Local tolerance, pharmacokinetics, and dynamics of ganirelix (Orgalutran®) administration by Medi-Jector® compared to conventional needle injections

J. Oberyé1, B. Mannaerts, J. Huisman and C. Timmer

Research and Development, NV Organon, Oss, The Netherlands


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The feasibility of administering a relatively high dose of the gonadotrophin-releasing hormone (GnRH) antagonist ganirelix by means of a needle-free injection device, which could be useful in the long-term treatment of sex-steroid-dependent disorders, was evaluated in a randomized, crossover study in 16 healthy females. Local tolerance and pharmacokinetics of ganirelix administered by MediJector® versus conventional needle injections were compared. Additionally, the pharmacodynamic effect was evaluated. Two milligrams of ganirelix was administered s.c. once daily for 7 days by Medi-Jector® or conventional needle in a randomized sequence, without a washout period. No apparent differences in local tolerance were observed. Most injections (87.5%) gave either no or only a mild reaction. Of the moderate reactions, swelling and redness were reported most frequently (overall 4.9 and 8.5% per injection, respectively). Administration by Medi-Jector® was bioequivalent to conventional needle injection with respect to the peak concentration and area under the curve. A profound suppression of luteinizing hormone and follicle stimulating hormone was observed. Serum oestradiol and progesterone concentrations were relatively low prior to treatment and remained low during the entire study period. In conclusion, administration of a relatively high dose of ganirelix by Medi-Jector® might be useful for long-term treatment of sex-steroid dependent disorders.

Key words: GnRH antagonist ganirelix/local tolerance/Medi-Jector®/pharmacokinetics/pituitary hormones


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Gonadotrophin-releasing hormone (GnRH) agonists are commonly used in the treatment of several sex-steroid-dependent disorders such as endometriosis and fibroids (Conn and Crowley, 1994Go). Upon repeated administration of these compounds, desensitization of the pituitary occurs, which results in decreased gonadotrophin and sex steroid concentrations.

In contrast, GnRH antagonists like ganirelix act by competition with native GnRH for the GnRH receptor binding site, and result in rapid and dose-dependent suppression of gonadotrophins (Duijkers et al., 1998Go). This mechanism of action implies that ganirelix must occupy the receptor site continuously in order to be efficacious. Considering the elimination half-life, this means that daily s.c. administration is required. However, daily injections during a long period could be experienced as a cumbersome procedure, which might compromise drug compliance. Thus, Felberbaum and colleagues tested an i.m. depot preparation in patients with symptomatic uterine fibroids, containing 60 mg of the GnRH antagonist cetrorelix which needed to be given only once every 3 or 4 weeks (Felberbaum et al., 1998Go). However, reliable pituitary suppression could not be achieved during the whole dosing interval. Therefore, another option to improve patient convenience might be an easy-to-handle, needle-free administration method for daily use with a relatively low dose.

For diabetic patients and patients with growth hormone deficiency, the Medi-Jector® has become available for self-administration of insulin (Pehling and Gerich, 1984Go) and human growth hormone (Verhagen et al., 1995Go; Houdijk et al., 1997Go). The Medi-Jector® is a needle-free injection device for s.c. delivery of medication. Under high pressure the injection solution is forced through a fine nozzle, producing a microjet that penetrates the skin. After penetration, the medication is dispersed into the subcutaneous tissue, forming an injection depot. Overall, the injection causes a minimum of discomfort for the patient. Consequently, the Medi-Jector® might be a useful device for self-administration in case of long-term treatment.

Since GnRH antagonists are known to be more prone to histamine release from mast cells and consequently give rise to more local reactions than GnRH agonists, further examination is required whether dispersion of the ganirelix solution after Medi-Jector injection causes an increased contact with these mast cells and an increased incidence or severity of local reactions. Furthermore, it needs to be studied whether dispersion alters the absorption rate.

