Comparison of the kinetics of injectable testosterone in eugonadal and hypogonadal men

FERTILITY AND STERIUTY Copyright c 1982 The American Fertility Society

Vol. 37, No.3, March 1982 Printed in U.8A.

Comparison of the kinetics of injectable testosterone in eugonadal and hypogonadal men

Rebecca Z. Sokol, M.D.*t Anselmo Palacios, M.D.* L. Arthur Campfield, Ph.D.:/: Cathryn Saul, B.A.:/: Ronald S. Swerdloff, M.D. * Harbor-University of California Los Angeles Medical Center, Torrance, California 90509, and University of California Los Angeles Center for Health Sciences, Los Angeles, California 90024

Serum reproductive hormone levels were measured serially after eugonadal and hypogonadal men had received either a 200-mg or a 100-mg intramuscular injection of testosterone enanthate. The calculated mean integrated testosterone and estradiol levels indicated that the 200-mg testosterone enanthate injection in the hypogonadal subjects maintained eugonadal levels of these hormones through day 11. The 100-mg . dose maintained eugonadal testosterone levels through day 7. The testosterone:estradiol ratios· in both groups following the 200-mg injection remained above or at the eugonadal baseline through day 21. The authors recommend that replacement therapy for hypogonadal men should be 200 mg of testosterone enanthate every 10 to 14 days. A similar dosage would be recommended if testosterone enanthate were to be used as an experimental inhibitor of spermatogenesis (contraceptive agent). Fertil SteriI37:425, 1982

Testosterone enanthate is considered to be a long-acting parenteral form of testosterone used primarily in the treatment of hypogonadism, oligospermia, and impotence. It is occasionally used to treat chronic anemia and has been proposed as a male contraceptive agent. Despite its reputation as a long-acting androgen and the common recommendation that it be administered every 3

Received March 23, 1981; revised and accepted September 18, 1981. *Department of Medicine, Harbor-University of California Los Angeles-Medical Center, Torrance, California 90509. tReprint requests: Rebecca Z. SokOl, M.D., Division of Endocrinology, A-17 Annex, Harbor-University of California Los Angeles Medical Center, 1000 West Carson Street, Torrance, California 90509. :j:Department of Bioengineering, University of California Los Angeles Center for Health Sciences, Los Angeles, California 90024. Vol. 37, No.3, March 1982

to 4 weeks,1, 2 the data suggest that more frequent injection has a rational basis and would result in better therapeutic responses. The present study was designed to compare the effects of testosterone enanthate administration on reproductive hormone concentrations in eugonadal and hypogonadal men. The study specifically evaluates the results of a single intramuscular injection of one of two doses of testosterone enanthate on (1) the appearance and disappearance in serum of testosterone and its metabolic product estradiol; (2) the resultant dynamic changes in the serum testosterone:estradiol ratios; and (3) the pattern of suppression and reappearance of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The data generated should provide new insights into the estimation of dose regimens of testosterone enanthate for either replacement therapy for hypogonadal men or suppression therapy for eugonadal individuals. Sokol et a!. Kinetics of injectable testosterone

425

2500

50

HORMONAL ASSAY

45

Serum samples were assayed for testosterone, estradiol, FSH, and LH with the use ofwell-characterized radioimmunoassays.3-7 Testosterone enanthate did not competitively displace tritiated testosterone in the testosterone radioimmunoassay « 0.02%).

40

2000

35 30

1500

,

."

;g'"

25 '

go

~

t-

20

---<5

1000

15

5

-I 0

A

I

3

13

II 7 9 TIME IN DAYS

5

15

17

19

21

..'"'" Z

:I:

U

!!J ~ z ~ a:

'"

ANALYSIS OF DATA

10

500

The data were analyzed within each subject, across the subjects, and by computer-based multifactorial regression to characterize the perturbations produced by a pharmacologic dose of testosterone enanthate on the male hypothalamic-pituitary-gonadal axis. The significance of changes in serum hormone values was determined by the use of two-tailed paired t-test. TESTOSTERONE PREPARATIONS

Il.

-7

-3

-I 0

4

6

8

10

12

14

16

18

20

Commercially available testosterone enanthate in sesame oil was supplied by the Squibb Corporation (E. R. Squibb & Sons, Inc., Princeton, N. J.).

TIME IN DAYS

Figure 1 (A), Mean and standard error of testosterone and estradiol levels in eugonadal men before and at various time intervals after an intramuscular injection of 200 mg of testosterone enanthate. (B), Percentage of change of LH and FSH levels in eugonadal men at various time intervals after an intramuscular injection of 200 mg of testosterone enanthate.

