WARNINGS
Included as part of the PRECAUTIONS section.
PRECAUTIONS
Myopathy/Rhabdomyolysis
Simvastatin occasionally causes myopathy manifested as
muscle pain, tenderness or weakness with creatine kinase (CK) above ten times
the upper limit of normal (ULN). Myopathy sometimes takes the form of
rhabdomyolysis with or without acute renal failure secondary to myoglobinuria,
and rare fatalities have occurred. The risk of myopathy is increased by
elevated plasma levels of simvastatin and simvastatin acid. Predisposing
factors for myopathy include advanced age (≥65 years), female gender,
uncontrolled hypothyroidism, and renal impairment.
The risk of myopathy, including rhabdomyolysis, is
dose related. In a clinical trial database in which 41,413 patients were
treated with ZOCOR, 24,747 (approximately 60%) of whom were enrolled in studies
with a median follow-up of at least 4 years, the incidence of myopathy was
approximately 0.03% and 0.08% at 20 and 40 mg/day, respectively. The incidence
of myopathy with 80 mg (0.61%) was disproportionately higher than that observed
at the lower doses. In these trials, patients were carefully monitored and some
interacting medicinal products were excluded.
In a clinical trial in which 12,064 patients with a
history of myocardial infarction were treated with ZOCOR (mean follow-up 6.7
years), the incidence of myopathy (defined as unexplained muscle weakness or
pain with a serum creatine kinase [CK] >10 times upper limit of normal
[ULN]) in patients on 80 mg/day was approximately 0.9% compared with 0.02% for
patients on 20 mg/day. The incidence of rhabdomyolysis (defined as myopathy
with a CK >40 times ULN) in patients on 80 mg/day was approximately 0.4%
compared with 0% for patients on 20 mg/day. The incidence of myopathy,
including rhabdomyolysis, was highest during the first year and then notably
decreased during the subsequent years of treatment. In this trial, patients
were carefully monitored and some interacting medicinal products were excluded.
The risk of myopathy, including rhabdomyolysis, is
greater in patients on simvastatin 80 mg compared with other statin therapies
with similar or greater LDL-C-lowering efficacy and compared with lower doses
of simvastatin. Therefore, the 80-mg dose of ZOCOR should be used only in
patients who have been taking simvastatin 80 mg chronically (e.g., for 12
months or more) without evidence of muscle toxicity [see DOSAGE AND
ADMINISTRATION, Restricted Dosing for 80 mg]. If, however, a patient who is
currently tolerating the 80-mg dose of ZOCOR needs to be initiated on an
interacting drug that is contraindicated or is associated with a dose cap for
simvastatin, that patient should be switched to an alternative statin with less
potential for the drug-drug interaction. Patients should be advised of the
increased risk of myopathy, including rhabdomyolysis, and to report promptly any
unexplained muscle pain, tenderness or weakness. If symptoms occur, treatment
should be discontinued immediately. [See Liver Dysfunction]
There have been rare reports of immune-mediated
necrotizing myopathy (IMNM), an autoimmune myopathy, associated with statin
use. IMNM is characterized by: proximal muscle weakness and elevated serum
creatine kinase, which persist despite discontinuation of statin treatment;
muscle biopsy showing necrotizing myopathy without significant inflammation;
improvement with immunosuppressive agents.
All patients starting therapy with ZOCOR, or whose
dose of ZOCOR is being increased, should be advised of the risk of myopathy,
including rhabdomyolysis, and told to report promptly any unexplained muscle
pain, tenderness or weakness particularly if accompanied by malaise or fever or
if muscle signs and symptoms persist after discontinuing ZOCOR. ZOCOR therapy
should be discontinued immediately if myopathy is diagnosed or suspected. In
most cases, muscle symptoms and CK increases resolved when treatment was
promptly discontinued. Periodic CK determinations may be considered in
patients starting therapy with ZOCOR or whose dose is being increased, but
there is no assurance that such monitoring will prevent myopathy.
