Use of a Calcium Channel Blocker to Prevent Premature Luteinizing Hormone Surges in Infertility Patients
Information source: Mount Sinai Hospital, Canada
Information obtained from ClinicalTrials.gov on February 07, 2013
Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Infertility
Intervention: Nimodipine (Drug); Placebo (Drug)
Phase: Phase 2
Status: Not yet recruiting
Sponsored by: Mount Sinai Hospital, Canada
Official(s) and/or principal investigator(s):
Robert F Casper, MD, Principal Investigator, Affiliation: Toronto Centre for Advanced Reproductive Technology and University of Toronto
Robert F Casper, MD, Phone: 416-972-0777, Email: firstname.lastname@example.org
Nimodipine (Nimotop® Bayer Pharmaceuticals Corporation), unlike other calcium channel
blockers is fat soluble and therefore is able to cross the blood-brain barrier1.
Gonadotropin releasing hormone (GnRH) neurons are clustered in the hypothalamus and are
dependent on calcium flux to release GnRH responsible for the release of
follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
In a natural menstrual cycle a spontaneous LH surge occurs mid-cycle which triggers
ovulation. The investigators hypothesized that nimodipine, by blocking calcium channels, may
effectively suppress the release of GnRH and consequently the natural LH surge.
In this prospective double-blinded randomized study the investigators will evaluate the
efficacy of nimodipine to inhibit the natural LH surge in women undergoing controlled
ovarian stimulation (COS) and intrauterine insemination (IUI). Nimodipine, if successful,
may represent an inexpensive oral medication as an alternative to the currently used GnRH
agonists or GnRH antagonists in assisted reproductive technologies like IVF.
Official title: Using Nimodipine, a Calcium Channel Blocker, to Prevent the LH Surge and Ovulation in Women Undergoing Assisted Reproduction
Study design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator), Primary Purpose: Treatment
Primary outcome: Delay of LH surge by at least 2 days
Secondary outcome: Side effect profile of nimodipine or placebo.
In reproductive aged women regular ovulatory cycles generate 1-2 mature ovarian follicles
every month. Approximately mid-cycle a natural LH surge is observed and predictably induces
ovulation within 24-36 hours. LH is a hormone produced by the anterior pituitary gland and
is released in response to GnRH. Concurrently GnRH is synthesized and released in a
pulsatile manner from GnRH neurons within the hypothalamus.
One of the essential steps of successful IVF is to ensure the properly timed aspiration of
mature follicles from the ovaries prior to ovulation. If ovulation were to precede
aspiration then the oocytes would have already been released and become unobtainable.
Therefore inhibiting spontaneous ovulation is a crucial component of successful oocyte
retrieval. In the clinical setting of IUI no oocyte retrieval is required, but appropriate
timing of insemination with respect to ovulation is critical.
A premature LH surge and subsequent premature luteinization may occur in up to a third of
ovarian stimulation cycles using gonadotropins (applicable to both IUI and IVF cycles),
making it a major cause of treatment cancellation and having a negative impact on pregnancy
outcomes 2-5. The most commonly used medications to prevent a premature LH surge are GnRH
agonists and more recently GnRH antagonists. They are both commonly administered
subcutaneously on a daily basis and act on the anterior pituitary gland (through different
mechanisms) to inhibit the release of LH. Besides the additional patient cost and burden,
these medications are associated with prolonged treatment protocols and decreased ovarian
response to stimulation.
Nimodipine is a unique calcium channel blocker with lipophilic properties and a greater
affinity for cerebral vasculature, and therefore has the ability to cross the blood-brain
barrier. In a study on mice with induced intracerebral hemorrhage, nimodipine treatment
improved cerebral bloodflow and displayed anti-ischemic effects. Nimodipine has obtained FDA
approval to reduce the severity of neurological deficits in patients who have had a recent
On a cellular level nimodipine has been shown to inhibit the pulsatile activity of GnRH gene
expression, an intrinsic property of GnRH neurons that is necessary for proper initiation of
the LH surge. Specifically, nimodipine blocks L-type voltage gated calcium channels which
prevent the influx of extracellular calcium and subsequently the stimulation of GnRH
release. The intrinsic pulsatile secretion of GnRH has been directly associated with the
rhythmic changes in intracellular calcium concentration in GnRH neurons.
Study Objectives and Endpoints
1. To determine if nimodipine can effectively inhibit the natural LH surge in women
undergoing controlled ovarian stimulation and intrauterine insemination.
