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| General
Information |
 Brand
Name: |
 ADALAT® XL® |
 Manufacturer: |
 Bayer |
 Scientific Name: |
 Nifedipine |
 Application: |
 Antianginal -
Antihypertensive |
| System Components and
Performance |
|
Adalat XL extended release tablets, while
similar in appearance to a conventional tablet, nonetheless consist
of a semipermeable membrane surrounding an osmotically active drug
core. The core itself is divided into 2 layers: an “active” layer
containing the drug, and a “push” layer containing pharmacologically
inert, but osmotically active components. As water from the
gastrointestinal tract enters the tablet, pressure increases in the
osmotic layer and
“pushes” against the
drug layer, forcing drug through the orifice in the active
layer.
Drug delivery is essentially constant as long as the
osmotic gradient remains constant, and then gradually falls to zero
as drug is exhausted from the tablet. Upon swallowing, the
biologically inert components of the tablet remain intact during
gastrointestinal transit and are eliminated in the feces as an
insoluble shell. |
| Pharmacology |
|
Nifedipine is a
calcium ion influx inhibitor (calcium channel blocker or calcium ion
antagonist).
The antianginal and
antihypertensive actions of nifedipine are believed to be related to
a specific cellular action of selectively inhibiting transmembrane
influx of calcium ions into cardiac muscle and vascular smooth
muscle. The contractile processes of these tissues are dependent
upon the movement of extracellular calcium into the cells through
specific ion channels. Nifedipine selectively inhibits the
transmembrane influx of calcium through the slow channel without
affecting, to any significant degree, the transmembrane influx of
sodium through the fast channel. This results in a reduction of free
calcium ions available within the muscle cells and an inhibition of
the contractile processes. Nifedipine does not alter total serum
calcium.
The specific mechanisms by which
nifedipine relieves angina and reduces blood pressure have not been
fully determined but are believed to be brought about largely by its
vasodilatory action.
Nifedipine dilates the main
coronary arteries and coronary arterioles both in normal and
ischemic regions resulting in an increase in blood flow and hence in
myocardial oxygen delivery.
Nifedipine by its vasodilatory
action on peripheral arterioles, reduces the total peripheral
vascular resistance. This reduces the workload of the heart and thus
reduces myocardial energy consumption and oxygen requirements which
probably accounts for the effectiveness of nifedipine in chronic
stable angina.
The mechanism by which nifedipine
reduces arterial blood pressure involves peripheral arterial
vasodilation and subsequent reduction in peripheral vascular
resistance. The increased peripheral vascular resistance that is an
underlying cause of hypertension results from an increase in active
tension in the vascular smooth muscle. Studies have demonstrated
that the increase in active tension reflects an increase in
cytosolic free calcium.
The negative inotropic effect of
nifedipine is usually not of major clinical significance because at
therapeutic doses, nifedipine's vasodilatory property evokes a
baroreceptor mediated reflex tachycardia which tends to
counterbalance this negative inotropic effect. Continued
administration of nifedipine to hypertensive patients has shown no
significant increase in heart rate.
Although nifedipine causes a
slight depression of sinoatrial node function and AV conduction in
isolated myocardial preparations, such effects have not been seen in
studies in intact animals or in man. In formal electrophysiologic
studies, predominantly in patients with normal conduction systems,
nifedipine has had no tendency to prolong AV conduction or sinus
node recovery time, or to slow sinus rate.
Pharmacokinetics: Nifedipine is
completely absorbed after oral administration. Plasma drug
concentrations rise at a gradual, controlled rate exhibiting
zero-order absorption kinetics after nifedipine administration and
reach a plateau at approximately 6 hours after the first dose. For
subsequent doses, relatively constant plasma concentrations at this
plateau are maintained with minimal fluctuations over the 24-hour
dosing interval. About a 4-fold higher fluctuation index (ratio of
peak to trough plasma concentration) was observed with the
conventional immediate release Adalat capsule at t.i.d. dosing than
with once daily Adalat XL tablets. At steady state the
bioavailability of the Adalat XL tablet is 86% relative to Adalat
capsules. Administration of the Adalat XL tablet in the presence of
food slightly alters the early rate of drug absorption, but does not
influence the extent of drug bioavailability. Markedly reduced
gastrointestinal retention time over prolonged periods (i.e., short
bowel syndrome), however, may influence the pharmacokinetic profile
of the drug which could potentially result in lower plasma
concentrations. Pharmacokinetics of Adalat XL tablets are linear
over the dose range of 30 to 180 mg in that plasma drug
concentrations are proportional to dose administered. There was no
evidence of dose dumping either in the presence or absence of food.