1400

70

1200

60

ilooo z

0

~

800

8

600

15 'i

0._

I-

~

MATERIALS AND METHODS

400

l >l

200

VOLUNTEERS

Seven eugonadal men and seven hypogonadal men, aged 18 to 40, each received a 200-mg intramuscular injection of testosterone enanthate. The hypogonadal subjects had not received testosterone therapy for at least 2 months prior to testing. After a 2- to 12-month treatment-free interval, seven eugonadal men and one hypogonadal man received a second 100-mg intramuscular injection of testosterone enanthate.

10

o

oJ-~+-~-+~~----r--+--~--~~

A

-2

-I

0

1

2

3

14

4

21

DAYS POST TE INJECTION

50

25

..is ~ z

0

t- -25

z

i-50

-75

STUDY PROTOCOL

Each subject received either a 100-mg or a 200-mg intramuscular injection of testosterone enanthate between 8:00 A.M. and 9:00 A.M. Control blood samples were drawn at - 30 minutes, -15 minutes, and again just prior to the injection. After the injection, serum samples were drawn at 6 hours, and on days 1, 2, 3, 4, 7, 9,11, 14, and 21. 426

Sokol et al. Kinetics of injectable testosterone

B

-2 -I 0

I

2 3 4

7

9

II

14

21

TIME IN DAYS

Figure 2 (A), Mean and standard error of testosterone and estradiol

levels in eugonadal men before and at various time intervals after an intramuscular injection of 100 mg of testosterone enanthate. (B), Percentage of change of LH and FSH levels in eugonadal men at various time intervals after an intramuscular injection of 100 mg of testosterone enanthate.

Fertility and Sterility

~ 1400

70~

!I200

60i'

z

~

~ 1000

a 40~

~ 800

I-~

600

P~---
400

~ WO

~

0

200-mg Dose (Fig. 3)

50(')

~

~

HYPOGONADALSUBJECTS

30~ 20

1'--

z

I~

...I-+++-++-I-+--t--+--+---+----+--..J.... -2-10 I 234 7 9 II 14 DAYS POST TE INJECTION

5

21

0

~

Figure 3

Mean and standard error of testosterone and estradiol levels in hypogonadal men' before and at various time intervals after an intramuscular injection of 200 mg of testosterone enanthate.

RESULTS

The mean baseline serum testosterone was 95 ± 10 ng/dl, peaked at 24 hours (1233 ± 484 ng/dl,

.:1 of 1138), and fell logarithmically, remaining above eugonadal baseline values through day 9 (544 ± 104 ng/dl). The levels returned to hypogonadal baseline values by day 21 (91 ± 25 ngldl). The apparent half-life was 4.2 days. The mean baseline estradiol level was 7.2 ± 2 pglml. The levels peaked at day 1 (29 ± 4 pg/ml), remained at eugonadallevels through day 9, and returned to the hypogonadal baseline on day 21. The percentage of decrement for LH and FSH was 60 ± 9%, occurring between days 2 and 9. Levels returned to the baseline by days 11 to 14 (n = 3).

EUGONADALSUBJECTS

lOO-mg Dose (One Subject) 200-mg Dose (Fig. lA and B) The basal serum testosterone was 497 ± 63 ng/dl, peaked at 6 hours (1965 ± 391 ng/dl, .:1 of 1468), and fell logarithmically, reaching baseline levels by day 9. Levels then fell slightly below baseline on day 11 (P < 0.01). The apparent halflife was 3.8 days. The basal serum E2 was 23 ± 4 pg/ml, peaked at day 2 (45 ± 4 pg/ml, .:1 of 22), reached the baseline by day 9 (20 ± 2 pg/ml), and fell below the baseline on day 11 (P < 0.02). Serum LH and FSH fell rapidly after the injection. The first decrement was on day 1 (LH, -31 ± 6%; FSH, -20 ± 7%). The nadir occurred between days 4 and 9 (LH, - 65 ± 4%; FSH, -71 ± 5%). Levels returned to baseline at 14 days.

The mean control serum testosterone was 186 ng/dl. The levels peaked at 48 hours (606 ng/dl, .:1 of 420), plateaued through day 7, and fell to the eugonadal baseline on day 9 (477 ng/dl) and to the hypogonadal baseline on day 21. The mean control serum estradiol level was 19 pg/ml. The levels peaked at 12 hours (37 pg/ml, .:1 of 18), plateaued by day 14, and fell to baseline on day 21. Serum LH levels were not suppressed by the 100-mg dose.

