Is addition of N-Acetyl Cysteine to Clomiphene
Citrate Beneficial for Ovulation Induction in
Neha Garg1 and Vanitha VG2
1Department of Obstetrics and Gynecology, Postgraduate, JJM Medical College, India
2Department of Obstetrics and Gynecology, Professor, JJM Medical College, India
Submission: April 02, 2019; Published: May 22, 2019
*Corresponding author: Neha Garg, Junior Resident, Department of Obstetrics and Gynaecology, JJM Medical College, Davangere, Karnataka, India
How to cite this article: Neha G, Vanitha V. Is addition of N-Acetyl Cysteine to Clomiphene
Citrate Beneficial for Ovulation Induction in
Anovulatory Infertility?. Glob J Reprod Med. 2019; 6(5): 555697. DOI:10.19080/GJORM.2019.06.555697.
Background: Anovulation is the major cause of infertility; seen in around 15% of infertile couples and in 40% of women with infertility. Clomiphene citrate has been the gold standard drug for ovulation induction in anovulatory infertility. However, as a singular drug it is not equally effective in all situations. The introduction of an anti-oxidant, N- acetyl cysteine to ovarian stimulation has proven to have many benefits.
Objective: To compare the efficacy of combination of clomiphene citrate with N-acetyl cysteine vs clomiphene citrate alone for augmenting ovulation in anovulatory infertility cases.
Materials and Method: 117 cases of primary and secondary infertility with anovulation were taken after ruling out other causes of infertility. Patency of bilateral fallopian tubes were confirmed by hysterosalphingography or laparoscopic chromopertubation or sonosalphingography. Their male partners were confirmed to have adequate seminal parameters according to WHO guidelines. Cases were randomized into two groups. Starting on day 3 of menstrual cycle, group CC-NAC (56 patients) were given tablet clomiphene citrate 100mg/day and tablet N-acetyl cysteine 1200mg/day orally and group CC (61patients) were given tablet clomiphene citrate alone 100mg/day for 5 days. Transvaginal ultrasound on day 14th- 16th of the cycle were done for follow up. Advice for timed intercourse daily around the time of ovulation was given. Main outcomes like number and size of growing follicles, endometrial thickness, ovulation rate and pregnancy rate were compared.
Results: Ovulation and conception rate were higher in CC-NAC group (96.42%;72.22%) than with CC group (90.16%; 34.54%); (p=0.23; p<0.01 respectively). Endometrial thickness was found to be higher in CC-NAC group (12.19 ± 1.36mm) as compared to CC group (10.17 ± 1.01mm). Clinical pregnancy rate was 94.87% in the combination group which was statistically higher than in CC group (78.94%); p< <0.001. with addition of NAC, lesser cases of multiple pregnancy and miscarriage rates (12.82%; 5.12%) than in CC group (31.57%; 21.05%); = 0.06. However, our study was limited to 3 treatment cycles. No cases of ovarian hyperstimulation were reported.
Conclusion: N-acetyl cysteine may be a novel adjuvant to clomiphene citrate, more effective than clomiphene citrate alone in inducing and augmenting ovulation. It could be used as an alternative to other insulin sensitizing agents like metformin.
Infertility has been a growing global public health issue. It affects one in every six couples, which is 15% couples in reproductive age group. Female factor infertility accounts for 40% . Around 15% of all infertile couples and in 40% of infertile women anovulation is the cause . Clomiphene citrate has been traditionally used as the first line drug in anovulatory infertility. But as a singular drug it may not be effective in all cases. Thus, the need for an adjuvant which is a drug or a substance that enhances the activity of another or a substance added to a medicinal
preparation to assist the action of the principal ingredient. Aspirin, L-arginine, oestrogens, glucocorticoids, spironolactone, cyproterone acetate, dehydroepiandrosterone, metformin, etc. are some of the adjuvants being used. Considering the high prevalence of insulin resistance and hyperinsulinemias as the most common etiological factors for resistance to clomiphene as seen in most cases of anovulatory infertility because PCOS contributes about 80% of cases with anovulation. Attention is being given to adjuvants with insulin-sensitizing properties . Recently, N-acetyl cysteine (NAC) was suggested as one of such adjuvants
. The encouraging preliminary reports and the myriad of
actions of NAC prompted us to investigate its effects on promoting
the action of clomiphene citrate on ovulation.