Many of the patients who have developed rhabdomyolysis on
therapy with simvastatin have had complicated medical histories, including
renal insufficiency usually as a consequence of long-standing diabetes
mellitus. Such patients merit closer monitoring. ZOCOR therapy should be
discontinued if markedly elevated CPK levels occur or myopathy is diagnosed or
suspected. ZOCOR therapy should also be temporarily withheld in any patient
experiencing an acute or serious condition predisposing to the development of
renal failure secondary to rhabdomyolysis, e.g., sepsis; hypotension; major
surgery; trauma; severe metabolic, endocrine, or electrolyte disorders; or
uncontrolled epilepsy.
Drug Interactions
The risk of myopathy and rhabdomyolysis is increased by
elevated plasma levels of simvastatin and simvastatin acid. Simvastatin is
metabolized by the cytochrome P450 isoform 3A4. Certain drugs which inhibit
this metabolic pathway can raise the plasma levels of simvastatin and may
increase the risk of myopathy. These include itraconazole, ketoconazole,
posaconazole, voriconazole, the macrolide antibiotics erythromycin and
clarithromycin, and the ketolide antibiotic telithromycin, HIV protease
inhibitors, boceprevir, telaprevir, the antidepressant nefazodone,
cobicistat-containing products, or grapefruit juice [see CLINICAL
PHARMACOLOGY]. Combination of these drugs with simvastatin is
contraindicated. If short-term treatment with strong CYP3A4 inhibitors is
unavoidable, therapy with simvastatin must be suspended during the course of
treatment. [See CONTRAINDICATIONS and DRUG INTERACTIONS]
The combined use of simvastatin with gemfibrozil,
cyclosporine, or danazol is contraindicated [see CONTRAINDICATIONS and DRUG
INTERACTIONS].
Caution should be used when prescribing other fibrates
with simvastatin, as these agents can cause myopathy when given alone and the
risk is increased when they are coadministered [see DRUG INTERACTIONS].
Cases of myopathy, including rhabdomyolysis, have been
reported with simvastatin coadministered with colchicine, and caution should be
exercised when prescribing simvastatin with colchicine [see DRUG
INTERACTIONS].
The benefits of the combined use of simvastatin with the
following drugs should be carefully weighed against the potential risks of
combinations: other lipid-lowering drugs (other fibrates, ≥1 g/day of
niacin, or, for patients with HoFH, lomitapide), amiodarone, dronedarone,
verapamil, diltiazem, amlodipine, or ranolazine [see DRUG INTERACTIONS and
Table 3 in CLINICAL PHARMACOLOGY] [also see DOSAGE AND ADMINISTRATION,
Patients with Homozygous Familial Hypercholesterolemia].
Cases of myopathy, including rhabdomyolysis, have been
observed with simvastatin coadministered with lipid-modifying doses (≥1
g/day niacin) of niacin-containing products. In an ongoing, double-blind,
randomized cardiovascular outcomes trial, an independent safety monitoring
committee identified that the incidence of myopathy is higher in Chinese
compared with non-Chinese patients taking simvastatin 40 mg coadministered with
lipid-modifying doses of a niacin-containing product. Caution should be used
when treating Chinese patients with simvastatin in doses exceeding 20 mg/day
coadministered with lipid-modifying doses of niacin-containing products.
Because the risk for myopathy is dose-related, Chinese patients should not
receive simvastatin 80 mg coadministered with lipid-modifying doses of
niacin-containing products. It is unknown if the risk for myopathy with
coadministration of simvastatin with lipid-modifying doses of niacin-containing
products observed in Chinese patients applies to other Asian patients [see
DRUG INTERACTIONS].
Prescribing recommendations for interacting agents are
summarized in Table 1 [see also DOSAGE AND ADMINISTRATION, DRUG
INTERACTIONS, CLINICAL PHARMACOLOGY].
