Efficacy of combined treatment of intramuscular testosterone injection and testosterone ointment application for late-onset hypogonadism: an open-labeled, randomized, crossover study

Abstract

Introduction

The best method for administering testosterone replacement therapy (TRT) for late-onset hypogonadism (LOH) remains controversial. This study aimed to compare the efficacy and safety of a combined treatment (CT) involving intramuscular testosterone injection and testosterone ointment application [Glowmin^® (GL)] with intramuscular injection monotherapy (IMIM).

Materials and methods

Patients were randomly assigned as follows: Group 1 received IMIM for 12 weeks and CT for 12 weeks and Group 2 received CT for 12 weeks and IMIM for 12 weeks. Patients were then asked about their treatment preferences: (A) IMIM, (B) a combination of IMIM and ointment, or (C) either A or B.

Results

Patients (n = 43) completed the study without any adverse effects. No significant differences between each treatment period were found. In Group 1, most patients chose B (n = 13) while in Group 2, most chose A (n = 10). In each group, patients preferred the second treatment phase; however, statistical significance was not reached between A and B (Group 1, p = 0.11 and Group 2, p = 0.47, respectively).

Conclusion

TRT by CT is compatible with TRT by IMIM. Patients who cannot continue TRT because of polycythemia from IMIM may be suited to CT.

Keywords:

• Late-onset hypogonadism
• testosterone replacement therapy
• intramuscular testosterone injection
• testosterone ointment
• polycythemia

Introduction

Late-onset hypogonadism (LOH) syndrome occurs owing to testosterone deficiency in aging individuals [1]. The symptoms of LOH include diminished sexual desire and erectile quality, changes in mood with concomitant decreases in intellectual activity and spatial orientation, fatigue, depression and anger, dysuria and increased urinary frequency, decreases in lean body mass with associated decreases in muscle volume and strength, decreases in amounts of body hair and changes to skin and decreased bone mineral density resulting in osteoporosis [1–6]. The primary treatment for LOH includes testosterone replacement therapy (TRT) [7,8]. In the manuduction of Japan, an intramuscular testosterone injection and testosterone ointment [Glowmin^® (GL)] have been available for administering testosterone to patients with LOH [9]. Although the efficiency of intramuscular testosterone injection is good, several problems exist. These include transiently high levels of testosterone in blood vessels, pain from intramuscular injections [10] and the necessity for frequent visits to the hospital. In contrast, the twice daily scrotal administration of GL elevates serum testosterone levels to normal physiological concentrations [11] and can be used without pain. The efficacy of GL has been previously reported [5,11–13]; however, some patients may feel that this is an ineffective treatment owing to the mild elevation of testosterone. The combined treatment (CT) of intramuscular testosterone injection and GL may result in complementary effects. Thus, this study aimed to investigate the efficacy and safety of administering TRT through CT compared with administering TRT through intramuscular injection monotherapy (IMIM).

Materials and methods

This open-labeled, randomized, crossover study was approved by the Ethics Committee of the Kyoto Prefectural University of Medicine (clinical trial number RBMR-C-1039). Written informed consent was obtained from all patients prior to the onset of any treatments. The inclusion criteria included a diagnosis of LOH, according to the manuduction of Japan [9,14]; serum-free testosterone levels of ≤11.8 pg/ml and Aging Male Symptoms (AMS) scale scores of ≥27 at the initial visit. Exclusion criteria included the presence of prostate cancer, moderate or advanced benign prostate hyperplasia, breast cancer, polycythemia, severe kidney or liver dysfunction, severe hypertension, congenital heart failure, sleep apnea syndrome, the use of anticoagulant medication, or serum prostate specific antigen (PSA) levels of ≥4 ng/ml.

Study design

All participants were screened by a study coordinator and those who met the criteria for inclusion were randomized into one of two groups. For this study, we chose a crossover design to monitor testosterone levels during IMIM and CT with intramuscular injection and ointment (GL). Group 1 undertook IMIM with a crossover to CT. Group 2 received CT with a crossover to IMIM.

