It hinges on a question that maybe hasn't been answered yet: Does Sustanon behave the same as if its different esters were injected separately? Or is it more like a single unique ester with a half-life that is some average of the half-lives of its constituent esters? If the latter then daily injections probably lead to virtually unchanging daily testosterone levels, as would usually be the case with enanthate and cypionate. However, if the esters in Sustanon retain their differing absorption rates then a more substantial dairy variation would be possible. I recently came up with a guesstimate for un upper limit on this variation: +/-15% about the mean.
Does Sustanon behave the same as if its different esters were injected separately?
It does as it was designed to provide a fast yet extended release of testosterone due to the esters used as 2 are short acting (propionate and phenylpropionate) which are responsible for the short lived peak, 1 is medium acting (isocaproate) and 1 is long acting (decanoate) which are both responsible for the extended release/duration of action.
Keep in mind Sustanon 250 was designed to offer a therapeutic advantage over existing single esters of testosterone such as enanthate or cypionate which need to be injected more frequently.
Top it off with the fact that it was meant to be injected at the full 250 mg/ml dose roughly every 3 weeks when treating androgen insufficiency......and as we know this would be a horrible protocol.....let alone injection frequency.
According to the manufacturer/package insert:
4.2 Dose and method of administration
In general, the dose should be adjusted according to the response of the individual patient.
Dose Adults (incl. elderly):
Usually, one injection of 1 ml per three weeks is adequate.
Paediatric population: Safety and efficacy in children and adolescents, have not yet been established. Pre-pubertal children treated with SUSTANON should be treated with caution (see Warnings and Precautions). SUSTANON contains benzyl alcohol and is contraindicated in children under 3 years of age.
Method of administration
SUSTANON should be administered by deep intramuscular injection
Sustanon 250 is designed to provide a rapid peak in testosterone levels (24-48 hours after injection), and maintain physiological concentrations for approximately 21 days. Each 250 mg ampule provides 176 mg of testosterone.
As you can see from the graph below:
Testosterone concentrations obtained from patients while on intramuscular injection are shown in
Fig. 3. The peak concentration obtained ranged from
42-121 nmol/l (
mean 71 nmol/l) and occurred
24-48 h after the injection. The mean concentration fell to within the normal male range after one week and fell to the lower limit of the normal male range after 21 days. The overall mean T level was 27.7 nmol/l.
You can see 7 days following a 250 mg/ml injection T levels are in the normal male range and by day 21 are at the lower limit of the normal male range.
However, if the esters in Sustanon retain their differing absorption rates then a more substantial dairy variation would be possible. I recently came up with a guesstimate for un upper limit on this variation: +/-15% about the mean.
They do retain their individual absorption rates.....mind you it has been shown that injections using mixed testosterone esters such as Testoviron, Sustanon increases the initial testosterone peak compared to a single ester and also produces a much wider fluctuation of serum T levels compared to a single ester after multiple dose injections.....
(Testoviron Depot 100 (110 mg testosterone enanthate and 25 mg testosterone propionate = 100 mg unesterified testosterone) every 10 d and 139 mg testosterone enanthate (= 100 mg unesterified testosterone) every 10 d.
11.3.4 Testosterone ester combinations
Testosterone ester mixtures have been widely used for substitution therapy of male hypogonadism
(e.g. Testoviron Depot 50: 20 mg testosterone propionate and 55 mg testosterone enanthate; Testoviron Depot 100: 25 mg testosterone propionate and 110 mg testosterone enanthate; Sustanon 250: 30 mg testosterone propionate, 60 mg testosterone phenylpropionate, 60 mg testosterone isocaproate and 100 mg testosterone decanoate). These combinations are used following the postulate that the so-called short-acting testosterone ester (e.g testosterone propionate) is the effective testosterone for substitution during the first days of treatment and the so-called long-acting testosterone (e.g. testosterone enanthate) warrants effective substitution for the end of injection interval. However, this assumption is not supported by the pharmacokinetic parameters of the single testosterone esters. Both testosterone propionate and testosterone enanthate cause highest testosterone serum concentrations shortly after injection (Fig. 11.2 and Fig. 11.4). Accordingly, addition of testosterone propionate to testosterone enanthate only increases the initial undesired testosterone peak and worsens the pharmacokinetic profile that ideally should follow zero-order kinetics (Fig. 11.7). The computer simulation agrees well with the limited published single dose testosterone values that have been measured in hypogonadal patients treated with the combination of testosterone propionate and testosterone enanthate. Maximal increases of approximately 40 nmol/L testosterone over basal values are described one day after intramuscular administration of a testosterone ester combination of 115.7 mg testosterone enanthate and 20 mg testosterone propionate to three hypogonadal patients (Fukutani et al. 1974).
A comparison of computer-simulated testosterone serum concentrations after multiple dose injections of Testoviron Depot 100 (110 mg testosterone enanthate and 25 mg testosterone propionate = 100 mg unesterified testosterone) every 10 d and 139 mg testosterone enanthate (= 100 mg unesterified testosterone) every 10 d is shown in Fig. 11.8. As can be expected by the single dose kinetics of the individual esters, injection of the testosterone ester mixture (upper panel) produces a much wider fluctuation of testosterone serum concentrations relative to injection of testosterone enanthate alone (lower panel). This simulation shows that the injections of testosterone enanthate alone produce a more favourable pharmacokinetic profile in comparison to injections of testosterone propionate and testosterone enanthate ester mixtures in comparable doses. For treatment of male hypogonadism there is no advantage in combining short- and long-acting testosterone esters.
Keep in mind this is based off computer simulation using single dose injection and multiple dose injections (every 10 days)
As we know injecting more frequently will result in achieving more stable blood levels.
Now regarding daily injections using a mixed ester such as Sustanon 250 which contains 4 different esters of T.....there should be some daily variation but to what degree as we need to keep in mind what dose of T from each individual ester is being injected daily.....as an example when using the most commonly prescribed 250 mg/ml strength the overall dose contains:
2. QUALITATIVE AND QUANTITATIVE COMPOSITION
Name and strength of the active substances -
testosterone proprionate 30mg
testosterone phenylpropionate 60mg
testosterone isocaproate 60mg
testosterone decanoate 100mg
All four compounds are esters of the natural hormone testosterone.
The total amount of testosterone per 1 mL is 176mg.
So the
250 mg of esterified T in Sustanon =
176 mg active T
Now say one is injecting 20 mg of Sustanon 250 daily than one would be injecting a measly 2.4 mg propionate along with 4.8 mg of phenylpropionate, 4.8 mg isocaproate and 8 mg decanoate.
Overall you would be injecting 7.2 mg of the shorter acting esters and 12.8 mg of the medium/long acting esters.
Now going back to the original poster of this thread he is only injecting 10 mg daily which would result in an extremely low dose of propionate 1.2 mg along with a measly 2.4 mg of phenylpropionate, 2.4 mg isocaproate and 4 mg decanoate.
Overall he would be injecting 3.6 mg of the shorter acting esters and 6.4mg of the medium/long acting esters.