Table 1: Drug Interactions Associated with Increased
Risk of Myopathy/Rhabdomyolysis
Interacting Agents |
Prescribing Recommendations |
Strong CYP3A4 Inhibitors, e.g.: |
|
Itraconazole
Ketoconazole
Posaconazole
Voriconazole
Erythromycin
Clarithromycin
Telithromycin
HIV protease inhibitors
Boceprevir
Telaprevir
Nefazodone
Cobicistat-containing products
Gemfibrozil
Cyclosporine
Danazol |
Contraindicated with simvastatin |
Verapamil
Diltiazem
Dronedarone |
Do not exceed 10 mg simvastatindaily |
Amiodarone
Amlodipine
Ranolazine |
Do not exceed 20 mg simvastatin
daily |
Lomitapide |
For patients with HoFH, do not exceed 20 mg simvastatin daily* |
Grapefruit juice |
Avoid grapefruit juice |
* For patients with HoFH who
have been taking 80 mg simvastatin chronically (e.g., for 12 months or more)
without evidence of muscle toxicity, do not exceed 40 mg simvastatin when
taking lomitapide. |
Liver Dysfunction
Persistent increases (to
more than 3X the ULN) in serum transaminases have occurred in approximately 1%
of patients who received simvastatin in clinical studies . When drug treatment
was interrupted or discontinued in these patients, the transaminase levels
usually fell slowly to pretreatment levels. The increases were not associated
with jaundice or other clinical signs or symptoms. There was no evidence of
hypersensitivity.
In the Scandinavian Simvastatin
Survival Study (4S) [see Clinical Studies], the number of patients with
more than one transaminase elevation to >3X ULN, over the course of the
study, was not significantly different between the simvastatin and placebo
groups (14 [0.7%] vs. 12 [0.6%]). Elevated transaminases resulted in the
discontinuation of 8 patients from therapy in the simvastatin group (n=2,221)
and 5 in the placebo group (n=2,223). Of the 1,986 simvastatin treated patients
in 4S with normal liver function tests (LFTs) at baseline, 8 (0.4%) developed
consecutive LFT elevations to >3X ULN and/or were discontinued due to
transaminase elevations during the 5.4 years (median follow-up) of the study.
Among these 8 patients, 5 initially developed these abnormalities within the
first year. All of the patients in this study received a starting dose of 20 mg
of simvastatin; 37% were titrated to 40 mg.
In 2 controlled clinical
studies in 1,105 patients, the 12-month incidence of persistent hepatic
transaminase elevation without regard to drug relationship was 0.9% and 2.1% at
the 40- and 80-mg dose, respectively. No patients developed persistent liver
function abnormalities following the initial 6 months of treatment at a given
dose.
It is recommended that liver
function tests be performed before the initiation of treatment, and thereafter
when clinically indicated. There have been rare postmarketing reports of fatal and
non-fatal hepatic failure in patients taking statins, including simvastatin. If
serious liver injury with clinical symptoms and/or hyperbilirubinemia or
jaundice occurs during treatment with ZOCOR, promptly interrupt therapy. If an
alternate etiology is not found do not restart ZOCOR. Note that ALT may emanate
from muscle, therefore ALT rising with CK may indicate myopathy [see Myopathy/Rhabdomyolysis].
The drug should be used with caution in patients who
consume substantial quantities of alcohol and/or have a past history of liver
disease. Active liver diseases or unexplained transaminase elevations are
contraindications to the use of simvastatin.
Moderate (less than 3X ULN) elevations of serum
transaminases have been reported following therapy with simvastatin. These
changes appeared soon after initiation of therapy with simvastatin, were often
transient, were not accompanied by any symptoms and did not require
interruption of treatment.
Endocrine Function
Increases in HbA1c and fasting serum glucose levels have
been reported with HMG-CoA reductase inhibitors, including ZOCOR.
Nonclinical Toxicology
Carcinogenesis, Mutagenesis,
Impairment Of Fertility
In a 72-week carcinogenicity
study, mice were administered daily doses of simvastatin of 25, 100, and 400
mg/kg body weight, which resulted in mean plasma drug levels approximately 1,
4, and 8 times higher than the mean human plasma drug level, respectively (as
total inhibitory activity based on AUC) after an 80-mg oral dose. Liver
carcinomas were significantly increased in high-dose females and mid- and
high-dose males with a maximum incidence of 90% in males. The incidence of
adenomas of the liver was significantly increased in mid- and high-dose
females. Drug treatment also significantly increased the incidence of lung
adenomas in mid- and high-dose males and females. Adenomas of the Harderian
gland (a gland of the eye of rodents) were significantly higher in high-dose
mice than in controls. No evidence of a tumorigenic effect was observed at 25
mg/kg/day.
In a separate 92-week
carcinogenicity study in mice at doses up to 25 mg/kg/day, no evidence of a
tumorigenic effect was observed (mean plasma drug levels were 1 times higher
than humans given 80 mg simvastatin as measured by AUC).
