Peak, then a long descent
At steady state the product information reports a mean peak near 37 nmol/L and a mean trough near 16 nmol/L at 10-week intervals, with meaningful variation between men.
Move your treatment to NordicTRT
Already in treatment — but still riding the peaks and troughs?
If you already receive testosterone therapy in Europe and have documented bloodwork, we can review whether a steadier protocol, easier administration and a more suitable formulation could improve the treatment experience.
The long-interval problem
One deep injection can be asked to cover three months.
Long-acting testosterone undecanoate is typically injected deep into the muscle at intervals of several weeks. Published pharmacokinetic data show a broad curve rather than a flat level, and some men notice symptoms returning before the next injection.
The trough can be felt
Energy, mood, libido and cognition may fluctuate when an individual falls back toward his symptom threshold before the next scheduled injection.
Deep intramuscular burden
A 4 mL depot must be delivered very slowly and deeply. Repeated gluteal injections can mean pain, anxiety, local irritation and cumulative tissue trauma.
Representative pharmacokinetic comparison
A broad depot curve versus smaller, frequent doses.
The red curve uses the mean steady-state peak and trough reported for long-interval testosterone undecanoate and illustrates the descent across a 10–14 week interval. The cyan curve illustrates the much narrower profile sought with individually titrated subcutaneous administration two or three times weekly.
Long-interval IM undecanoateFrequent low-volume subcutaneous dosing
Illustrative comparison, not a head-to-head clinical trial. The intramuscular curve is based on published product information for long-acting testosterone undecanoate. Frequent subcutaneous dosing is associated with comparatively stable levels, but studies directly comparing long-term safety by route remain limited: Schubert et al., JCEM 2004; McFarland et al., J Endocr Soc 2017; Figueiredo et al., JCEM 2021.
Why stability matters beyond convenience
Best practice is individual: the aim is sustained symptom control without unnecessary peaks or deficient troughs. Smaller, frequent doses may reduce hormonal fluctuation and improve day-to-day consistency. They may also reduce transient estradiol and haematocrit excursions in some men, but neither aromatisation nor erythrocytosis is eliminated—both still require clinical assessment and scheduled blood monitoring.
Smaller swings between doses
Frequent low-dose subcutaneous administration aims to keep serum testosterone in a narrower band than a large injection given every few weeks.
Pharmacokinetics of frequent SC dosing vs. 3-weekly IM depot
Haematocrit is still monitored
Some observational data associate injectable peaks with a larger haematocrit rise. A flatter profile may reduce that exposure, but erythrocytosis is not eliminated and scheduled blood monitoring remains essential.
Ohlander et al., Sex Med Rev 2018; route evidence remains limited
Flatter estradiol
Testosterone-to-estradiol conversion is dose-dependent. Smaller, more frequent doses may reduce transient swings, but they do not eliminate aromatisation; body composition, total exposure and individual biology still matter.
Lakshman et al., JCEM 2010; direct route comparisons are limited
A steadier level between doses
Large swings between doses can be felt by some men. A steadier level is one reason physicians adjust the dosing pattern.
Wu et al., EMAS, NEJM 2010
Fine needles, small volumes and carefully selected products
Subcutaneous administration can be self-injected with a fine diabetes needle, avoiding repeated deep gluteal delivery. Where clinically and legally available, physicians may select lower-viscosity products with fewer additives. Formulation, carrier tolerance and injection route are chosen for the individual; transdermal preparations are also available.
Low-viscosity formulations
Where clinically and legally available, physicians can select low-viscosity formulations with fewer additives that pass through very fine insulin needles.
Injection-site comfort
Repeated deep intramuscular injections with a large needle can cause pain, local irritation and cumulative tissue trauma. Small subcutaneous volumes avoid repeated deep gluteal delivery.
Carrier oil chosen individually
Carrier-oil sensitivity and local irritation are documented in some patients. Product selection can minimise avoidable additives, but suitability is assessed individually.
Insulin-needle subcutaneous dosing
Studies have found subcutaneous administration to give testosterone levels comparable to intramuscular injection, and many men find it easier to self-administer with a fine needle.
Creams as an alternative
For men and women who prefer no needles, the physician can consider transdermal testosterone applied daily to the skin.
Science based, doctor prescribed
Our approach is science based and doctor prescribed. Treatment is considered only when symptoms and repeated blood tests confirm a deficiency, and it is followed with regular monitoring.
Transfer request
Tell us where you are treated today, what you use and what is not working. We reply within one working day.