The flow of this trial is shown in Figure 1. In summary, the study was 24 weeks in duration and was divided into two phases. During the IMIM phase, patients were treated with 250 mg of testosterone enanthate by intramuscular injection every 3 weeks for 12 weeks. During the CT phase, patients were first treated with 250 mg of testosterone enanthate by intramuscular injection and, after 3 weeks, received 3 mg of testosterone ointment on the scrotal skin twice a day, in the morning and evening, for 3 weeks. Patients received each treatment in alternate shifts every 3 weeks for 12 weeks. TRT, for patients who had previously been receiving it (and whose previous TRT was IMIM), was halted 6 weeks before the trial to allow for a wash-out period. The ends of the phases were defined as periods 1 and 2. Participants received baseline assessments, which included age, body mass index (BMI), history of TRT, smoking status, drinking status and the presence of underlying diseases (diabetes, hypertension, or hyperlipidemia). The symptom questionnaires, which included details of AMS, a short version of the International Index of Erectile Function (IIEF-5), International Prostate Symptom Score (IPSS) and Overactive Bladder Symptoms Score (OABSS) were filled in at baseline and at the end of each intervention phase to determine the efficacy of each treatment strategy. The biochemical tests, which included total bilirubin, hemoglobin, hematocrit, PSA and total testosterone (TT) and FT were taken at baseline and at the end of each intervention phase to determine the efficacy and safety of each treatment strategy. At the end of this trial, patients were asked to answer questions about their preferred choice of treatment by choosing from the following three options: (A) IMIM, (B) CT involving intramuscular injection and ointment, or (C) either A or B. For this study, GL was supplied by Daito pharmaceutical company and other medical practices were financed by healthcare insurance.

Figure 1. The flow of this trial. Patients in Group 1 received testosterone replacement therapy (TRT) by intramuscular injection every 3 weeks for 12 weeks as phase 1. After that, they received TRT with combined treatment of intramuscular injection and ointment in alternate shifts every 3 weeks for 12 weeks as phase 2. Blood samples and questionnaires were obtained at baseline and after each treatment period. Patients in Group 2 received TRT in the reverse order.

Outcomes

The primary outcome was to determine whether CT was compatible with IMIM by comparing the patients’ treatment choices in each group. The secondary outcome was to evaluate the efficacy and safety of CT compared with IMIM.

Statistical analysis

Baseline comparisons of Group 1 and Group 2 were calculated using chi-squared tests for qualitative data. Quantitative data were tested for normal distribution and then assessed using t-tests for normally distributed data and Mann-Whitney U-tests for non-normally distributed data.

The intra-individual biochemical differences between the two treatment periods (crossover differences) of each group were tested for normal distribution and analyzed using t-tests for normally distributed data and Wilcoxon signed rank analysis for non-normally distributed data. The intra-individual differences in questionnaire answers at baseline and at each period were calculated by Wilcoxon signed rank analysis. The differences in treatment choice (A versus B) for Group 1 and Group 2 were statistically calculated using chi-squared goodness-of-fit tests, respectively. A 5% confidence interval was considered significant. All of the data are presented as means ± standard deviation. Statistical tests were calculated using Statcel 4 software for Microsoft Excel.

Results

A total of 52 patients with LOH were enrolled onto this study between 27 January 2012 and 12 September 2014. Overall, 48 patients completed the first phase of the treatment study and 43 patients completed the second phase. Three participants were lost to follow-up before the end of the first phase and two were lost to follow-up between periods 1 and 2. Four participants were not able to complete this study, due to the adverse effects of the intramuscular injections (palpitations) or ointment (gynecomastia), the will of the patient, or transfer of job. The final 43 patients were included in the outcome analysis (Figure 2).

Figure 2. The CONSORT flow diagram for this trial. Fifty-two patients with late-onset hypogonadism were enrolled onto this trial. The patients were randomized into two groups (Groups 1 and 2). A total of 48 patients completed the first phase and 43 finished the second phase. The data obtained from these 43 patients were included in the outcome analyses.

The baseline characteristics of each group are summarized in Table 1. Participants in Group 2 were younger than participants in Group 1 by 4.6 years. The total bilirubin level of Group 2 was higher than that of Group 1 by 0.15 mg/dL and the FT level of Group 2 was higher than that of Group 1 by 1.3 pg/ml. There were no significant differences between Group 1 and Group 2 with respect to BMI, history of TRT, smoking status, drinking status, underlying diseases (diabetes, hypertension, or hyperlipidemia), AMS score, IIEF 5 score, IPSS, OABSS, hemoglobin, hematocrit, PSA, or TT levels. The symptom questionnaires and biochemical tests of each group in periods 1 and 2 are provided in Table 2. Two participants in Group 2 were not tested for FT or TT in periods 1 or 2 and, therefore, their FT or TT data were excluded from the analysis. The total hemoglobin and hematocrit level of Group1 during period 1 was higher, by 0.3 g/dL or 1.0%, than that in period 2. The hematocrit level of Group 2 in period 1 was lower, by 1.1%, than that in period 2. There were no significant differences between period 1 and 2 with respect to AMS scale score, IIEF 5 score, IPSS, OABSS, total bilirubin, PSA level, TT level, or FT level for each group.

Table 1. Baseline clinical characteristics of patients in Groups 1 and 2.

