WARNINGS
Included as part of the "PRECAUTIONS" Section
PRECAUTIONS
Fetal Toxicity
Use of drugs that act on the renin-angiotensin system during the second and third trimesters of
pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting
oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential
neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When
pregnancy is detected, discontinue HYZAAR as soon as possible.
Thiazides cross the placental barrier and appear in cord blood. Adverse reactions include fetal or
neonatal jaundice, thrombocytopenia [see Use In Specific Populations].
Hypotension In Volume- Or Salt-Depleted Patients
In patients with an activated renin-angiotensin system, such as volume- or salt-depleted patients (e.g.,
those being treated with high doses of diuretics), symptomatic hypotension may occur after initiation of
treatment with HYZAAR. Correct volume or salt depletion prior to administration of HYZAAR. Do not use
HYZAAR as initial therapy in patients with intravascular volume depletion.
Impaired Renal Function
Changes in renal function including acute renal failure can be caused by drugs that inhibit the reninangiotensin
system and by diuretics. Patients whose renal function may depend in part on the activity of
the renin-angiotensin system (e.g., patients with renal artery stenosis, chronic kidney disease, severe
congestive heart failure, or volume depletion) may be at particular risk of developing acute renal failure on
HYZAAR. Monitor renal function periodically in these patients. Consider withholding or discontinuing
therapy in patients who develop a clinically significant decrease in renal function on HYZAAR [see DRUG INTERACTIONS and Use In Specific Populations].
Hypersensitivity
Hypersensitivity reactions to hydrochlorothiazide may occur in patients with or without a history of allergy
or bronchial asthma, but are more likely in patients with such a history.
Electrolyte And Metabolic Effects
In double-blind clinical trials of various doses of losartan potassium and hydrochlorothiazide, the
incidence of hypertensive patients who developed hypokalemia (serum potassium <3.5 mEq/L) was 6.7%
versus 3.5% for placebo; the incidence of hyperkalemia (serum potassium >5.7 mEq/L) was 0.4% versus
0% for placebo.
HYZAAR contains hydrochlorothiazide which can cause hypokalemia, hyponatremia and
hypomagnesemia. Hypomagnesemia can result in hypokalemia which may be difficult to treat despite
potassium repletion. HYZAAR also contains losartan which can cause hyperkalemia. Monitor serum
electrolytes periodically [see DRUG INTERACTIONS].
Concomitant use of other drugs that may increase serum potassium may lead to hyperkalemia [see DRUG INTERACTIONS].
Hydrochlorothiazide may alter glucose tolerance and raise serum levels of cholesterol and triglycerides.
Hyperuricemia may occur or frank gout may be precipitated in patients receiving thiazide therapy.
Because losartan decreases uric acid, losartan in combination with hydrochlorothiazide attenuates the
diuretic-induced hyperuricemia.
Hydrochlorothiazide decreases urinary calcium excretion and may cause elevations of serum calcium.
Monitor calcium levels.
Acute Myopia And Secondary Angle-Closure Glaucoma
Hydrochlorothiazide, a sulfonamide, can cause an idiosyncratic reaction, resulting in acute transient
myopia and acute angle-closure glaucoma. Symptoms include acute onset of decreased visual acuity or
ocular pain and typically occur within hours to weeks of drug initiation. Untreated acute angle-closure
glaucoma can lead to permanent vision loss. The primary treatment is to discontinue hydrochlorothiazide
as rapidly as possible. Prompt medical or surgical treatments may need to be considered if the intraocular
pressure remains uncontrolled. Risk factors for developing acute angle-closure glaucoma may include a
history of sulfonamide or penicillin allergy.
Systemic Lupus Erythematosus
Thiazide diuretics have been reported to cause exacerbation or activation of systemic lupus
erythematosus.
Postsympathectomy Patients
The antihypertensive effects of the drug may be enhanced in the postsympathectomy patient.
Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (PATIENT INFORMATION).