2000 1800 ",1600 ~

lOO-mg Dose (Fig. 2A and B)

E1400

The basal serum testosterone was 521 ± 51.2 ng/dl, peaked at 24 hours (1181 ± 204.7 ng/dl, .:1 of 660), and fell logarithmically, reaching the baseline by day 7. Levels then fell below the baseline on day 9 (P < 0.001) and day 11 (P < 0.02). Levels returned to the baseline by day 21. The basaJ serum estradiol was 28.2 ± 2.8 pgl ml, peaked at 24 hours (44 ± 4.6 pg/ml, .:1 of 16), and reached the baseline by day 7. Serum LH and FSH fell rapidly after testosterone enanthate injection. The first decrement occurred between days 1 and 2 ( - 39 ± 6% for LH and - 28 ± 9% for FSH), the nadir between days 4 and 9 (-59 ± 7% for LH and -63 ± 9% for FSH), and returned to baseline by day 14.

Q

z

Vol. 37, No.3, March 1982

~ 1200

~ ~

1000

8.... 800 ::I

ii1

600

III 400 200 100 -2-101234

7

9

II

14

21

DAYS POST TE INJECTION

Figure 4

Mean and standard error of testosterone levels in eugonadal and hypogonadal men before and at various time intervals after an intramuscular injection of 200 mg of testosterone enanthate. Sokol et aI. Kinetics of injectable testosterone

427

........ EUGONAOAL MEN HYPOGONADAL MEN

<>- -0

i

~ 50

~~ 40 ~

~30

<.>

or 20 2

~

10

-2 -I

0 1 2 34

.0

7

9

II

14

21

DAYS POST TE tlJECTION

Figure 5 Mean and standard error of estradiol levels in eugonadal and hypogonadal men before and at various time intervals after an intramuscular irijection of 200 mg of testosterone enanthate.

DISCUSSION

This study examines the pharmacokinetics of two dosages of testosterone enanthate injected intramuscularly into both normal and hypogonadal men. Our results demonstrate that in eugonadal men both dosages cause a rapid suppression of LH and FSH and a definite increase in circulating levels of serum testosterone and estradiol. The larger dose results in peak serum testosterone levels that are higher and occur earlier than that after the 100-mg dose (1965 ± 391 ng/dl at 6 hours versus 1181 ± 204 ng/dl at 24 hours). After the 200-mg dose, serum testosterone is maintained abo.ve baseline levels for 2 days longer than following the 100-mg dose. Both dosages result in a longer apparent half-life for testosterone than would have been expected had crystalline testosterone been injected intravenously as a single bolus. This finding could be explained either by continued absorption of testosterone or testosterone enanthate from the muscle depot site or by continued deesterification of circulating testosterone enanthate to testosterone. Since testosterone enanthate does not cross-react to any extent in the testosterone assay, the measured concentrations of testosterone reflect authentic hormone, not the pharmaceutical preparation. Both dosages of testosterone enanthate result in suppressed gonadotropins through day 11. Serum testosterone concentrations are below the baseline on days 9 to 11 after the 100-mg dose and on day 11 after the 200-mg dose. These results suggest that the exogenous circulating testosterone suppresses LH and FSH, which in tum re428

Sokol et aI. Kinetics of injectable testosterone

sults in a suppression of the secretion of endogenous testosterone. The corollary observation is that LH and FSH levels return to normal with secondary stimulation of production of testosterone and estradiol from the testes of the eugonadal men. The data also demonstrate that the kinetics of the 100-mg dose of testosterone enanthate parallel those of the 200-mg dose of testosterone enanthate, but the perturbations to the system are not as great. A comparison of the effects of the 200-mg dose on eugonadal and hypogonadal men reveals that the kinetics of testosterone and estradiol appearance and metabolism are similar in both groups (Figs. 4 and 5). The mean integrated testosterone and estradiol levels were also calculated and plotted at different time intervals after the 200-mg injection (Figs. 6 and 7). For both steroids, as the time interval increases, the average daily concentration falls. More importantly, the 200-mg testosterone enanthate intramuscular injection in the hypogonadal subjects maintains eugonadal levels of serum testosterone and estradiol through day 11 (Figs. 4 and 5). These values do not return to hypogonadal levels until day 21. 2000

~

1800

o

~ 1600

I

...