Variable	Group 1	Group 2	Group 1 vs. Group 2
	n = 23	n = 20	p value
Age (years)	59.5 ± 7.17	54.9 ± 7.12	0.04*
BMI (kg/m^2)	22.7 ± 3.15	23.3 ± 2.89	0.49
History of TRT, n (%)	14 (61%)	11 (55%)	0.47
Smoking status, n (%)	6 (26%)	2 (10%)	0.18
Drinking status, n (%)	14 (61%)	15 (75%)	0.32
Diabetes, n (%)	4 (17%)	3 (15%)	0.83
Hypertension, n (%)	7 (30%)	2 (10%)	0.10
Hyperlipidemia, n (%)	6 (26%)	3 (15%)	0.37
AMS scale	40.6 ± 12.0	44.2 ± 11.8	0.83
IIEF 5	10.2 ± 6.6	9.7 ± 7.0	0.72
IPSS	11.3 ± 13.4	11.1 ± 8.5	0.65
OABSS	3.1 ± 3.6	3.0 ± 2.5	0.71
Total bilirubin (mg/dL)	0.64 ± 0.19	0.84 ± 0.20	0.002*
Hemoglobin (g/dL)	14.5 ± 1.34	15.0 ± 1.53	0.25
Hematocrit (%)	42.6 ± 3.70	43.8 ± 4.06	0.30
PSA (ng/mL)	1.23 ± 0.85	1.11 ± 0.72	0.73
Total testosterone (ng/ml)	2.9 ± 1.51	3.4 ± 1.00	0.22
Free-testosterone (pg/mL)	4.0 ± 2.06	5.3 ± 1.68	0.04*

Values represent mean ± standard deviation.

BMI: Body Mass Index; n: number of subjects per category; TRT: Testosterone Replacement Therapy; AMS: Aging Male Symptoms; IIEF5: short version of International Index of Erectile Function; IPSS: International Prostate Symptoms Score; OABSS: Overactive Bladder Symptoms Score; PSA: Prostate Specific Antigen.

*Significant difference between Group 1 and Group 2 (p = 0.05).

Table 2. The results from symptom questionnaires and biochemical tests of each group during periods 1 and 2.

Variable	Group 1			Group 2
	Period 1	Period 2	p value	Period 1	Period 2	p value
	12week	24week		12week	24week
AMS scale	34.4 ± 8.9	35.1 ± 8.9	0.53	39.9 ± 10.5	37.3 ± 13.0	0.24
IIEF 5	12.5 ± 7.0	12.5 ± 7.0	0.95	11.3 ± 6.3	11.3 ± 7.0	1
IPSS	8.0 ± 6.5	7.9 ± 7.0	0.83	10.7 ± 5.0	9.7 ± 7.0	0.38
OABSS	2.8 ± 2.4	2.6 ± 2.7	0.23	2.8 ± 2.1	2.7 ± 1.9	0.5
Total bilirubin (mg/dL)	0.79 ± 0.31	0.83 ± 0.27	0.51	0.87 ± 0.23	1.00 ± 0.25	0.07
Hemoglobin (g/dL)	15.3 ± 1.4	15.0 ± 1.2	0.04*	15.6 ± 1.4	15.9 ± 1.2	0.16
Hematocrit (%)	45.1 ± 3.9	44.1 ± 3.4	0.01*	45.5 ± 3.7	46.6 ± 3.6	0.03*
PSA (ng/mL)	1.28 ± 0.82	1.16 ± 0.69	0.11	1.14 ± 0.75	1.13 ± 0.78	0.54
Total testosterone (ng/ml)	2.94 ± 1.52	3.06 ± 2.16	0.90	2.77 ± 1.14	2.95 ± 1.11	0.56
Free-testosterone (pg/mL)	4.00 ± 2.02	4.21 ± 1.59	0.68	4.87 ± 2.18	4.97 ± 2.13	0.88

Values shown represent mean ± standard deviation.

*Significantly different between period 1 and period 2 (p = 0.05).

The sequential changes in results from symptom questionnaires for each group are indicated in Figure 3. The AMS scale scores for Group 1 in periods 1 and 2 and Group 2 in period 2 were lower than those at baseline. There were no significant differences in IIEF 5, IPSS and OABSS between periods. The choices of treatment in Group 1 and Group 2 are presented in Table 3. In each group, the participants preferred the second half of the treatment; however, when comparing A versus B, there was no statistical difference in Group 1, p = 0.11 or in Group 2, p = 0.47, respectively.

Figure 3. The sequential changes in results from symptom questionnaires (mean ± standard deviation), which included AMS, IIEF 5, IPSS and OABSS in each group among this trial (reference to Table 1 and 2).

Table 3. The preferred treatments of patients with LOH in Group 1 and Group 2.