Thus, the current study was conducted to assess the feasibility of ganirelix administration by Medi-Jector®, when compared to conventional needle injections, based on local tolerance and pharmacokinetics. Additionally, the pharmacodynamic effect of a relatively high dose of ganirelix was studied.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Volunteers
A total of 16 healthy female volunteers between 19 and 31 years of age were found eligible to participate and completed the study. Their average weight and body mass index (BMI) were 67.5 kg and 22.8 kg/m2 respectively. All women were in good physical condition and were using oral contraceptives for at least 3 months. Oral contraceptives were used for contraceptive purposes only, not for regulation of the menstrual cycle. Subjects with a history or current type I hypersensitivity (urticaria, eczema, hay fever, asthma) were excluded from participation in the study. All subjects gave written informed consent. The study was approved by the Ethics Committee of the institution and was performed in accordance with the latest revision of the Declaration of Helsinki.

Study design
This study was an open-label, randomized, crossover study in 16 healthy female volunteers to assess and compare the local tolerance and pharmacokinetics of ganirelix (Org 37462, Orgalutran®, NV Organon, Oss, The Netherlands) after administration by means of a Medi-Jector® (Medi-Ject Corporation, Minneapolis, USA) versus conventional s.c. needle injection. In addition, the pharmacodynamic effect of multiple doses of 2 mg ganirelix on endogenous hormone concentrations [luteinizing hormone (LH), follicle stimulating hormone (FSH), oestradiol, and progesterone] was investigated.

Once the volunteers were screened and found eligible to participate in the study, a comfort setting test with saline was performed to determine the optimal pressure of the Medi-Jector® for accurate drug administration. The volunteers discontinued the daily intake of contraceptive pills exactly 1 week before the first drug injection and were carefully instructed to use non-hormonal contraceptive methods during the rest of the study period. After this pill-free period, they received 2 mg ganirelix s.c. once daily during 7 days by Medi-Jector® or by conventional needle injection in a randomized sequence. There was no washout period between both treatments, as bioequivalence of the two treatments was evaluated at steady state. All injections were given in the upper leg, changing from the left to the right leg on alternating days. In view of the fact that the training period to get comfortable with the Medi-Jector® would be relatively long, compared to the treatment duration, all injections were given by physicians who were experienced in using the device. To enable frequent blood sampling, the volunteers stayed at the clinical research unit from treatment day 6 until day 8 after both administration methods.

Assessments
After completion of both treatment periods, the volunteer was requested to indicate which injection method she preferred. Local tolerance was assessed 1 and 24 h after injection by scoring each symptom (redness, swelling, bruising, pain and itching) as either none, mild, moderate or severe. Scoring of local tolerance items was performed by the medical staff, with the exception of itching and pain, which was scored by the subjects themselves. In addition, all reported adverse events were documented. Blood samples for the assessment of serum ganirelix concentrations were collected before each injection and at 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, 12, 16 and 24 h after the injection on day 7 of both treatment periods. Immediately following collection, blood samples were processed to serum, and stored at –20°C until analysis. Additionally, all blood samples taken before dosing and the 24 h sample after the last injection of the second treatment period were assayed for LH, FSH, oestradiol and progesterone.

Assay
The method of ganirelix analysis in serum has been previously described (Nerenberg et al., 1993Go). Calibration curves in the range of 0.20 to 2.56 ng/ml were linear with correlation coefficients of at least 0.99. The coefficient of variation (CV) derived from analysis of quality control samples ranged between 4.1 and 9.9%. The lower limit of quantification was 0.02 ng/ml. Serum LH, FSH, oestradiol, and progesterone concentrations were analysed by means of time-resolved fluoro-immunoassays (Delfia®, Wallac Oy, Finland). The detection limits for serum LH, FSH, oestradiol and progesterone were 0.6 IU/l, 1.0 IU/l, 13.6 pg/ml and 0.31 ng/ml respectively. The coefficients of variation (CV) derived from analysis of quality control samples for LH, FSH, oestradiol, and progesterone ranged between 1.9 and 4.3%, 0.8 and 2.3%, 4.5 and 5.4%, and 2.3 and 6.0% respectively.