Nifedipine is extensively
metabolized to highly water-soluble, inactive metabolites accounting
for 60 to 80% of the dose excreted in the urine. The remainder is
excreted in the feces in metabolized form, most likely as a result
of biliary excretion. The main metabolite (95%) is the
hydroxycarbolic acid derivative, the remaining 5% is the
corresponding lactone. Only traces (less that 0.1% of the dose) of
unchanged nifedipine can be detected in the urine. Thus, the
pharmacokinetics of nifedipine are not significantly influenced by
the degree of renal impairment. Patients in hemodialysis or chronic
ambulatory peritoneal dialysis have not reported significantly
altered pharmacokinetics of nifedipine.
Since hepatic biotransformation
is the predominant route for the disposition of nifedipine, the
pharmacokinetics may be altered in patients with chronic liver
disease. Pharmacokinetic studies in patients with hepatic cirrhosis
showed a clinically significant prolongation of elimination
half-life and a decrease in total clearance of nifedipine. The
degree of serum protein binding of nifedipine is high (92 to 98%).
Protein binding may be greatly reduced in patients with renal or
hepatic impairment (see Precautions).
Nifedipine is metabolized by the
cytochrome P450 enzyme system, predominantly via CYP3A4, but also by
CYP1A2 and CYP2A6 isoenzymes.
Compounds found in grapefruit
juice inhibit the cytochrome P450 system, especially CYP3A4. In a
grapefruit juice-nifedipine interaction study in healthy male
volunteers pharmacokinetics of nifedipine showed significant
alteration. Following administration of a single dose of nifedipine
10 mg with 250 mL of grapefruit juice, the mean value of nifedipine
AUC increased by 34% and the tmax increased from 0.8 to 1.2 hours,
as compared to water (see Precautions, Interaction With Grapefruit
Juice). |
| Indications |
|
Chronic Stable Angina: In the
management of chronic stable angina (effort-associated angina)
without evidence of vasospasm in patients who
remain symptomatic despite adequate doses of beta-blockers and/or nitrates,
or who cannot tolerate these agents.
May
be used in combination with beta-blocking drugs in patients with
chronic stable angina. However, available information is not
sufficient to predict with confidence the effects of concurrent
treatment, especially in patients with compromised left ventricular
function or cardiac conduction abnormalities. When introducing such
concomitant therapy, care must be taken to monitor blood pressure
closely, since severe hypotension
can occur from the combined effects of the drugs (see
Warnings).
Hypertension: In the management
of mild to moderate essential hypertension. Should normally be used
in those patients in whom treatment with diuretics or beta-blockers
has been ineffective, or has been associated with unacceptable
adverse effects.
It can be tried as an initial
agent in those patients in whom the use of diuretics and/or
beta-blockers is contraindicated, or in patients with medical
conditions in which these drugs frequently cause serious adverse
effects.
Combination of Adalat XL with a
diuretic has been found compatible and has shown added
antihypertensive effect.
Safety of concurrent use of
Adalat XL with other antihypertensive agents has not been
established. |
| Contraindications |
|
Pregnancy and Lactation: Nifedipine is contraindicated in
pregnancy, during lactation, and in women of childbearing potential.
Fetal malformations and adverse effects on pregnancy have been
reported in animals.
An increase in the number of fetal mortalities and resorptions
occurred after the administration of 30 and 100 mg/kg of nifedipine
to pregnant mice, rats and rabbits. Fetal malformations occurred
after the administration of 30 and 100 mg/kg nifedipine to pregnant
mice and 100 mg/kg to pregnant rats.
In patients with hypersensitivity to nifedipine.