	A: Intramuscular injection monotherapy	B: Combined treatment with intramuscular injection and ointment	C: Either	A versus B
			A or B	p value
Group 1	6	13	4	0.11
Group 2	10	7	3	0.47

Discussion

The efficacy of TRT for patients with LOH [7,8,15,16] has been well-reported and several therapeutic methods, such as oral administration of testosterone (testosterone undecanoate), intramuscular injections (testosterone undecanoate and testosterone enanthate), trans-dermal administration (testosterone patches and testosterone gel), buccal tablets (testosterone buccal) and crystalline testosterone (Testopel^®, Auxilium Pharmaceuticals Inc.) are available for administration of testosterone to these patients [10,13]. However, no conclusion has yet been drawn about the best method for administering testosterone to patients. This lack of confirmation may be due to the fact that each method has its own merits and demerits [10]. Additionally, CT involving each method offers possibilities of providing complementary effects.

In this study, no significant differences in the results from the symptom questionnaires for each treatment period were determined. However, 16 of the 43 participants (37%) considered IMIM to be preferable; the most frequently given reason for this preference (in 11 of 16 men, 69%) was the high effectiveness of the treatment. Furthermore, 3 of these 16 men considered a hospital visit every 3 weeks to be easier than spreading ointment on the skin every day; one felt ill-at-ease about the daily application of ointment; and one gave no answer about the reason for his choice. On the other hand, 20 of 43 participants (47%) considered CT to be their preferred treatment strategy and the most frequent reason given for making this choice (9 out of 20 men, 45%) was, as with IMIM, the high effectiveness of the treatment.

Participants in Group 1 selected CT to be preferable to IMIM, but participants in Group 2 did not. The baseline testosterone level in Group 1 was lower than that in Group 2. This suggests that patients with LOH and low levels of testosterone feel satisfied with mild elevation in testosterone levels provided by the alternate shift of the ointment [11]. Alternatively, patient satisfaction may occur due to the accumulation of testosterone through the study, because 23 of 43 participants (54%) preferred the second half of the treatment. If a wash-out period had been included between each treatment phase, the selection bias caused by the accumulation of testosterone would have been avoided. However, it should be noted that there were some participants who chose CT because of a preference for the ointment. A total of 7 of the 20 men who preferred the CT option considered the reduction in the number of intramuscular injections and hospital visits to be a better option, while one considered the stability of the treatment effectiveness using the ointment to be superior, and one considered CT to have fewer side effects than IMIM. Two of the 20 participants gave no answer about the reasons for their choices.

An additional and important consideration when determining treatment methods is the adverse effect of TRT [15]. In this study, 2 of 52 participants were not able to continue the study due to the experience of adverse effects from the intramuscular injections of testosterone (palpitations) or GL (gynecomastia). With regard to the biochemical tests, there were no adverse effects that interrupted the study; however, during the IMIM phase, the hemoglobin and hematocrit levels were higher than during the CT phase. Patients with hemoglobin or hematocrit levels elevated to polycythemic levels (hemoglobin ≥18 g/dL or hematocrit ≥53%) from the intramuscular testosterone injection may benefit from TRT using CT. Furthermore, the pain caused by intramuscular injections may be an important consideration.

Although the recommended period for TRT in patients with LOH is as yet unclear, previous reports have revealed that long-term TRT improves fasting blood sugar, hemoglobin A1c, and triglyceride level in Japanese hypogonadal men, and diminishes the risks of developing metabolic syndrome or myocardial infarctions and strokes. TRT also does not increase the incidence of prostate cancer [13,17–24]. One of these reports revealed that patients with LOH, who had received TRT over a long period of time, suffered recurrences of LOH symptoms when the TRT was interrupted [24]. Due to this phenomenon, patients with LOH may need to continue TRT throughout their lives. If this is the case, CT can prolong the intervals between treatments and reduce the required number of hospital visits.

The present study has several limitations including a small number of participants, use of the same method of TRT (intramuscular injection) during each treatment phase, and the influence of testosterone accumulation in terms of patients’ final choice of treatment. Additionally, GL was supplied free of charge by the company, whereas testosterone injection was not, which it might influence the participants’ preference. However, the subjects in each group preferred the second half of the treatment plan and, therefore, CT was considered to be compatible with IMIM and an attractive option for the administration of testosterone to patients with LOH. To the best of our knowledge, this is the first study to investigate the combination of different methods of TRT in patients with LOH.

The administration of TRT by CT can be compatible with TRT by IMIM. In particular, this strategy offers an opportunity for patients who cannot continue with TRT, due to adverse effects such as polycythemia caused by the intramuscular testosterone injection, to be treated with CT.

Acknowledgements

Glowmin^® was supplied by Daito pharmaceutical company; however, neither the results of the study, nor the statistical analyses, were influenced by this company

Disclosure statement

No potential conflict of interest was reported by the authors.