Calculations and statistical analysis
A total number of 16 subjects was required to obtain a power of 83% at a significance level of 0.05, assuming a residual coefficient of variation of 20% and a ratio Test/Reference of 1. In one participant, the Medi-Jector® injection failed on days 6 and 7 of the first treatment period. As it is unknown how much of the drug has penetrated the skin after a failed injection, bioequivalence cannot be assessed. Therefore this subject was excluded from the pharmacokinetic analysis. Contrarily, for the evaluation of the feasibility of the device with respect to local reactions and pharmacodynamics, results for this subject were included.

For the local tolerance evaluation, frequency distributions per local tolerance item were calculated by administration method.

For the pharmacokinetic evaluation, the mean steady-state trough concentration (Cmin, ss), the peak concentration (Cmax) and the time of its occurrence (tmax), and the area under the concentration-time curve over one dosing interval (24 h) at steady state (AUC0–24) were determined or calculated.

Bioequivalence testing was performed with the Medi-Jector® administration as test treatment and the conventional needle injection as reference treatment. For all parameters except tmax, point estimates of the true ratio `test/reference' with their 90% parametric confidence intervals were derived from the analysis of variance (ANOVA) (Chen, 1992Go). For tmax, a point estimate of the difference between the test and reference treatment with its 90% non-parametric confidence interval was calculated using the method of Hauschke (Hauschke et al. 1992Go). The bioequivalence range was predefined as 80–125% relative to the reference range (Chen, 1992Go) for all parameters except tmax. For tmax, ± 20% of the reference arithmetic mean was used as acceptance range for the difference.

Pharmacodynamic results were presented descriptively.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Medi-Jector® performance
Of all injections given during the study, injection by Medi-Jector® failed six times (5.4%) in five volunteers. One of these failures was a technical defect of the device and no medication was administered. In all other cases, the injections were incomplete, which was obvious from a wet spot on the skin at the site of injection. At the end of the study, all volunteers were requested to indicate what method of administration they preferred. It appeared that 10 preferred the Medi-Jector® injections, two had no particular preference, and only four subjects preferred the conventional needle injection.

Local tolerance and safety
Results on local tolerance are summarized in Table IGo. Apart from a slightly increased incidence of redness after conventional needle injection (11.6 versus 5.4% by Medi-Jector®), no apparent difference in local tolerance could be observed after administration by Medi-Jector® compared to conventional needle injection. Only a few moderate or severe reactions occurred 1 h after injection. The most frequently reported moderate local tolerance items after either administration method were swelling and redness (overall 4.9 and 8.5% per injection respectively). With the exception of bruising, most reactions had decreased or disappeared at 24 h.


View this table:
[in this window]
[in a new window]
 
Table I. Percentage of injections that were scored as moderate or severe per local tolerance item at 1 and 24 h after injection by Medi-Jector® or by conventional needle and overall (16 volunteers; seven injections with each administration method)
 
Both treatments were well tolerated, with most reporting adverse events being of mild intensity. The most frequently reported adverse events were headache and hot flushes (both occurring in nine out of 16 subjects). None of the volunteers had to discontinue from the study.

Pharmacokinetics
Evaluation of the pharmacokinetic results revealed that there was no sequence effect and analysis of the pre-dose ganirelix concentrations indicated that steady state was reached from day 3 onwards (data not shown). The mean ganirelix concentration–time profile at steady state appeared to be very similar for both methods of administration (Figure 1Go).



View larger version (16K):
[in this window]
[in a new window]
 
Figure 1. Linear plot of serum concentrations during one dosing interval at steady state after multiple s.c. administration of 2 mg ganirelix by Medi-Jector® and by conventional needle (mean ± SD, 15 subjects).

 
The main pharmacokinetic parameters that were calculated from the ganirelix concentrations are presented in Table IIGo. Peak concentrations (Cmax) averaged 92.6 ng/ml and 95.6 ng/ml and occurred at 0.98 h and 1.47 h after dosing (tmax) for the conventional needle and Medi-Jector® injections respectively. Mean AUC values over one dosing interval (AUC0–24) were 775.6 and 803.7 ng.h/ml after administration by conventional needle and Medi-Jector® respectively.


View this table:
[in this window]
[in a new window]
 
Table II. Summary of pharmacokinetic parameters calculated from serum ganirelix concentrations measured after 7 days once daily s.c. administration of 2 mg ganirelix by means of Medi-Jector® or conventional needle(n = 15)
 
Bioequivalence testing revealed that the two treatments were bioequivalent with respect to all pharmacokinetic parameters, except for tmax, for which bioequivalence could not be proven because of a large variability.