In a two-year study in rats at
25 mg/kg/day, there was a statistically significant increase in the incidence
of thyroid follicular adenomas in female rats exposed to approximately 11 times
higher levels of simvastatin than in humans given 80 mg simvastatin (as
measured by AUC).
A second two-year rat
carcinogenicity study with doses of 50 and 100 mg/kg/day produced hepatocellular
adenomas and carcinomas (in female rats at both doses and in males at 100
mg/kg/day). Thyroid follicular cell adenomas were increased in males and
females at both doses; thyroid follicular cell carcinomas were increased in
females at 100 mg/kg/day. The increased incidence of thyroid neoplasms appears
to be consistent with findings from other statins. These treatment levels
represented plasma drug levels (AUC) of approximately 7 and 15 times (males)
and 22 and 25 times (females) the mean human plasma drug exposure after an 80
milligram daily dose.
No evidence of mutagenicity was
observed in a microbial mutagenicity (Ames) test with or without rat or mouse
liver metabolic activation. In addition, no evidence of damage to genetic
material was noted in an in vitro alkaline elution assay using rat hepatocytes,
a V-79 mammalian cell forward mutation study, an in vitro chromosome aberration
study in CHO cells, or an in vivo chromosomal aberration assay in mouse bone
marrow.
There was decreased fertility
in male rats treated with simvastatin for 34 weeks at 25 mg/kg body weight (4
times the maximum human exposure level, based on AUC, in patients receiving 80
mg/day); however, this effect was not observed during a subsequent fertility
study in which simvastatin was administered at this same dose level to male
rats for 11 weeks (the entire cycle of spermatogenesis including epididymal
maturation). No microscopic changes were observed in the testes of rats from
either study. At 180 mg/kg/day, (which produces exposure levels 22 times higher
than those in humans taking 80 mg/day based on surface area, mg/m²),
seminiferous tubule degeneration (necrosis and loss of spermatogenic
epithelium) was observed. In dogs, there was drug-related testicular atrophy,
decreased spermatogenesis, spermatocytic degeneration and giant cell formation
at 10 mg/kg/day, (approximately 2 times the human exposure, based on AUC, at 80
mg/day). The clinical significance of these findings is unclear.
Use In Specific Populations
Pregnancy
Pregnancy Category X [See CONTRAINDICATIONS]
ZOCOR is contraindicated in women who are or may become
pregnant. Lipid lowering drugs offer no benefit during pregnancy, because
cholesterol and cholesterol derivatives are needed for normal fetal
development. Atherosclerosis is a chronic process, and discontinuation of
lipid-lowering drugs during pregnancy should have little impact on long-term
outcomes of primary hypercholesterolemia therapy. There are no adequate and
well-controlled studies of use with ZOCOR during pregnancy; however, there are
rare reports of congenital anomalies in infants exposed to statins in utero.
Animal reproduction studies of simvastatin in rats and rabbits showed no
evidence of teratogenicity. Serum cholesterol and triglycerides increase during
normal pregnancy, and cholesterol or cholesterol derivatives are essential for
fetal development. Because statins decrease cholesterol synthesis and possibly
the synthesis of other biologically active substances derived from cholesterol,
ZOCOR may cause fetal harm when administered to a pregnant woman. If ZOCOR is
used during pregnancy or if the patient becomes pregnant while taking this
drug, the patient should be apprised of the potential hazard to the fetus.
There are rare reports of congenital anomalies following
intrauterine exposure to statins. In a review2 of approximately 100
prospectively followed pregnancies in women exposed to simvastatin or another
structurally related statin, the incidences of congenital anomalies,
spontaneous abortions, and fetal deaths/stillbirths did not exceed those
expected in the general population. However, the study was only able to exclude
a 3- to 4-fold increased risk of congenital anomalies over the background rate.
In 89% of these cases, drug treatment was initiated prior to pregnancy and was
discontinued during the first trimester when pregnancy was identified.
Simvastatin was not teratogenic in rats or rabbits at
doses (25, 10 mg/kg/day, respectively) that resulted in 3 times the human
exposure based on mg/m² surface area. However, in studies with another
structurally-related statin, skeletal malformations were observed in rats and
mice.
Women of childbearing potential, who require treatment
with ZOCOR for a lipid disorder, should be advised to use effective
contraception. For women trying to conceive, discontinuation of ZOCOR should be
considered. If pregnancy occurs, ZOCOR should be immediately discontinued.