2. To determine the medication side effect profile of nimodipine, specifically symptoms of
hypotension, tachycardia, nausea or headache.
3. To determine the treatment compliance rate (nimodipine or placebo).
4. To determine the clinical pregnancy rate for each intervention arm (nimodipine or
placebo) during the COS and IUI treatment cycle.
1. The presence or absence of an LH surge on intervention Day 1 and Day 2. LH surge will
be determined by serum LH levels at least two times the baseline serum LH.
Baseline serum LH = (Cycle Day 3 serum [LH] + Cycle Day 7 serum [LH]) /2.
2. Medication side effect profile:
- Symptomatic hypotension [Note: vital signs will not be routinely recorded]
- Symptomatic tachycardia [Note: vital signs will not be routinely recorded]
- Nausea (self-reporting; constructed questionnaire)
3. Patient treatment compliance (self-reporting; constructed questionnaire)
4. Clinical Pregnancy (positive BHCG and ultrasound evidence of fetal heart rate)
Recruitment / Baseline Assessment The study population will be derived from a pool of
patients referred to TCART (Toronto Centre for Assisted Reproductive Technology; Toronto,
Canada). Patients that have been comprehensively evaluated for infertility and subsequently
recommended to undergo controlled ovarian stimulation and intra-uterine insemination will be
approached and recruited to participate in the study. Patients will be screened and
evaluated for eligibility (based on the inclusion and exclusion criteria) by direct contact
from one of the dedicated study investigators or dedicated research staff.
Randomization Randomization will be computer generated in a block design of 6 patients. Six
corresponding opaque envelopes that enclose the blinded medication will be administered
sequentially to consenting patients. Randomization will be performed at the start of the COH
cycle and consequently the data will be analyzed as an intention-to-treat analysis.
Blinding Procedures Both patients and medical staff will be blinded to the treatment arms.
Both the nimodipine (30 mg po qid) and placebo groups (placebo po qid) will receive 8
identical tablets with the same instructions for self-administration. The capsules will be
only be identified by a unique study number to allow accurate analysis at the end of the
study. A single pharmacy will be responsible for blinding, labeling and packaging the
medication. Only the study coordinator (DN), who will not be involved clinically with study
participants, will remain unblinded.
Drug Formulation NimotopÂ® (Nimodipine) Bayer Pharmaceuticals Corporation. Calcium channel
blocker. 30mg oral soft gelatin capsules.
Dosage Regimen Nimodipine is rapidly absorbed after oral administration reaching a peak
concentration within one hour. It has a half-life of approximately 1-2 hours and a terminal
clearance half-life of 8 hours, and thus requires relatively frequent administration. It is
currently approved for the acute treatment of subarachnoid hemorrhage, with a dosing regimen
of 60mg po q4h for 21 consecutive days. Several pharmacokinetic studies have focused on 30mg
doses three times daily with no evidence of accumulation.
In our study intervention will be initiated once ovarian follicle maturation has been
documented (â‰¥1 ovarian follicle size of â‰¥ 17mm) and the absence of a premature LH surge has
been confirmed - this will be classified as intervention day 0. Patients will receive oral
nimodipine 30mg four times daily over a two day period with the following dosing schedule:
- Intervention Day 0 - noon / afternoon / bedtime (3 doses)
- Intervention Day 1 - morning / noon / afternoon / bedtime (4 doses)
- Intervention Day 2 - morning (1 dose)
Washout Period Nimodipine is eliminated almost exclusively in the form of metabolites. Less
than 1% is recovered in the urine as unchanged drug. Over 95% of the medication is bound to
plasma proteins. Nimodipine has a half life of 1-2 hours, with terminal elimination half
life of approximately 8 hours. It should be completely eliminated from the body in about 40
Contraindications to Nimodipine use
- Hypersensitivity to the active substance or to any of the excipients of Nimodipine.
- The use of Nimodipine in combination with Rifampicin
Precautions to Nimodipine use
- Caution is required in patients with hypotension
- Nimodipine is metabolized by the cytochrome P450 3A4 system, therefore drugs (or
grapefruit juice) that are known to either inhibit or to induce this enzyme should be
taken into account, including:
- Quinupristin / Dalfopristin
- Valproic Acid
Secondary Outcome variables:
- Side effects - Nausea, headache, lightheadedness, dizziness, diaphoresis, presyncopal
- Treatment compliance - Number of tablets taken (out of the prescribed 8 tablets),
appropriate timing of medication (as instructed)
- Clinical pregnancy â†’ positive bHCG serum test 2 weeks post IUI and ultrasound
documentation of a fetal heart rate
Study - Delayed Ovulation Induction and Monitoring:
- Deviating from routine practice, our study protocol will call for a two-day delay in
the hCG injection after the ultrasound detection of a mature ovarian follicle
(intervention day 0). At this time point patients will have already been randomized and
blinded to receive nimodipine 30 mg po qid, or placebo po qid for two days to ideally
prevent the natural LH surge for a further 48 hours.
