A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Nalfon Side Effects, and Drug Interactions - Fenoprofen
Nalfon Side Effects, and Drug Interactions - Fenoprofen
SIDE EFFECTS
During clinical studies for rheumatoid arthritis, osteoarthritis, or mild to
moderate pain and studies of pharmacokinetics, complaints were compiled from
a checklist of potential adverse reactions, and the following data emerged.
These encompass observations in 6,786 patients, including 188 observed for at
least 52 weeks. For comparison, data are also presented from complaints received
from the 266 patients who received placebo in these same trials. During short-term
studies for analgesia, the incidence of adverse reactions was markedly lower
than that seen in longer-term studies.
INCIDENCE GREATER THAN 1%
Probable Causal Relationship
Digestive System During clinical trials with Nalfon, the most
common adverse reactions were gastrointestinal in nature and occurred in 20.8%
of patients receiving Nalfon as compared to 16.9% of patients receiving placebo.
In descending order of frequency, these reactions included dyspepsia (10.3%,
Nalfon, vs 2.3%, placebo), nausea (7.7% vs 7.1%), constipation (7% vs 1.5%),
vomiting (2.6% vs 1.9%), abdominal pain (2% vs 1.1%), and diarrhea (1.8% vs
4.1%).
The drug was discontinued because of adverse gastrointestinal reactions in
less than 2% of patients during premarketing studies.
Nervous System The most frequent adverse neurologic reactions
were headache (8.7% treated vs 7.5% placebo) and somnolence (8.5% vs 6.4%).
Dizziness (6.5% vs 5.6%), tremor (2.2% vs 0.4%), and confusion (1.4% vs none)
were noted less frequently.
Nalfon was discontinued in less than 0.5% of patients because of these side
effects during premarketing studies.
Skin and Appendages Increased sweating (4.6% vs 0.4%), pruritus
(4.2% vs 0.8%), and rash (3.7% vs 0.4%) were reported.
Nalfon was discontinued in about 1% of patients because of an adverse effect
related to the skin during premarketing studies.
Special Senses Tinnitus (4.5% vs 0.4%), blurred vision (2.2%
vs none), and decreased hearing (1.6% vs none) were reported.
Nalfon was discontinued in less than 0.5% of patients because of adverse effects
related to the special senses during premarketing studies.
Cardiovascular Palpitations (2.5% vs 0.4%).
Nalfon was discontinued in about 0.5% of patients because of adverse cardiovascular
reactions during premarketing studies.
Miscellaneous Nervousness (5.7% vs 1.5%), asthenia (5.4% vs
0.4%), peripheral edema (5.0% vs 0.4%), dyspnea (2.8% vs none), fatigue (1.7%
vs 1.5%), upper respiratory infection (1.5% vs 5.6%), and nasopharyngitis (1.2%
vs none).
INCIDENCE LESS THAN 1%
Probable Causal Relationship
The following adverse reactions, occurring in less than 1% of patients, were
reported in controlled clinical trials and voluntary reports made since Nalfon
was initially marketed. The probability of a causal relationship exists between
Nalfon and these adverse reactions:
Digestive System Gastritis, peptic ulcer with/without perforation,
gastrointestinal hemorrhage, anorexia, flatulence, dry mouth, and blood in the
stool. Increases in alkaline phosphatase, LDH, and SGOT, jaundice, and cholestatic
hepatitis were observed ( see Precautions).
Genitourinary Tract Renal failure, dysuria, cystitis, hematuria,
oliguria, azotemia, anuria, interstitial nephritis, nephrosis, and papillary
necrosis ( see WARNINGS).
Hypersensitivity Angioedema (angioneurotic edema).
Hematologic Purpura, bruising, hemorrhage, thrombocytopenia,
hemolytic anemia, aplastic anemia, agranulocytosis, and pancytopenia.
Miscellaneous Anaphylaxis, urticaria, malaise, insomnia, and
tachycardia.
INCIDENCE LESS THAN 1%
Causal Relationship Unknown
Other reactions reported either in clinical trials or spontaneously, occurred
in circumstances in which a causal relationship could not be established. However,
with these rarely reported reactions, the possibility of such a relationship
cannot be excluded. Therefore, these observations are listed to alert the physician.
Skin and Appendages Exfoliative dermatitis, toxic epidermal
necrolysis, Stevens-Johnson syndrome, and alopecia.
Digestive System Aphthous ulcerations of the buccal mucosa,
metallic taste, and pancreatitis.
Cardiovascular Atrial fibrillation, pulmonary edema, electrocardiographic
changes, and supraventricular tachycardia.
Nervous System Depression, disorientation, seizures, and trigeminal
neuralgia.
Special Senses Burning tongue, diplopia, and optic neuritis.
Miscellaneous Personality change, lymphadenopathy, mastodynia,
and fever.
DRUG INTERACTIONS
The coadministration of aspirin decreases the biologic half-life of fenoprofen because of an increase in metabolic clearance
that results in a greater amount of hydroxylated fenoprofen in the urine. Although
the mechanism of interaction between fenoprofen and aspirin is not totally known,
enzyme induction and displacement of fenoprofen from plasma albumin binding
sites are possibilities. Because Nalfon has not been shown to produce any additional
effect beyond that obtained with aspirin alone and because aspirin increases
the rate of excretion of Nalfon, the concomitant use of Nalfon and salicylates
is not recommended.
Chronic administration of phenobarbital, a known enzyme inducer, may be associated
with a decrease in the plasma half-life of fenoprofen. When phenobarbital is
added to or withdrawn from treatment, dosage adjustment of Nalfon may be required.
In vitro studies have shown that fenoprofen, because of its affinity for albumin,
may displace from their binding sites other drugs that are also albumin bound,
and this may lead to drug interaction. Theoretically, fenoprofen could likewise
be displaced. Patients receiving hydantoins, sulfonamides, or sulfonylureas
should be observed for increased activity of these drugs and, therefore, signs
of toxicity from these drugs. In patients receiving coumarin-type anticoagulants,
the addition of Nalfon to therapy could prolong the prothrombin time. Patients
receiving both drugs should be under careful observation. Patients treated with
Nalfon may be resistant to the effects of loop diuretics.
In patients receiving Nalfon and a steroid concomitantly, any reduction in
steroid dosage should be gradual in order to avoid the possible complications
of sudden steroid withdrawal.
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