Nursing Mothers
It is not known whether simvastatin is excreted in human
milk. Because a small amount of another drug in this class is excreted in human
milk and because of the potential for serious adverse reactions in nursing
infants, women taking simvastatin should not nurse their infants. A decision
should be made whether to discontinue nursing or discontinue drug, taking into
account the importance of the drug to the mother [see CONTRAINDICATIONS].
Pediatric Use
Safety and effectiveness of simvastatin in patients 10-17
years of age with heterozygous familial hypercholesterolemia have been
evaluated in a controlled clinical trial in adolescent boys and in girls who
were at least 1 year post-menarche. Patients treated with simvastatin had an
adverse reaction profile similar to that of patients treated with placebo. Doses
greater than 40 mg have not been studied in this population. In this
limited controlled study, there was no significant effect on growth or sexual
maturation in the adolescent boys or girls, or on menstrual cycle length in
girls. [See DOSAGE AND ADMINISTRATION, ADVERSE REACTIONS, Clinical
Studies] Adolescent females should be counseled on appropriate
contraceptive methods while on simvastatin therapy [see CONTRAINDICATIONS
and Use In Specific Populations]. Simvastatin has not been studied in
patients younger than 10 years of age, nor in pre-menarchal girls.
Geriatric Use
Of the 2,423 patients who received ZOCOR in Phase III
clinical studies and the 10,269 patients in the Heart Protection Study who
received ZOCOR, 363 (15%) and 5,366 (52%), respectively were ≥65 years
old. In HPS, 615 (6%) were ≥75 years old. No overall differences in
safety or effectiveness were observed between these subjects and younger subjects,
and other reported clinical experience has not identified differences in
responses between the elderly and younger patients, but greater sensitivity of
some older individuals cannot be ruled out. Since advanced age (≥65
years) is a predisposing factor for myopathy, ZOCOR should be prescribed with
caution in the elderly. [See CLINICAL PHARMACOLOGY]
A pharmacokinetic study with simvastatin showed the mean
plasma level of statin activity to be approximately 45% higher in elderly
patients between 70-78 years of age compared with patients between 18-30 years
of age. In 4S, 1,021 (23%) of 4,444 patients were 65 or older. Lipid-lowering
efficacy was at least as great in elderly patients compared with younger
patients, and ZOCOR significantly reduced total mortality and CHD mortality in
elderly patients with a history of CHD. In HPS, 52% of patients were elderly
(4,891 patients 65-69 years and 5,806 patients 70 years or older). The relative
risk reductions of CHD death, non-fatal MI, coronary and non-coronary revascularization
procedures, and stroke were similar in older and younger patients [see Clinical
Studies]. In HPS, among 32,145 patients entering the active run-in period,
there were 2 cases of myopathy/rhabdomyolysis; these patients were aged 67 and
73. Of the 7 cases of myopathy/rhabdomyolysis among 10,269 patients allocated
to simvastatin, 4 were aged 65 or more (at  baseline), of whom one was over 75.
There were no overall differences in safety between older and younger patients
in either 4S or HPS.
Because advanced age (≥65 years) is a predisposing
factor for myopathy, including rhabdomyolysis, ZOCOR should be prescribed with
caution in the elderly. In a clinical trial of patients treated with
simvastatin 80 mg/day, patients ≥65 years of age had an increased risk of
myopathy, including rhabdomyolysis, compared to patients <65 years of age. [See
WARNINGS AND PRECAUTIONS and CLINICAL PHARMACOLOGY]
Renal Impairment
Caution should be exercised when ZOCOR is administered to
patients with severe renal impairment. [See DOSAGE AND ADMINISTRATION]
Hepatic Impairment
ZOCOR is contraindicated in patients with active liver
disease which may include unexplained persistent elevations in hepatic
transaminase levels [see CONTRAINDICATIONS and WARNINGS AND
PRECAUTIONS].
REFERENCE
2 Manson, J.M., Freyssinges, C., Ducrocq,
M.B., Stephenson, W.P., Postmarketing Surveillance of Lovastatin and
Simvastatin Exposure During Pregnancy, Reproductive Toxicology, 10(6):439-446,
1996.