In patients with severe hypotension. |
| Warnings |
|
Excessive Hypotension in Patients with Angina:
Since nifedipine lowers peripheral vascular resistance and blood
pressure, it should be used cautiously in patients with angina who
are prone to develop hypotension and those with a history of
cerebrovascular insufficiency. Occasional patients have had
excessive and poorly tolerated hypotension. Syncope has been
reported (see Adverse Effects). These responses have usually
occurred during initial titration or at the time of subsequent
upward dosage adjustment, and may be more likely in patients on
concomitant beta-blockers. If excessive hypotension occurs, dosage
should be lowered or the drug should be discontinued (see
Contraindications).
Severe hypotension and/or
increased fluid volume requirements have been reported in patients
receiving nifedipine, with a beta-blocker, who underwent coronary
artery bypass surgery using high dose fentanyl anesthesia. The
interaction with high dose fentanyl appears to be due to the
combination of nifedipine and a beta-blocker, but the possibility
that it may occur with nifedipine alone, with low doses of fentanyl
in other surgical procedures, or with other narcotic analgesics
cannot be ruled out. In nifedipine-treated patients where surgery
using high dose fentanyl anesthesia is contemplated, the physician
should be aware of these potential problems and if the patient's
condition permits, sufficient time (at least 36 hours), should be
allowed for nifedipine to be washed out of the body prior to
surgery.
The following information should
be taken into account in those patients who are being treated for
hypertension as well as angina.
Increased Angina and/or
Myocardial Infarction: Rarely, patients, particularly those who have
severe obstructive coronary artery disease have developed
well-documented increased frequency, duration and/or severity of
angina or acute myocardial infarction on starting nifedipine or at
the time of dosage increase. The mechanism of the response is not
established.
Since there has not been a study
of Adalat XL in acute myocardial infarction reported, similar
effects of Adalat XL to that of immediate-release nifedipine cannot
be excluded. Immediate-release nifedipine is contraindicated in
acute myocardial infarction.
Beta-blocker Withdrawal: Patients
with angina recently withdrawn from beta-blockers may develop a
withdrawal syndrome with increased angina, probably related to
increased sensitivity to catecholamines. Initiation of treatment
with nifedipine will not prevent this occurrence and might be
expected to exacerbate it by provoking reflex catecholamine release.
There have been occasional reports of increased angina in a setting
of beta-blocker withdrawal and initiation of nifedipine. It is
important to taper beta-blockers if possible, rather than stopping
them abruptly before beginning nifedipine.
Patients with Heart Failure:
There have been isolated reports of severe hypotension and lowering
of cardiac output following administration of nifedipine to patients
with severe heart failure. Thus, nifedipine should be used
cautiously in patients with severe heart failure. Rarely, patients
usually receiving a beta-blocker, have developed heart failure after
beginning nifedipine therapy.
In patients with severe aortic
stenosis, nifedipine will not produce its usual afterload reducing
effects and there is a possibility that an unopposed negative
inotropic action of the drug may produce heart failure if the
end-diastolic pressure is raised. Caution should therefore be
exercised when using nifedipine in patients with these conditions.
Patients with Pre-existing
Gastrointestinal Narrowing: Since the Adalat XL delivery system
contains a nondeformable material, caution should be used when
administering it in patients with pre-existing severe
gastrointestinal narrowing (pathologic or iatrogenic). There have
been rare reports of obstructive symptoms in patients with known
strictures in association with the ingestion of Adalat XL tablets. |
| Precautions |
|
Hypotension/Heart Rate: Because nifedipine is
an arterial and arteriolar vasodilator, hypotension and a
compensatory increase in heart rate may occur. Thus, blood pressure
and heart rate should be monitored carefully during nifedipine therapy. Close monitoring is
especially recommended for patients who are prone to develop hypotension,
those with a history of cerebrovascular insufficiency, and those who are
taking medications that are known to lower blood pressure (see
Warnings).
