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
Trimpex Side Effects, and Drug Interactions - Trimethoprim
Trimpex Side Effects, and Drug Interactions - Trimethoprim
SIDE EFFECTS
The adverse effects encountered most often with trimethoprim
were rash and pruritus. Other adverse effects reported involved
the gastrointestinal and hematopoietic
systems.
Dermatologic Reactions: Rash, pruritus
and exfoliative dermatitis. At the recommended dosage
regimens of 100 mg bid or
200 mg qd, each for 10 days,
the incidence of rash
is 2.9% to 6.7%. In clinical
studies which employed high doses of trimethoprim, an elevated incidence
of rash was noted. These
rashes were maculopapular,
morbilliform, pruritic and generally mild to moderate, appearing
7 to 14 days after the initiation of therapy.
Gastrointestinal Reactions: Epigastric distress, nausea,
vomiting and glossitis.
Hematologic Reactions: Thrombocytopenia, leukopenia,
neutropenia, megaloblastic anemia
and methemoglobinemia.
Metabolic Reactions: Hyperkalemia, hyponatremia.
Miscellaneous Reactions: Fever, elevation
of serum transaminase
and bilirubin and
increases in BUN and serum
creatinine levels.
DRUG INTERACTIONS
Trimethoprim may inhibit the hepatic
metabolism of phenytoin.
Trimethoprim, given at a common clinical
dosage, increased the
phenytoin half-life
by 51% and decreased the phenytoin
metabolic clearance
rate by 30%. When administering
these drugs concurrently, one should be alert for possible excessive
phenytoin effect.
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