Anaphylactoid and Possibly Related Reactions
Presumably because angiotensin-converting enzyme inhibitors affect the metabolism of eicosanoids and polypeptides, including endogenous bradykinin, patients receiving ACE inhibitors (including CAPOTEN) may be subject to a variety of adverse reactions, some of them serious.
Head and Neck Angioedema: Angioedema involving the extremities, face,
lips, mucous membranes, tongue, glottis or larynx has been seen in patients
treated with ACE inhibitors, including captopril. If angioedema involves the
tongue, glottis or larynx, airway obstruction may occur and be fatal. Emergency
therapy, including but not necessarily limited to, subcutaneous administration
of a 1:1000 solution of epinephrine should be promptly instituted.
Swelling confined to the face, mucous membranes of the mouth, lips and extremities
has usually resolved with discontinuation of captopril; some cases required
medical therapy. (See PRECAUTIONS: Information for
Patients and ADVERSE REACTIONS.)
Intestinal Angioedema: Intestinal angioedema has been reported in patients
treated with ACE inhibitors. These patients presented with abdominal pain (with
or without nausea or vomiting); in some cases there was no prior history of
facial angioedema and C-1 esterase levels were normal. The angioedema was diagnosed
by procedures including abdominal CT scan or ultrasound, or at surgery, and
symptoms resolved after stopping the ACE inhibitor. Intestinal angioedema should
be included in the differential diagnosis of patients on ACE inhibitors presenting
with abdominal pain.
Anaphylactoid reactions during desensitization: Two patients undergoing
desensitizing treatment with hymenoptera venom while receiving ACE inhibitors
sustained life-threatening anaphylactoid reactions. In the same patients, these
reactions were avoided when ACE inhibitors were temporarily withheld, but they
reappeared upon inadvertent rechallenge.
Anaphylactoid reactions during membrane exposure: Anaphylactoid reactions
have been reported in patients dialyzed with high-flux membranes and treated
concomitantly with an ACE inhibitor. Anaphylactoid reactions have also been
reported in patients undergoing low-density lipoprotein apheresis with dextran
sulfate absorption.
Neutropenia/Agranulocytosis
Neutropenia ( < 1000/mm3) with myeloid hypoplasia has resulted
from use of captopril. About half of the neutropenic patients developed systemic
or oral cavity infections or other features of the syndrome of agranulocytosis.
The risk of neutropenia is dependent on the clinical status of the patient:
In clinical trials in patients with hypertension who have normal renal function
(serum creatinine less than 1.6 mg/dL and no collagen vascular disease), neutropenia
has been seen in one patient out of over 8,600 exposed.
In patients with some degree of renal failure (serum creatinine at least 1.6 mg/dL) but no collagen vascular disease, the risk of neutropenia in clinical trials was about 1 per 500, a frequency over 15 times that for uncomplicated hypertension. Daily doses of captopril were relatively high in these patients, particularly in view of their diminished renal function. In foreign marketing experience in patients with renal failure, use of allopurinol concomitantly with captopril has been associated with neutropenia but this association has not appeared in U.S. reports.
In patients with collagen vascular diseases (e.g., systemic lupus erythematosus,
scleroderma) and impaired renal function, neutropenia occurred in 3.7 percent
of patients in clinical trials.
While none of the over 750 patients in formal clinical trials of heart failure developed neutropenia, it has occurred during the subsequent clinical experience. About half of the reported cases had serum creatinine ≥ 1.6 mg/dL and more than 75 percent were in patients also receiving procainamide. In heart failure, it appears that the same risk factors for neutropenia are present.
The neutropenia has usually been detected within three months after captopril was started. Bone marrow examinations in patients with neutropenia consistently showed myeloid hypoplasia, frequently accompanied by erythroid hypoplasia and decreased numbers of megakaryocytes (e.g., hypoplastic bone marrow and pancytopenia); anemia and thrombocytopenia were sometimes seen.
In general, neutrophils returned to normal in about two weeks after captopril was discontinued, and serious infections were limited to clinically complex patients. About 13 percent of the cases of neutropenia have ended fatally, but almost all fatalities were in patients with serious illness, having collagen vascular disease, renal failure, heart failure or immunosuppressant therapy, or a combination of these complicating factors.
Evaluation of the hypertensive or heart failure patient should always include
assessment of renal function.
If captopril is used in patients with impaired renal function, white blood
cell and differential counts should be evaluated prior to starting treatment
and at approximately two-week intervals for about three months, then periodically.
In patients with collagen vascular disease or who are exposed to other drugs
known to affect the white cells or immune response, particularly when there
is impaired renal function, captopril should be used only after an assessment
of benefit and risk, and then with caution.
All patients treated with captopril should be told to report any signs of infection (e.g., sore throat, fever). If infection is suspected, white cell counts should be performed without delay.
Since discontinuation of captopril and other drugs has generally led to prompt
return of the white count to normal, upon confirmation of neutropenia (neutrophil
count < 1000/mm3) the physician should withdraw captopril and closely
follow the patient's course.