To investigate the effects of N-acetyl cysteine in promoting the
augmenting effects of clomiphene citrate on ovulation in all cases
of anovulatory infertility by comparing the efficacy of combination
of clomiphene citrate with N-acetyl cysteine vs clomiphene citrate
ii. Patients with tubal blockage identified at HSG,
laparoscopic chromopertubation, or sonosalphingography
iii. Clinical evidence of hyperprolactinemia,
hypercortisolism, or thyroid dysfunction
iv. Patients with unexplained infertility
v. Male infertility
vi. Patients refused participation as per our protocol
After getting IEC clearance from the institute and written
informed consent from the patients enrolled in our study, they
were subjected for thorough examination for confirmation of
anovulation [5,6], as the cause for infertility. These patients were
either given oral contraceptive pill (OCPs) if they came within 5
days of their menses or progesterone pills if they had a history of
previous amenorrhea after ruling out pregnancy. In next menstrual
cycle, within 3 days of their menses, ovulation induction using two
different regimens were started for them.
i. Group CC: 61 cases were given tablet clomiphene citrate
alone 100 mg/day orally from day 3 to day 7 of the menstrual
ii. Group CC-NAC: 56 cases were given tablet clomiphene
citrate 100 mg/day along with tablet N-acetyl cysteine 1200
mg/day orally from day 3 to day 7 of the menstrual cycle.
• Follow up – All the patients were asked to report back on
9th to 16th day of menstrual cycle. Transvaginal ultrasound for
follicular development and endometrial thickness was done
on 14th-16th day of the cycle. Advice for timed intercourse
daily around the time of ovulation was given.
• But if a dominant follicle was not found in both the
ovaries and multiple small follicles were found less than
10mm, we considered that she would not ovulate in that cycle
and was asked to review in the next cycle.
• Next menstrual cycle – Defaulters with inadequate
follicular development in previous cycle were once again
treated with same regimen. In the absence of menstruation,
diagnosis of pregnancy was confirmed by either urine
pregnancy test/ bimanual examination/ TVS. But if not found
to be pregnant, progesterone induced withdrawal bleeding
was given and same regimen was given. Treatment was given
for a maximum of 3 cycles.
• Main outcomes measured were number of follicles,
endometrial thickness, ovulation rate, pregnancy rate and
• Statistical Analysis were reported as mean (SD) for
continuous variables, frequencies (percentage) for categorical
variables. Data were statistically evaluated with IBM SPSS
Statistics for Windows, Version 20.0, IBM Corp, Chicago, IL.
The patients who underwent treatment as per our study
protocol were analysed statistically with student ‘t’ test and chi
square test and the results were tabulated.
The majority of patients in Group CC and Group CC-NAC were
in the age group of 21-25 years. Minimum age was 18 years and
maximum age was 36 years. This shows that anovulation was
found to be more common between the age of 21-25 years which
is the period of maximum fecundity (Table 1).
Out of 117 cases, Laparoscopy were done in 38 cases (32.47%)
and anovulatory ovaries were seen in 17 cases (44.73%) in
group CC and 21 cases (55.26%) in group CC-NAC. In another
79 cases(67.52%), sonosalphingography was done in 48 cases
(60.75%) [Group CC- 25 (52.08%), Group CC-NAC- 23 (47.91%)]
and HSG in 31 cases (39.24%) [Group CC-15 (48.38%), Group CCNAC-
In group CC (n=61), a total of 55 cases ovulated, 19 cases
conceived, 6 cases had miscarriage and 4 cases has multiple
pregnancies. In group CC-NAC (n=56), a total of 54 cases ovulated,
39 cases conceived, 5 cases had miscarriage and 2 cases has
multiple pregnancies. There is a significant statistical difference
(p<0.001) in the outcome rate in terms of live birth which was
found higher 37 cases (94.87%) in group CC-NAC 37 while
comparing with 15 cases (78.94%) in group CC (Table 5) (Graph
The Spearman’s Rank correlation analysis were done which
show highly positive correlation (ρ=0.8) between clomiphene
citrate – N-acetyl cysteine and number of pregnancies and weak
correlation (ρ<0.1) between clomiphene citrate and number
of pregnancies in our study. The outcome in terms of number
of pregnancies between Group CC and Group CC-NAC were
statistically significant (p<0.01) (Graph 3).
Anovulatory infertility is classified according to WHO into 3
categories out of which category 1 and 2 is amenable to treatment
with ovulation induction. Clomiphene citrate , traditionally
has been the gold standard drug for ovulation induction. It is a
non-steroidal triphenylethylene derivative with both estrogen
agonist and antagonist properties. Due to its structural similarity
to estrogen, clomiphene competes for and binds nuclear estrogen
receptors throughout the reproductive system. It acts centrally by
reducing estrogen negative feedback and consequent increased
pituitary gonadotropin release which in turn drives ovarian
follicular development and ovulation. However, as a singular drug
it is not equally effective in all situations. It has variable success
rates in anovulatory women, lower especially in those with PCOS
with insulin resistance. Majority (80%) of cases of anovulatory
infertility are due to PCOS , thus making insulin resistance and
hyperinsulinemia prevalence very high among cases .