- During the two day period all study patients (nimodipine or placebo) will continue to
be monitored daily at the clinic (mornings of day 1 and day 2) which will include
transvaginal ultrasound and serum measurements of estradiol, LH and progesterone.
- If during the two day period an LH surge is detected during daily morning monitoring
(eg. on day 1 or on day 2), the standard protocol of ovulation induction and IUI will
be initiated - injection of hCG 250 mcg that same afternoon and two IUIs performed 16
hours and 40 hours after hCG injection. Participant will discontinue taking their
assigned medication after an LH surge has been detected.
- If an LH surge is not detected during daily monitoring on day 1, the patient will
continue taking their assigned medication and with daily monitoring.
- If an LH surge is not detected during daily monitoring by day 2, ovulation will be
induced that same afternoon (~5 pm) by the injection of hCG 250 mcg followed by a
single IUI 40 hours later.
Safety and Adverse Events Patients undergoing COS and IUI are regularly monitored for
optimal treatment response and timing of IUI. Therefore investigators in this study will
also have the opportunity to closely observe any safety or adverse events associated with
the two-day duration of active intervention (nimodipine 30mg po qid x 48 hours).
Specifically all patients will be asked about medication (nimodipine and placebo) compliance
and side effects experienced during the morning cycle monitoring (day 1 and day 2).
Nimodipine has traditionally been investigated at higher does, frequencies and longer
duration. According to the product monograph1, a dosing regimen of nimodipine 60mg po q4h
resulted in the following side effects: hypotension (3. 8%), nausea (1. 2%), headache (1. 2%)
and bradycardia (1%). Conservative management consisted of discontinuing nimodipine and
generally was effective in reversing the symptoms.
Data Analysis Plan / Statistical Plan Data will be expressed as mean +/- SD or percentage
where applicable. Independent samples will be compared using the Student t test. The
chi-squared test and Fisher exact test will be used for categorical data. A P value of <0. 05
will be considered to indicate statistical significance.
Sample Size and Power Sample size calculations were performed using the computer program PS:
Power and sample size calculation by William Dupont. We are planning a study of independent
samples of treatments and controls with a 1: 1 randomization. Expert opinion / prior data
suggest that approximately 50% of patients in the placebo arm will have a natural LH surge
detected on day 2 post intervention after a follicular maturation has been reached15. If 20%
of patients in the nimodipine arm have a natural LH surge detected on day 2 post
intervention, then we will need 38 subjects in each of the study arms to reject the null
hypothesis (both groups have equal incidence of natural LH surge on day 2 post intervention)
with a power of 0. 8 and a type I error probability of 0. 05. We anticipate approximately a
15% dropout rate leading to a total recruitment of 90 patients (45 per study arm).
Minimum age: 25 Years.
Maximum age: 40 Years.
Inclusion Criteria: Infertility requiring intrauterine insemination
- Age: 25-40 (at time of enrollment)
- Intact Normal Ovaries (Both)
- Early follicular phase (day 2-4) serum FSH level < 20 mIU/ml
- Diagnosis of infertility with a recommended treatment of ovarian stimulation and IUI
- BMI > 38 kg/m2
- Early follicular phase (day 2-4) serum FSH level â‰¥ 20 mIU/ml
- Overstimulated cycle: >3 mature follicles (â‰¥17 mm)
- Abnormal uterine cavity and /or tubal blockage
- Diagnosis of infertility with a clear indication for IVF
- Severe male factor infertility: Total Motile Sperm Count < 2x106 post washing
Locations and Contacts
Robert F Casper, MD, Phone: 416-972-0777, Email: email@example.com
Toronto Centre for Advanced reproductive Technology (TCART), Toronto, Ontario M5S2X9, Canada; Not yet recruiting
Robert F Casper, MD, Phone: 416-972-0777, Email: firstname.lastname@example.org
Yaakov Bentov, MD, Phone: 416-972-0110, Email: email@example.com
Robert F Casper, MD, Principal Investigator
Starting date: July 2012
Last updated: October 25, 2012