Proteinuria
Total urinary proteins greater than 1 g per day were seen in about 0.7 percent of patients receiving captopril. About 90 percent of affected patients had evidence of prior renal disease or received relatively high doses of captopril (in excess of 150 mg/day), or both. The nephrotic syndrome occurred in about one-fifth of proteinuric patients. In most cases, proteinuria subsided or cleared within six months whether or not captopril was continued. Parameters of renal function, such as BUN and creatinine, were seldom altered in the patients with proteinuria.
Hypotension
Excessive hypotension was rarely seen in hypertensive patients but is a possible
consequence of captopril use in salt/volume depleted persons (such as those
treated vigorously with diuretics), patients with heart failure or those patients
undergoing renal dialysis. (See PRECAUTIONS: DRUG
INTERACTIONS.)
In heart failure, where the blood pressure was either normal or low, transient
decreases in mean blood pressure greater than 20 percent were recorded in about
half of the patients. This transient hypotension is more likely to occur after
any of the first several doses and is usually well tolerated, producing either
no symptoms or brief mild lightheadedness, although in rare instances it has
been associated with arrhythmia or conduction defects. Hypotension was the reason
for discontinuation of drug in 3.6 percent of patients with heart failure.
BECAUSE OF THE POTENTIAL FALL IN BLOOD PRESSURE IN THESE PATIENTS, THERAPY
SHOULD BE STARTED UNDER VERY CLOSE MEDICAL SUPERVISION. A starting dose
of 6.25 or 12.5 mg t.i.d. may minimize the hypotensive effect. Patients should
be followed closely for the first two weeks of treatment and whenever the dose
of captopril and/or diuretic is increased. In patients with heart failure, reducing
the dose of diuretic, if feasible, may minimize the fall in blood pressure.
Hypotension is not per se a reason to discontinue captopril. Some decrease of systemic blood pressure is a common and desirable observation upon initiation of CAPOTEN(captopril tablets, USP) treatment in heart failure. The magnitude of the decrease is greatest early in the course of treatment; this effect stabilizes within a week or two, and generally returns to pretreatment levels, without a decrease in therapeutic efficacy, within two months.
Fetal/Neonatal Morbidity and Mortality
ACE inhibitors can cause fetal and neonatal morbidity and death when administered to pregnant women. Several dozen cases have been reported in the world literature. When pregnancy is detected, ACE inhibitors should be discontinued as soon as possible.
The use of ACE inhibitors during the second and third trimesters of pregnancy has been associated with fetal and neonatal injury, including hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure, and death. Oligohydramnios has also been reported, presumably resulting from decreased fetal renal function; oligohydramnios in this setting has been associated with fetal limb contractures, craniofacial deformation, and hypoplastic lung development. Prematurity, intrauterine growth retardation, and patent ductus arteriosus have also been reported, although it is not clear whether these occurrences were due to the ACE-inhibitor exposure.
These adverse effects do not appear to have resulted from intrauterine ACE-inhibitor exposure that has been limited to the first trimester. Mothers whose embryos and fetuses are exposed to ACE inhibitors only during the first trimester should be so informed. Nonetheless, when patients become pregnant, physicians should make every effort to discontinue the use of captopril as soon as possible.
Rarely (probably less often than once in every thousand pregnancies), no alternative
to ACE inhibitors will be found. In these rare cases, the mothers should be
apprised of the potential hazards to their fetuses, and serial ultrasound examinations
should be performed to assess the intraamniotic environment.
If oligohydramnios is observed, captopril should be discontinued unless it
is considered life-saving for the mother. Contraction stress testing (CST),
a non-stress test (NST), or biophysical profiling (BPP) may be appropriate,
depending upon the week of pregnancy. Patients and physicians should be aware,
however, that oligohydramnios may not appear until after the fetus has sustained
irreversible injury.
Infants with histories of in utero exposure to ACE inhibitors should
be closely observed for hypotension, oliguria, and hyperkalemia. If oliguriaoccurs,
attention should be directed toward support of blood pressure and renal perfusion.
Exchange transfusion or dialysis may be required as a means of reversing hypotension
and/or substituting for disordered renal function. While captopril may be removed
from the adult circulation by hemodialysis, there is inadequate data concerning
the effectiveness of hemodialysis for removing it from the circulation of neonates
or children. Peritoneal dialysis is not effective for removingcaptopril; there
is no information concerning exchange transfusion for removing captopril from
the general circulation.
When captopril was given to rabbits at doses about 0.8 to 70 times (on a mg/kg basis) the maximum recommended human dose, low incidences of craniofacial malformations were seen. No teratogenic effects of captopril were seen in studies of pregnant rats and hamsters. On a mg/kg basis, the doses used were up to 150 times (in hamsters) and 625 times (in rats) the maximum recommended human dose.
Hepatic Failure
Rarely, ACE inhibitors have been associated with a syndrome that starts with cholestatic jaundice and progresses to fulminant hepatic necrosis and (sometimes) death. The mechanism of this syndrome is not understood. Patients receiving ACE inhibitors who develop jaundice or marked elevations of hepatic enzymes should discontinue the ACE inhibitor and receive appropriate medical follow-up.