Pregnancy
Advise female patients of childbearing age about the consequences of exposure to HYZAAR
during pregnancy. Discuss treatment options with women planning to become pregnant. Tell patients to
report pregnancies to their physicians as soon as possible [see WARNINGS AND PRECAUTIONS and Use In Specific Populations].
Symptomatic Hypotension
Advise patients that lightheadedness can occur, especially during the first
days of therapy, and to report this symptom to a healthcare provider. Inform patients that dehydration
from inadequate fluid intake, excessive perspiration, vomiting, or diarrhea may lead to an excessive fall in
blood pressure. If syncope occurs, advise patients to contact their healthcare provider [see WARNINGS AND PRECAUTIONS].
Potassium Supplements
Advise patients not to use potassium supplements or salt substitutes containing
potassium without consulting their healthcare provider [see DRUG INTERACTIONS].
Acute Myopia And Secondary Angle-Closure Glaucoma
Advise patients to discontinue HYZAAR and seek
immediate medical attention if they experience symptoms of Acute Myopia or Secondary Angle-Closure
Glaucoma [see WARNINGS AND PRECAUTIONS ].
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Losartan Potassium-Hydrochlorothiazide
No carcinogenicity studies have been conducted with the losartan potassium-hydrochlorothiazide
combination.
Losartan potassium-hydrochlorothiazide when tested at a weight ratio of 4:1, was negative in the Ames
microbial mutagenesis assay and the V-79 Chinese hamster lung cell mutagenesis assay. In addition,
there was no evidence of direct genotoxicity in the in vitro alkaline elution assay in rat hepatocytes and
in vitro chromosomal aberration assay in Chinese hamster ovary cells at noncytotoxic concentrations.
Losartan potassium, coadministered with hydrochlorothiazide, had no effect on the fertility or mating
behavior of male rats at dosages up to 135 mg/kg/day of losartan and 33.75 mg/kg/day of
hydrochlorothiazide. These dosages have been shown to provide respective systemic exposures (AUCs)
for losartan, its active metabolite and hydrochlorothiazide that are approximately 60, 60 and 30 times
greater than those achieved in humans with 100 mg of losartan potassium in combination with 25 mg of
hydrochlorothiazide. In female rats, however, the coadministration of doses as low as 10 mg/kg/day of
losartan and 2.5 mg/kg/day of hydrochlorothiazide was associated with slight but statistically significant
decreases in fecundity and fertility indices. AUC values for losartan, its active metabolite and
hydrochlorothiazide, extrapolated from data obtained with losartan administered to rats at a dose of
50 mg/kg/day in combination with 12.5 mg/kg/day of hydrochlorothiazide, were approximately 6, 2, and
2 times greater than those achieved in humans with 100 mg of losartan in combination with 25 mg of
hydrochlorothiazide.
Losartan Potassium
Losartan potassium was not carcinogenic when administered at maximally tolerated dosages to rats and
mice for 105 and 92 weeks, respectively. Female rats given the highest dose (270 mg/kg/day) had a
slightly higher incidence of pancreatic acinar adenoma. The maximally tolerated dosages (270 mg/kg/day
in rats, 200 mg/kg/day in mice) provided systemic exposures for losartan and its pharmacologically active
metabolite that were approximately 160 and 90 times (rats) and 30 and 15 times (mice) the exposure of a
50 kg human given 100 mg per day.
Losartan potassium was negative in the microbial mutagenesis and V-79 mammalian cell mutagenesis
assays and in the in vitro alkaline elution and in vitro and in vivo chromosomal aberration assays. In
addition, the active metabolite showed no evidence of genotoxicity in the microbial mutagenesis, in vitro alkaline elution, and in vitro chromosomal aberration assays.