Others causes being stress related, Sheehan’s syndrome,
anorexia nervosa, Kallmann’s syndrome, etc. ; but in our study
all cases of anovulatory infertility has been taken into account and
further categorization into the specific causes for the same has not
N-acetyl cysteine, acetylated precursor of L-cysteine and
reduced glutathione , is a commonly used mucolytic drug.
Due to its multiplicity of action, it is the most desirable adjuvant
to augment ovulation induction. It softens the tenacious cervical
mucous secretions and overcomes the peripheral antiestrogenic
hostile effect of clomiphene  and thus has a higher pregnancy
rates if combination regimen (clomiphene + NAC) is used . The
antiapoptotic effects of NAC  are responsible for significantly
higher number of follicles as it is well known that apoptosis is
the main mechanism involved in follicular cohort atresia. NAC
was found to inhibit apoptosis in cultured ovarian primordial
germ cells . NAC causes insulin secretion in pancreatic cells
and regulates insulin receptors in human erythrocytes. Thus,
has a proven insulin sensitizing action [13,4]. Furthermore, it
is a powerful antioxidant and a potential therapeutic agent in
the treatment of diseases characterized by generation of free
oxygen radicals . The biological activity of NAC is attributed
to its sulfhydryl group which enhances glutathione -S-transferase
activity aiding in the protection of all cells and membranes .
Various studies done in the past decades have shown promising
results with additional usage of NAC along with the standard
clomiphene citrate for ovulation induction. In 2005, an RCT on
150 women with PCOS (4) showed that endometrial thickness
was more in the group CC-NAC (5.9± 0.7mm) as compared to CCplacebo
(4.9 ± 1.9mm); (p>0.05) but was statistically insignificant.
Ovulation and pregnancy rate were higher with NAC (49.3%;
21.3%) than in the control group (1.3%; 0%), p<0.0001which was
statistically significant. 5 cases of multiple pregnancies, 2 cases of
miscarriages (12.5%) (1 singleton and 1 multiple pregnancy) and
no cases of OHSS were reported in NAC group. In 2012, Salehpour
et al.  concluded that the number of follicles >18mm, mean
endometrial thickness, ovulation and pregnancy rate were
significantly higher among CC-NAC group (p=0.001, p=0.02 &
0.04 respectively). No adverse side-effects and no cases of ovarian
hyperstimulation were observed in group receiving NAC. A metaanalysis
conducted by Thakker et al. , where 8 RCT with 910
women with PCOS effects of NAC were compared with placebo/
metformin. NAC significantly improved rates of live births and
spontaneous ovulation compared to placebo. However, it was
not associated with greater benefits to metformin for improving
pregnancy rate, spontaneous ovulation and menstrual regularity.
Maged AM et al. , in an RCT in 2015 showed that NAC as an
adjuvant to clomiphene improves ovulation and pregnancy rates
in PCOS patients with beneficial impacts on endometrial thickness
as compared to the both groups (CC alone and CC with metformin)
On the other hand, in the recent RCT on 97 PCOS women
in 2017, results showed no significant differences in the study
group (NAC +CC+ Letrozole) vs (CC + Letrozole) regarding mean
endometrial thickness (p=0.14), mean number of mature follicles
(p=0.20), and pregnancy rate (p=0.09) . This was in contrast
to the findings of our study which highlights the effectiveness of
NAC. However, all these previous studies have been exclusively
done on women with PCOS which is a subset of all the various
cases of anovulatory infertility. Thus, data proving effectiveness of
NAC in all cases of anovulation is scarce and our study throws light
in this direction.
Endometrial thickness, which is the maximum distance
between the echogenic interfaces of the myometrium and the
endometrium measured in a pane through central longitudinal
axis; was found to be higher in CC-NAC group (12.19 ± 1.36mm) as
compared to CC group (10.17 ± 1.01mm). Ovulation and conception
rate were also higher in CC-NAC group (96.42%;72.22%) than with
CC group (90.16%; 34.54%). Clinical pregnancy rate was 94.87%
in the combination group which was statistically higher than in CC
group (78.94%); p< <0.001. More monofollicular stimulation and
thus lesser cases of multiple pregnancy (12.82%) was in CC-NAC
group than in CC group (31.57%). Miscarriage rates were higher
in CC group (21.05%) as compared to CC-NAC group (5.12%).
However, our study was limited to 3 treatment cycles. No cases
of ovarian hyperstimulation were reported. N-acetyl cysteine was
well tolerated by all patients and no adverse effects were observed.
N-acetyl cysteine may be a novel adjuvant to clomiphene
citrate in inducing or augmenting ovulation. It is simple, well tolerated and inexpensive agent. The route of administration
is simple (oral) and monitoring of patients is by non-invasive
method (TVS). It could be used as an alternative to other insulinsensitizing
agents like metformin.