Pharmacodynamics
The pharmacodynamic effect was identical for both treatment sequences (data not shown), and thus results of the two treatment sequences were not analysed separately but rather evaluated together as one group. The median pre-dose serum LH, FSH and oestradiol concentrations, assessed during ganirelix treatment, are shown in Figure 2Go. After one injection, a profound decrease of serum LH to undetectable concentrations (below 0.6 IU/l) became apparent. Median serum oestradiol concentrations were already relatively low, but decreased even further to undetectable concentrations (below 13.6 pg/ml) after one injection. For FSH, a more gradual decrease in median concentrations was observed and the limit of detection (1 IU/l) was reached on day 10.



View larger version (15K):
[in this window]
[in a new window]
 
Figure 2. Median pre-dose serum hormone concentrations during treatment [luteinizing hormone (LH) and follicle stimulating hormone (FSH) in IU/l, oestradiol in pg/ml; 16 subjects]. Note: dashed lines and open symbols indicate that median values were below the limit of detection.

 
The percentages of volunteers that had undetectable hormone concentrations during the treatment period are presented additionally in Figure 3Go. After a single injection, 50% of the subjects had serum LH and oestradiol concentrations below the limit of detection and from treatment day 5 onwards, this number had increased to more than 80%. For FSH, the effect was less pronounced and a more gradual increase in the number of subjects with undetectable FSH concentrations was observed, with the maximal effect (80% of the subjects) occurring during the last two treatment days. Progesterone concentrations remained low (median values between 0.4 and 0.6 ng/ml) during the entire treatment period, without any significant change (data not shown).



View larger version (16K):
[in this window]
[in a new window]
 
Figure 3. Percentage of subjects whose pre-dose serum luteinizing hormone (LH), follicle stimulating hormone (FSH) or oestradiol concentrations were below the limit of detection during ganirelix treatment (16 subjects).

 

    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
In the present study, the feasibility of the Medi-Jector® for multiple s.c. administrations of ganirelix was evaluated, based on local tolerance and pharmacokinetics.

Even though the women did not perform the injections themselves, most of them indicated after the study that they preferred the Medi-Jector® administration method. This is in agreement with recently published data (Verrips et al., 1998Go) which compared growth hormone (GH) administration by means of Medi-Jector® and conventional needle. On the other hand there is also a report where the Medi-Jector® device was not well accepted by the patients (Houtzagers et al., 1988Go). Probably, the main reason to explain this difference is the fact that in the latter study a Medi-Jector® device of a previous generation has been used. Meanwhile, development has continued, resulting in a newer device with improved performance and better patient acceptance.

Local tolerance data obtained in the present study confirm earlier findings, that ganirelix has only minor histamine releasing properties. Even after administration of relatively high dosages and with an administration method that produces a jet stream and thereby increases the contact with mast cells, no major injection site reactions were observed. At 1 h after injection, moderate swelling and skin redness were reported most frequently. In general, these and other reactions reported 1 h after injection, disappeared during the next 24 h, except for bruising, which is considered to be related rather to the administration method itself, than to ganirelix. Overall, the local tolerance data are in good agreement with those previously reported in the 2 mg dose group of the dose-finding study (Ganirelix dose-finding study group, 1998Go).

No difference in pharmacokinetics was observed between administration of ganirelix by means of Medi-Jector®, when compared to conventional needle injection. The concentration–time profiles appeared extremely similar and the main pharmacokinetic parameters (Css, min, AUC0–24 and Cmax) were bioequivalent, indicating that the dispersion which occurs after injection by Medi-Jector® injection does not affect the rate and extent of absorption of the drug. This is in line with other reports on human growth hormone (Verhagen et al., 1995Go; Houdijk et al., 1997Go) and insulin (Pehling and Gerich, 1984Go). Only for tmax could bioequivalence not be proven in the present study, due to a large variability in the results. However, considering the fact that the difference in tmax averaged only 0.5 h, it is unlikely that this will have any clinical implications during long-term treatment with ganirelix.