Fertility and reproductive performance were not affected in studies with male rats given oral doses of
losartan potassium up to approximately 150 mg/kg/day. The administration of toxic dosage levels in
females (300/200 mg/kg/day) was associated with a significant (p<0.05) decrease in the number of
corpora lutea/female, implants/female, and live fetuses/female at C-section. At 100 mg/kg/day only a
decrease in the number of corpora lutea/female was observed. The relationship of these findings to drugtreatment
is uncertain since there was no effect at these dosage levels on implants/pregnant female,
percent post-implantation loss, or live animals/litter at parturition. In nonpregnant rats dosed at
135 mg/kg/day for 7 days, systemic exposure (AUCs) for losartan and its active metabolite were
approximately 66 and 26 times the exposure achieved in man at the maximum recommended human
daily dosage (100 mg).
Hydrochlorothiazide
Two-year feeding studies in mice and rats conducted under the auspices of the National Toxicology
Program (NTP) uncovered no evidence of a carcinogenic potential of hydrochlorothiazide in female mice
(at doses of up to approximately 600 mg/kg/day) or in male and female rats (at doses of up to
approximately 100 mg/kg/day). The NTP, however, found equivocal evidence for hepatocarcinogenicity in
male mice.
Hydrochlorothiazide was not genotoxic in vitro in the Ames mutagenicity assay of Salmonella typhimurium
strains TA 98, TA 100, TA 1535, TA 1537, and TA 1538 and in the Chinese Hamster Ovary (CHO) test for
chromosomal aberrations, or in vivo in assays using mouse germinal cell chromosomes, Chinese hamster
bone marrow chromosomes, and the Drosophila sex-linked recessive lethal trait gene. Positive test
results were obtained only in the in vitro CHO Sister Chromatid Exchange (clastogenicity) and in the
Mouse Lymphoma Cell (mutagenicity) assays, using concentrations of hydrochlorothiazide from 43 to
1300 mcg/mL, and in the Aspergillus nidulans non-disjunction assay at an unspecified concentration.
Hydrochlorothiazide had no adverse effects on the fertility of mice and rats of either sex in studies
wherein these species were exposed, via their diet, to doses of up to 100 and 4 mg/kg, respectively, prior
to mating and throughout gestation.
Use In Specific Populations
Pregnancy
Pregnancy Category D
Use of drugs that act on the renin-angiotensin system during the second and third trimesters of
pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting
oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential
neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When
pregnancy is detected, discontinue losartan as soon as possible. These adverse outcomes are usually
associated with use of these drugs in the second and third trimester of pregnancy. Most epidemiologic
studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not
distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents.
Appropriate management of maternal hypertension during pregnancy is important to optimize outcomes
for both mother and fetus.
In the unusual case that there is no appropriate alternative to therapy with drugs affecting the reninangiotensin
system for a particular patient, apprise the mother of the potential risk to the fetus. Perform
serial ultrasound examinations to assess the intra-amniotic environment. If oligohydramnios is observed,
discontinue HYZAAR, unless it is considered lifesaving for the mother. Fetal testing may be appropriate,
based on the week of pregnancy. Patients and physicians should be aware, however, that
oligohydramnios may not appear until after the fetus has sustained irreversible injury. Closely observe
infants with histories of in utero exposure to HYZAAR for hypotension, oliguria, and hyperkalemia [see Pediatric Use].
There was no evidence of teratogenicity in rats or rabbits treated with a maximum losartan potassium
dose of 10 mg/kg/day in combination with 2.5 mg/kg/day of hydrochlorothiazide. At these dosages,
respective exposures (AUCs) of losartan, its active metabolite, and hydrochlorothiazide in rabbits were
approximately 5, 1.5, and 1.0 times those achieved in humans with 100 mg losartan in combination with
25 mg hydrochlorothiazide. AUC values for losartan, its active metabolite and hydrochlorothiazide,
extrapolated from data obtained with losartan administered to rats at a dose of 50 mg/kg/day in
combination with 12.5 mg/kg/day of hydrochlorothiazide, were approximately 6, 2, and 2 times greater
than those achieved in humans with 100 mg of losartan in combination with 25 mg of hydrochlorothiazide.