Peripheral Edema: Mild to
moderate peripheral edema, typically associated with arterial
vasodilation and not due to left ventricular dysfunction, has been
reported to occur in patients treated with nifedipine (see Adverse
Effects). This edema occurs primarily in the lower extremities and
may respond to diuretic therapy. With patients whose angina or
hypertension is complicated by congestive heart failure, care should
be taken to differentiate this peripheral edema from the effects of
increasing left ventricular dysfunction.
Geriatrics: Nifedipine should be
administered cautiously to elderly patients, especially to those
with a history of hypotension or cerebral vascular insufficiency.
Diabetic Patients: The use of
nifedipine in diabetic patients may require adjustment for their
control.
Patients With Impaired Liver
Function: Nifedipine should be used with caution in patients with
impaired liver function (see Pharmacology). A dose reduction,
particularly in severe cases, may be required. Close monitoring of
response and metabolic effect should apply.
Interaction With Grapefruit
Juice: Published data indicate that through inhibition of cytochrome
P450, flavonoids present in the grapefruit juice can increase plasma
levels and augment pharmacodynamic effects of some dihydropyridine
calcium channel blockers, including nifedipine (see Pharmacology).
Therefore, the administration of nifedipine with grapefruit juice
should be avoided.
Drug Interactions : As
with all drugs, care should be exercised when treating patients with
multiple medications. Dihydrophyridine calcium channel blockers
undergo biotransformation by the cytochrome P450 system, mainly via
the CYP3A4 isoenzyme. Coadministration of nifedipine with other
drugs which follow the same route of biotransformation may result in
alter bioavailability. Dosages of similarly metabolized drugs,
particularly those of low therapeutic ratio, and especially in
patients with renal and/or hepatic impairment, may require
adjustment when starting or stopping concomitantly administered
nifedipine to maintain optimum therapeutic blood levels.
Drugs known to be inhibitors of
the cytochrome P450 system include: azole antifungals, cimetidine,
cyclosporine, erythromycin, quinidine, terfenadine and warfarin.
Drugs known to be inducers of the
cytochrome P450 system include: phenobarbital, phenytoin and
rifampin.
Drugs known to be biotransformed
via cytochrome P450 include: benzodiazepines, flecainide,
theophylline, imipramine and propafenone.
Beta Adrenergic Blocking Agents:
Concomitant administration of nifedipine and beta-blocking agents is
usually well tolerated but there have been occasional literature
reports suggesting that the combination may increase the likelihood
of congestive heart failure, severe hypotension, or exacerbation of
angina. Therefore, caution and careful monitoring of patients on
concomitant therapy is recommended (see Indications and Warnings).
Long-acting Nitrates: Nifedipine
may be safely coadministered with nitrates, but there have been no
controlled studies to evaluate the antianginal effectiveness of this
combination.
Digoxin: Administration of
nifedipine with digoxin may lead to reduced digoxin clearance, and
therefore, an increase in the plasma digoxin level. It is
recommended that digoxin levels be monitored when initiating,
adjusting and discontinuing nifedipine to avoid possible “under-” or
“over-” dosing with digitalis.
Coumarin Anticoagulants: There
have been rare reports of increased prothrombin time in patients
taking coumarin anticoagulants to whom nifedipine was administered.
However, the relationship to nifedipine therapy is uncertain.
Quinidine: The addition of
nifedipine to a stable quinidine regimen may reduce the quinidine by
50%, an enhanced response to nifedipine may also occur. The addition
of quinidine to a stable nifedipine regimen may result in elevated
nifedipine concentrations and a reduced response to quinidine. Some
patients have experienced elevated quinidine levels when nifedipine
was discontinued. Therefore, patients receiving concomitant therapy
of nifedipine and quinidine, or those who had their nifedipine
discontinued while still receiving quinidine, should be closely
monitored, including determination of plasma levels of quinidine.
Consideration should be given to dosage adjustment.
Cimetidine and Ranitidine:
Pharmacokinetic studies have shown that concurrent administration of
cimetidine or ranitidine with nifedipine results in significant
increases in nifedipine plasma levels (ca. 80% with cimetidine, and
70% with ranitidine). Patients receiving either of these drugs
concomitantly with nifedipine should be monitored carefully for the
possible exacerbation of effects of nifedipine, such as hypotension.