In line with the demonstrated bioequivalence of the two administration methods, the pharmacodynamic effect was identical for either treatment sequence, the suppression of ganirelix on endogenous hormone concentrations being substantial. For most subjects, LH and oestradiol concentrations were suppressed to undetectable concentrations within two days. The profound LH suppression was also reported in the dose-finding study, where 95% of all subjects in the 2 mg dose group had serum LH concentrations below 1 IU/ml at the day of HCG. FSH concentrations were also suppressed considerably, although not as rapidly and extensively as LH and oestradiol concentrations. The fact that FSH suppression is less pronounced is in agreement with previous findings on other GnRH antagonists (Hall et al., 1988Go; Fluker et al., 1991Go; Sommer et al., 1994Go) and has been explained by a longer serum elimination half-life of FSH (Jockenhövel et al., 1990Go) and a differential regulation of LH and FSH secretion in the gonadotrophe (Hall et al., 1990Go). Moreover, it can be explained by the fact that GnRH antagonists suppress bioactive (B) FSH concentrations to a larger extent than immunoreactive (I) FSH, thereby decreasing the B/I ratio (Dahl et al., 1986Go).

As a result of prior oral contraceptive use, the volunteers had relatively low serum oestradiol concentrations before the first injection (ranging between <13.6 and 94.1 pg/ml). Nevertheless, oestradiol concentrations were even further suppressed immediately after starting ganirelix treatment. The suppression appeared to be mainly LH related, which is in line with the two-cell two-gonadotrophin concept, where it is concluded that both FSH and LH are required for oestrogen synthesis. Additionally, immunoreactive instead of bioactive FSH concentrations were measured in the current study. As mentioned earlier, GnRH antagonists might suppress bioactive FSH concentrations more profoundly than immunoreactive FSH concentrations (Dahl et al., 1986Go), contributing to an even larger impairment of oestrogen synthesis. Progesterone concentrations remained low and did not change during the entire treatment period, as a result of the profound suppression of serum LH and FSH concentrations which inhibited ovulation.

Medi-Jector® injection failed six times in five volunteers, which suggests that further technical improvement of this device is warranted. Interestingly, a failed injection did not affect the extent of serum hormone suppression, indicating that daily compliance with a dose of 2 mg is not pivotal. Thus, treatment failure is expected to be limited and does not have to be a drawback in the use of the Medi-Jector® with a relatively high dose of ganirelix, especially when patients are being trained adequately prior to the start of treatment.

In conclusion, s.c. administration of 2 mg ganirelix by Medi-Jector® has been shown to be safe, well tolerated, and bioequivalent to administration by means of a conventional needle. Thus, the Medi-Jector® might be a fair alternative for self-administration during long-term treatment with ganirelix, although this needs to be further substantiated in future trials.


    Notes
 
1 To whom correspondence should be addressed at: Clinical Development Department, NV Organon, PO Box 20, 5340 BH Oss, The Netherlands

Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Chen, M.L. (1992) Guidance Statistical Procedures for Bioequivalence Studies Using a Standard Two-Treatment Crossover Design. Division of Bioequivalence, Office of Generic Drugs (OGD) of the FDA, informal communication 21 CFR 10.90 (b), July, 1992.

Conn, P.M. and Crowley, W.F. (1994) Gonadotrophin-releasing hormone and its analogs. Annu. Rev. Med., 45, 391–405[ISI][Medline]

Dahl, K.D., Pavlou, S.N., Kovacs, W.J. et al. (1986) The changing ratio of serum bioactive to immunoreactive follicle-stimulating hormone in normal men following treatment with a potent gonadotropin releasing hormone antagonist. J. Clin. Endocrinol. Metab., 63, 792–794.[Abstract]

Duijkers, I.J.M., Klipping, C., Willemsen, W.N.P. et al. (1998) Single and multiple dose pharmacokinetics and pharmacodynamics of the -20-gonadotrophin-releasing hormone antagonist Cetrorelix in healthy female volunteers. Hum. Reprod., 13, 2392–2398.[Abstract]