Fetal toxicity in rats, as evidenced by a slight increase in supernumerary ribs, was observed when
females were treated prior to and throughout gestation with 10 mg/kg/day losartan in combination with
2.5 mg/kg/day hydrochlorothiazide. As also observed in studies with losartan alone, adverse fetal and
neonatal effects, including decreased body weight, renal toxicity, and mortality, occurred when pregnant
rats were treated during late gestation and/or lactation with 50 mg/kg/day losartan in combination with
12.5 mg/kg/day hydrochlorothiazide. Respective AUCs for losartan, its active metabolite and
hydrochlorothiazide at these dosages in rats were approximately 35, 10 and 10 times greater than those
achieved in humans with the administration of 100 mg of losartan in combination with 25 mg
hydrochlorothiazide. When hydrochlorothiazide was administered without losartan to pregnant mice and
rats during their respective periods of major organogenesis, at doses up to 3000 and 1000 mg/kg/day,
respectively, there was no evidence of harm to the fetus.
Thiazides cross the placental barrier and appear in cord blood. There is a risk of fetal or neonatal
jaundice, thrombocytopenia, and possibly other adverse reactions that have occurred in adults.
Nursing Mothers
It is not known whether losartan is excreted in human milk, but significant levels of losartan and its active
metabolite were shown to be present in rat milk. Thiazides appear in human milk. Because of the
potential for adverse effects on the nursing infant, a decision should be made whether to discontinue
nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric Use
Safety and effectiveness of HYZAAR in pediatric patients have not been established.
Neonates With A History Of In Utero Exposure To HYZAAR
If oliguria or hypotension occurs, direct attention
toward support of blood pressure and renal perfusion. Exchange transfusion or dialysis may be required
as means of reversing hypotension and/or substituting for disordered renal function.
Geriatric Use
In a controlled clinical study for the reduction in the combined risk of cardiovascular death, stroke and
myocardial infarction in hypertensive patients with left ventricular hypertrophy, 2857 patients (62%) were
65 years and over, while 808 patients (18%) were 75 years and over. In an effort to control blood
pressure in this study, patients were coadministered losartan and hydrochlorothiazide 74% of the total
time they were on study drug. No overall differences in effectiveness were observed between these
patients and younger patients. Adverse events were somewhat more frequent in the elderly compared to
non-elderly patients for both the losartan-hydrochlorothiazide and the control groups [see CLINICAL PHARMACOLOGY].
Race
In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, Black patients with
hypertension and left ventricular hypertrophy treated with atenolol had a lower risk of stroke, the primary
composite endpoint, as compared with Black patients treated with losartan (both cotreated with
hydrochlorothiazide in the majority of patients). In the subgroup of Black patients (n=533, 6% of the LIFE
study patients), there were 29 primary endpoints among 263 patients on atenolol (11%, 26 per 1000
patient-years) and 46 primary endpoints among 270 patients (17%, 42 per 1000 patient-years) on
losartan. This finding could not be explained on the basis of differences in the populations other than race
or on any imbalances between treatment groups. In addition, blood pressure reductions in both treatment
groups were consistent between Black and non-Black patients. Given the difficulty in interpreting subset
differences in large trials, it cannot be known whether the observed difference is the result of chance.
However, the LIFE study provides no evidence that the benefits of losartan on reducing the risk of
cardiovascular events in hypertensive patients with left ventricular hypertrophy apply to Black patients
[see CLINICAL PHARMACOLOGY].
Hepatic Impairment
Initiation of HYZAAR is not recommended for patients with hepatic impairment because the appropriate
starting dose of losartan, 25 mg, is not available.
Renal Impairment
Changes in renal function have been reported in susceptible individuals [see DOSAGE AND ADMINISTRATION , WARNINGS AND PRECAUTIONS , and CLINICAL PHARMACOLOGY]. Safety and effectiveness of
HYZAAR in patients with severe renal impairment (creatinine clearance <30 mL/min) have not been
established.