Adjustment of nifedipine dosage may be necessary.
Information for Patients: Adalat
XL tablets must be swallowed whole. Patients should be advised to
not chew, divide or crush the tablet as this can result in a massive
immediate release of the drug. In Adalat XL, the medication is
packed within a nonabsorbable shell that has been specially designed
to slowly release the drug so the body can absorb it. When this is
completed, the empty tablet is eliminated in the stool. |
| Adverse
Effects |
|
Angina: In 257 chronic stable angina patients treated in
controlled and long-term open studies, adverse effects were reported in 30%
of patients and required discontinuation of therapy in 8.5% of
patients.
The most common adverse effects
were: edema (10.1%), headache (3.1%) and angina pectoris (3.1%).
The following adverse effects
were also reported. Incidences greater than 1% are given in
parenthesis: Cardiovascular: palpitation (2.3%), tachycardia,
myocardial infarction, ventricular arrhythmia, extrasystoles,
dyspnea, chest pain.
In patients with angina, rarely,
and possibly due to tachycardia, nifedipine has been reported to
have precipitated an angina pectoris attack. In addition, more
serious events were occasionally observed, not readily
distinguishable from the natural history of the disease in these
patients. It remains possible, however, that some or many of these
events were drug related. These events include myocardial
infarction, congestive heart failure or pulmonary edema, and
ventricular arrhythmias or conduction disturbances.
CNS: dizziness (2.3%),
hypoesthesia (1.2%), confusion, insomnia, somnolence, nervousness,
asthenia, hyperkinesia.
Gastrointestinal: constipation
(1.9%), dyspepsia (1.2%), abdominal pain (1.2%), diarrhea, nausea,
melena.
Genitourinary: impotence,
hematuria, polyuria, dysuria.
Musculoskeletal: leg cramps,
paresthesia, myalgia, arthralgia.
Dermatologic: rash, pruritus.
Other: fatigue (1.2%), pain,
periorbital edema.
Hypertension: In 661 hypertensive
patients treated in controlled trials with nifedipine, adverse
effects were reported in 54% of patients and required
discontinuation of therapy in 11.9% of patients. The majority of
adverse effects reported occurred within the first 3 months of
therapy.
The most common adverse effects
reported were edema, which was dose related and ranged in frequency
from approximately 10 to 30% in the 30 to 120 mg dose range,
headache (16.6%), fatigue (6.2%), dizziness (4.4%), constipation
(3.5%) and nausea (3.5%).
The following adverse effects
were also reported. Incidences greater than 1% are given in
parenthesis: Cardiovascular: flushing (2.4%), palpitation (2.3%),
tachycardia (1.2%), chest pain (1.1%), ventricular arrhythmia,
hypotension, syncope.
CNS: insomnia (1.8%), nervousness
(1.8%), somnolence (1.5%), depression, tremor, decreased libido,
migraine, vertigo, amnesia, anxiety, impaired concentration,
twitching, ataxia, hypertonia, paresthesia, hypoesthesia.
Gastrointestinal: dyspepsia
(1.5%), flatulence (1.5%), abdominal pain (1.4%), dry mouth (1.1%),
diarrhea, vomiting, thirst, melena, eructation, weight increase.
Genitourinary: impotence
(1.5%), polyuria (1.5%), dysuria, nocturia, oliguria, urinary
incontinence, urinary frequency, menstrual disorder.
Musculoskeletal: arthralgia, back
pain, myalgia.
Special Senses: abnormal vision,
abnormal lacrimation, taste disturbance, conjunctivitis, tinnitus.
Dermatologic: rash (2.3%),
pruritus (1.1%), erythematous rash, alopecia.
Respiratory: dyspnea (1.7%),
bronchospasm, pharyngitis, upper respiratory tract infection,
epistaxis.
Other: leg cramps (2.7%), pain
(2.7%), asthenia (2.0%), face edema, gout, allergy, fever, breast
pain.