Felberbaum, R.E., Germer, U., Ludwig, M. et al. (1998) Treatment of uterine fibroids with a slow-release formulation of the gonadotrophin releasing hormone antagonist Cetrorelix. Hum Reprod., 13, 1660–1668.[Abstract]

Fluker, M.R., Marshall, L.A., Monroe, S.E. et al. (1991) Variable ovarian response to gonadotropin-releasing hormone antagonist-induced gonadotropin deprivation during different phases of menstrual cycle. J. Clin. Endocrinol. Metab., 72, 912–919.[Abstract]

Ganirelix dose finding study group (1998) A double-blind, randomized, dose-finding study to assess the efficacy of the gonadotrophin-releasing hormone antagonist ganirelix (Org 37462) to prevent premature luteinizing hormone surges in women undergoing ovarian stimulation with recombinant follicle stimulating hormone (Puregon®). Hum. Reprod., 13, 3023–3031.[Abstract]

Hall, J.E., Brodie, T.D., Badger, T.M. et al. (1988) Evidence of differential control of FSH and LH secretion by gonadotropin-releasing hormone (GnRH) from the use of a GnRH antagonist. J. Clin. Endocrinol. Metab., 67, 524–531.[Abstract]

Hall, J.E., Withcomb, R.W., Rivier, J.E. et al. (1990) Differential regulation of luteinizing hormone, follicle-stimulating hormone, and free alpha subunit secretion from the gonadotrope by gonadotropin-releasing hormone (GnRH): evidence from the use of two GnRH antagonists. J. Clin. Endocrinol. Metab., 70, 328–335.[Abstract]

Hauschke, D., Steinijans, V.W. and Diletti, E. (1992) A distribution-free procedure for the statistical analysis of bioequivalence studies. Int. J. Clin. Pharmacol. Ther. Toxicol., 30, (Suppl. No. 1), S37–43.[Medline]

Houdijk, E.C.A.M., Herdes, E. and Delemarre-Van de Waal, H.A. (1997) Pharmacokinetics and pharmacodynamics of recombinant human growth hormone by subcutaneous jet- or needle-injection in patients with growth hormone deficiency. Acta Paediatr., 86, 1301–1307.[ISI][Medline]

Houtzagers, C.M.G.J., Visser, A.Ph., Berntzen, P.A. et al. (1988) The Medi-Jector II: efficacy and acceptability in insulin-dependent diabetic patients with and without needle phobia. Diabetic Med., 5, 135–138.[ISI][Medline]

Jockenhövel, F., Fingscheidt, U., Khan, S.A. et al. (1990) Bio- and immunoactivity of FSH in serum after intramuscular injection of highly purified urinary human FSH in normal men. Clin. Endocrinol. (Oxf)., 33, 573–584.[ISI][Medline]

Nerenberg, C., LaFargue, J., Gee, C. et al. (1993) Radioimmunoassay of ganirelix in plasma or serum. J. Immunoassay, 14, 191–207.[ISI][Medline]

Pehling, G.P. and Gerich, J.E. (1984) Comparison of plasma insulin profiles after subcutaneous administration of insulin by jet spray and conventional needle injection in patients with insulin-dependent diabetes mellitus. Mayo Clin. Proc., 59, 751–754.[ISI][Medline]

Sommer, L., Zanger, K., Dyong, T. et al. (1994) Seven-day administration of the gonadotropin-releasing hormone antagonist Cetrorelix in normal cycling women. Eur. J. Endocrinol., 131, 280–285.[ISI][Medline]

Verhagen, A., Ebels, J.T., Dogterom, A.A. et al. (1995) Pharmacokinetics and pharmacodynamics of a single dose of recombinant human growth hormone after subcutaneous administration by jet-injection: comparison with conventional needle-injection. Eur. J. Clin. Pharmacol., 49, 69–72.[ISI][Medline]

Verrips, G.H., Hirasing, R.A., Vogels, T. et al. (1998) Psychological responses to the needle-free Medi-Jector® or the multidose Disetronic® injection pen in human growth hormone therapy. Acta Paediatr., 87, 154–158.[ISI][Medline]

Submitted on July 19, 1999; accepted on October 18, 1999.