulators have rejected Lipocine’s Tlando, a testosterone replacement therapy for adult males with hypogonadism.

In a complete response letter, the US Food and Drug Administration said the treatment could not be approved in its current form.

The CRL outlines four issues that need addressing before a re-submission.

For one, the firm must determine the extent, if any, of ex vivo conversion of testosterone undecanoate to testosterone in serum blood collection tubes to confirm the reliability of the data.

Also, definitive evidence must be obtained - via an ambulatory blood pressure monitoring study - on whether Tlando causes a clinically meaningful increase in blood pressure in hypogonadal men.

Lipocine should also verify the reliability of Cmax data and determine the appropriate stopping criteria that can identify those patients who should discontinue use of the therapy.

The firm said it was disappointed with the decision but that the deficiencies identified were within its expectations following a prior advisory committee meeting, and that it would now request a meeting with the FDA to further evaluate the deficiencies raised and to agree on way forward for potential approval.