An open, nonrandomized
postmarketing surveillance study (EXACT), involving 1 700 mild to
moderate hypertensive patients, was conducted in the offices of
general practitioners across Canada. Patients were enrolled in the
study if they had been previously treated with either single or dual
antihypertensive therapy and the physician considered Adalat XL an
appropriate monotherapy. Patients were to be started on Adalat XL 30
mg. If after 3 or 6 weeks of therapy with Adalat XL 30 mg, blood
pressure was uncontrolled (i.e., sitting diastolic blood pressure
was >95 mm Hg), then the patient was given 60 mg Adalat XL at the
physician's discretion. Twelve patients were started immediately on
Adalat XL 60 mg. Patients were followed for 20 weeks. Adverse events
were reported in 605/1 700 patients (35.6%). These adverse events
were typical of those seen with the dihydropyridine class of calcium
channel blockers (edema, headache, dizziness) and are related to the
vasodilatory properties of this class of compounds.
The following adverse events have
been reported with nifedipine rarely.
Rare instances of allergic
hepatitis, cholestasis with, or without jaundice have been reported
in patients treated with nifedipine.
Gingival hyperplasia similar to
that caused by phenytoin has been reported in patients treated with
nifedipine. The lesions usually regressed on discontinuation of the
drug. However on occasion, gingivectomy was necessary.
Gynecomastia has been observed
rarely in older men on long-term therapy, but has so far always
regressed completely on discontinuation of the drug.
Isolated cases of angioedema have
been reported. Angioedema may be accompanied by breathing
difficulty. Anaphylaxis has been reported rarely.
In postmarketing experience,
there have been rare reports of exfoliative dermatitis and
Stevens-Johnson syndrome. Gastrointestinal irritation and
gastrointestinal bleeding were also reported; however, the causal
relationship is uncertain.
Laboratory Tests: Rare, usually
transient, but occasionally significant elevations of enzymes such
as CPK, AST and ALT have been noted. The relationship to drug
therapy is uncertain in most cases, but probable in some. These
laboratory abnormalities have rarely been associated with clinical
symptoms, however, cholestasis with or without jaundice has been
reported.
An increase (5.4%) in mean
alkaline phosphatase was noted in patients treated with nifedipine.
This was an isolated finding not associated with clinical symptoms
and rarely resulted in values which exceeded the upper limit of the
normal range.
Serum potassium was unchanged in
patients receiving nifedipine in the absence of concomitant diuretic
therapy, and slightly decreased in patients receiving concomitant
diuretics.
Nifedipine decreases platelet
aggregation in vitro. Limited clinical studies have demonstrated a
moderate but statistically significant decrease in platelet
aggregation and increase in bleeding time in some nifedipine treated
patients. This is thought to be a function of inhibition of calcium
transport across the platelet membrane. No clinical significance for
these findings has been demonstrated.
Positive direct Coombs' tests,
with or without associated hemolytic anemia, have been reported but
a causal relationship between nifedipine administration and
positivity of this laboratory test, including hemolysis, could not
be determined.
Rare reversible elevations in BUN
and serum creatinine have been reported in patients with
pre-existing chronic renal insufficiency. The relationship to
therapy with nifedipine is uncertain in most cases, but probable in
some. |
| Overdose
|
|
Symptoms: There are several
well documented cases of nifedipine overdosage. The following
symptoms are observed in cases of severe nifedipine intoxication:
disturbance of consciousness to the point of coma, a drop in blood
pressure, tachycardia/bradycardia, hyperglycemia, metabolic acidosis, hypoxia, cardiogenic shock with pulmonary
edema.
Treatment: As
far as treatment is concerned, elimination of the active substance
and the restoration of stable cardiovascular conditions have
priority. After oral ingestion, thorough gastric lavage is
indicated, if necessary in combination with irrigation of the small
intestine. Particularly in cases of intoxication with slow-release
products like Adalat XL, elimination must be as complete as possible
including the small intestine to prevent the otherwise inevitable
subsequent absorption of the active substance. Hemodialysis serves
no purpose, as nifedipine is not dialyzable, but plasmapheresis is
advisable (high plasma protein binding, relatively low volume of
distribution).
Clinically significant
hypotension calls for active cardiovascular support including
monitoring of cardiac and respiratory function including elevation
of extremities and attention to circulating fluid volume and urine
output.