.s z

HYPOGONADAL MEN NORMAL MEN

M±S.E.M.

Q 1400

ti It:

I-

~

1200

u 1&.11000

~

It:

1&.1

Iii

~

800

1&.1 I-

600

1&.1

~

I±57

It:

1&.1 400

~

200 !lIZ±2.2 0

0-7

0-11

0-14

0-21

DAYS POST TE INJECTION

Figure 6 Mean integrated testosterone levels as related to time after an intramuscular injection of 200 mg of testosterone enanthate in eugonadal men. Fertility and Sterility

Q

45

-~

o I

40

HYPOGONADAL MEN NORMAL MEN M±S.E.M.

.; 35

z o

Iia: 30 ~

81&.1~ 25

I

±2.4

..J

020

~

a:

§

15

1&.1

~

ffi

~

10

m

~±2.1

5

o 0-7

0-11

0-14

0-21

DAYS POST TE INJECTION

Figure 7

Mean integrated levels as related to time after an intramuscular injection of 200 mg of testosterone enanthate in eugonadal men.

Although our study includes only one hypogonadal subject who received a 100-mg dosage, those data indicate that "the smaller dose maintains eugonadallevels of serum testosterone only through day 7. Serum estradiol levels remain above the eugonadal baseline through day 11. Serum LH is not suppressed. It therefore appears that the 100 mg testosterone enanthate replacement dosage is inadequate. Because nontreated hypogonadal men frequently have gynecomastia, which is believed to be the result of lower than normal testosterone:estradiol ratios, we calculated the subjects' testosterone:estradiol ratios at different time intervals after testosterone enanthate injection. As seen in Figures lA, 2A, and 3, there appears to be a rapid conversion of testosterone to estradiol, resulting in peak estradiol levels between 24 and 48 hours in both groups of subjects after both doses. Despite the increase in circulating estradiol levels, the testosterone:estradiol ratios in both ellgonadal and hypogonadal subjects following the" -zo6;mg testosterone enanthate injection remain above or at normal basal levels through day 21 (Fig. 8). The 100-mg injection (Fig. 9) does Vol. 37"No. 3, March 1982

not result in testosterone:estradiol ratios as high as those reached after the 200-mg injection, nor did the hypogonadal subject tested maintain a normal testosterone:estradiol ratio past the 9th day after injection . Recently, Schulte-Beerbuhl et al. B compared the serum levels of testosterone, dihydrotestosterone, LH, and FSH after an injection of either testosterone enanthate or testosterone cypionate in normal men. The doses of the two compounds were calculated to contain equal amounts of testosterone. They found that injection of either testosterone enanthate or testosterone cypionate in equivalent doses yielded identical serum testosterone concentrations, both in terms of the maximal concentrations reached and in the duration of elevation above basal levels. As in our study, maximal levels of testosterone were achieved as early as 24 hours after injection and returned to basal levels by day 9; LH levels remained suppressed through day 14. On the other hand, whereas testosterone levels fell below the baseline for days 11 to 12, serum gonadotropins did not begin to rise at the same time as they did in our stUdy. They concluded, as we did, that the interval between injections for replacement testosterone therapy should be closer to 2 weeks than to 3 weeks. Fukutani et al. 9 studied the response of serum testosterone, LH, and FSH levels to an injection of a combination of testosterone enanthate (115.7 mg) and testosterone propionate (20 mg) in two normal men. Blood samples were collected for 14 days. They also found that maximal testosterone levels were reached by 24 hours and declined to nearly pretreatment levels by days 9 to 14. The 700 ~

o

600

HYPOGONADAL ME.. NORMAL MEN

500

if 400 ::E

:::>

... 0:

UJ

300

200 100

0

~ 0

.25

2 3 4 7 DAYS POST TE INJECTION

II

14

21

Figure 8

Serum testosterone:estradiol ratios after a single intramuscular injection of 200 mg of testosterone enanthate in eugonadal and hypogonadal men. Sokol et al. Kinetics of injectable testosterone

429

I

I"'"

o~-­ ...........