Hypotension as a result of
arterial vasodilation can also be treated with calcium (10 mL of 10%
calcium gluconate solution administered slowly via i.v. route and
repeated if necessary). As a result, the serum calcium can reach the
upper normal range to slightly elevated levels. If an insufficient
increase in blood pressure is achieved with calcium,
vasoconstricting sympathomimetics such as dopamine or norepinephrine
are additionally administered as a last resort only in patients
without cardiac arrhythmia or ischemic heart disease and when other
safer measures have failed. The dosage of these drugs is determined
solely by the effect obtained. Additional liquid or volume must be
administered with caution because of the danger of overloading the
heart.
Bradycardia and/or
bradyarrhythmias have been observed in some cases of nifedipine
overdosage. Appropriate clinical measures, according to the nature
and severity of the symptoms, should be applied. |
| Dosage
|
|
Dosage should be individualized depending on patient tolerance and
response.
Adalat XL tablets must be
swallowed whole and should not be bitten or divided.
In general, titration steps
should proceed over a 7 to 14 day period so that the physician can
assess the response to each dose level before proceeding to higher
doses. Since steady-state plasma levels are achieved on the second
day of dosing, if symptoms so warrant, titration may proceed more
rapidly provided that the patient is closely monitored. v
Angina: Therapy should normally
be initiated with 30 mg once daily. Experience with doses greater
than 90 mg daily in patients with angina is limited; therefore,
doses greater than 90 mg daily are not recommended.
Angina patients controlled on
Adalat capsules alone or in combination with beta-blockers may be
safely switched to Adalat XL tablets at the nearest equivalent daily
dose. Subsequent titration to higher or lower doses may be necessary
and should be initiated as clinically warranted.
Hypertension: Therapy should
normally be initiated with 30 mg once daily. Some patients, such as
the elderly, may benefit from initiation of therapy at 20 mg once
daily. The usual maintenance dose is 30 to 60 mg once daily. Doses
greater than 90 mg are not recommended.
Patients switched from Adalat PA
10 or 20 to Adalat XL therapy should receive an initial dosage of
Adalat XL no higher than 30 mg once daily, based on previously
prescribed dosing regimen. If clinically warranted, the dosage of
Adalat XL should be increased to 60 mg once daily. Blood pressure
and patient symptoms should be monitored closely following the
switch from Adalat PA to Adalat XL.
No “rebound effect” has been
observed upon discontinuation of Adalat XL. However, if
discontinuation of nifedipine is necessary, sound clinical practice
suggests that the dosage should be decreased gradually under close
physician supervision. |
| Supplied |
|
20 mg: Each dusty rose,
extended-release tablet, imprinted with “ADALAT 20” on one side,
contains: nifedipine 20 mg. Nonmedicinal ingredients: cellulose acetate, hydroxypropylcellulose, hydroxypropyl
methylcellulose, magnesium stearate, Opadry OY-S-24914, polyethylene glycol, polyethylene oxide, red ferric
oxide, sodium chloride and titanium dioxide. Bottles of 100 and
500.
30 mg: Each
dusty rose, extended-release tablet, imprinted with “ADALAT 30” on
one side, contains: nifedipine 30 mg. Nonmedicinal ingredients:
cellulose acetate, hydroxypropylcellulose, hydroxypropyl
methylcellulose, magnesium stearate, pharmaceutical shellac,
polyethylene glycol, polyethylene oxide, red ferric oxide, sodium
chloride, synthetic black iron oxide and titanium dioxide.
Lactose-free. Bottles of 100 and 500.
60 mg: Each
dusty rose, extended-release tablet, imprinted with “ADALAT 60” on
one side, contains: nifedipine 60 mg. Nonmedicinal ingredients:
cellulose acetate, hydroxypropylcellulose, hydroxypropyl
methylcellulose, magnesium stearate, pharmaceutical shellac,
polyethylene glycol, polyethylene oxide, red ferric oxide, sodium
chloride, synthetic black iron oxide and titanium dioxide.
Lactose-free. Bottles of 100.
Store between 15 and 30°C.
Protect from light, humidity and moisture.
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