ADDENDUM

MEN

o

.2lI

2

3

4

7

9

II

14

21

DAYS POST TE INJECTION

Figure 9

Serum testosterone:estradiol ratios after a single intramuscular injection of 100 mg of testosterone enanthate in eugonadal and hypogonadal men.

results of the study were obviously affected by the fact that both testosterone propionate and testosterone enanthate were injected, but the general pattern was the same as that of our study. In a study designed to evaluate the effects of androgens on sexual behavior inhypogonadal men, Davidson et a1. 10 administered either 100 mg or 400 mg of testosterone enanthate or placebo to hypogonadal men once per month for approximately 5 months. Although they did not have data on serum hormone levels immediately after injection, they did note that the levels had returned to the hypogonadal range by 2 weeks after the 100-mg dose and by 4 weeks after the 400-mg dose. They also reported that sexual activity manifested a dose-response relationship in all subjects. More erections were observed in the period after the high dose than after the low dose, and more occurred after the 100-mg treatment than after the placebo. They concluded, based on the serum hormone levels and sexual activity responses, that even high doses of testosterone enanthate should be given no less frequently than once every 3 weeks. Ideally, an androgen replacement preparation should be able to maintain physiologic levels of testosterone for extended periods of time. Unfortunately, the preparations presently available tend to result in supraphysiologic levels of testosterone followed by a semi-log linear decline to basal levels by 2 weeks. Taking into consideration these limitations and based on the data presently available, we recommend that replacement therapy for hypogonadal men should be 200 mg of testosterone enanthate every 10 to 14 days. Additionally, curve fit analysis of the LH data generated in the eugonadal men suggests that a similar dose would lead to the suppression of gonadotropins, an important factor if testosterone enanthate were to be used as a contraceptive agent. 430

Sokol et al. Kinetics of injectable testosterone

After this paper was submitted, Snyder and Lawrencel l published a study that evaluated the treatment of hypogonadal men with testosterone enanthate in doses of 100 mg per week, 200 mg every 2 weeks, 300 mg every 3 weeks, and 400 mg every 4 weeks. The treatment period ranged from 12 to 16 weeks. Based on their data, they concluded that 200 mg every 2 weeks or 300 mg every 3 weeks appeared to be the most effective regimens in terms of suppression of the serum LH concentrations to normal and the infrequency of administration. REFERENCES 1. Steinberger E: Disorders of testicular function (male hypogonadism). In Endocrinology, Edited by LJ DeGroot. New York, Grune and Stratton, 1979, p 1551 2. Styne DM, Grumbach MM: Puberty in the male and female: its physiology and disorders. In Reproductive Endocrinology, Edited by sse Yen, RB Jaffe. Philadelphia, W. B. Saunders, 1978, p 225 3. Odell WD, RoBS T, Rayford P: Radioimmunoassay for luteinizing hormone in human plasma or serum: physiological studies. J Clin Invest 46:248, 1967 4. Odell WD, Parlow AF, Cargille DM, Ross GT: Radioimmunoassay for human follicle· stimulating hormone: physiological studies. J Clin Invest 47:2551, 1968 5. Odell WD, Swerdlotr RS: Radioimmunoassay of LH and FSH in human serum. In Radioisotopes in Medicine: In Vitro Studies, Edited by RL Hayes, FA Goswitz, BE Murphy. Atomic Energy CommiBSion Symposium Series No. 13 (Conf. 67IllI), Oak Ridge, Tennessee, 1968 6. Odell WD, SwerdlotrRS, Bain J, Wollesen F, Grover PK: The effect of sexual maturation on testicular response to LH stimulation of testosterone secretion in the intact rat. Endocrinology 95:1380,1974 7. Abraham GE, Hopper K, Tulchinsky D, Swerdlotr RS, Odell WD: Simultaneous measurement of plasma progesterone, 17-hydroxyprogesterone and estradiol-17-beta by radioimmunoassay. Analyt Lett 4:325, 1971 8. Shulte-Beerbuhl M, Nieschlag E: Comparison of testosterone, dihydrotestosterone, luteinizing hormone and follicle-stimulating hormone in serum after injection of tes· tosterone enanthate or testosterone cypionate. Fertil Steril 33:201, 1980 9. Fukutani K, Isurugi K, Takayasu H, Wakabayashi K, Tamaoki B: Etrects of depot testosterone therapy on serum levels of luteinizing hormone and follicle-stimulating hormone in patients with Klinefelter's syndrome and hypogonadotropic eunuchoidism. J Clin Endocrinol Metab 39:856,1974 10. Davidson JM, Camargo CA, Smith ER: Effects of androgen on sexual behavior in hypogonadal men. J Clin EndocriJ).ol Metab 48:995, 1979 11. Snyder PJ, Lawrence DA: Treatment of male hypogonadism with testosterone enanthate. J Clin Endocrinol Metab 51:1335, 1980

Fertility and Sterility