Download Acetazolamide Acetazolamide sodium

Acetazolamide
IV
E
(ah -set-ah -Z O E- la- my d)
CLASSIFICATION(S):
Anticonvulsant, carbonic anhydrase
inhibitor
PREGNANCY CATEGORY: C
WRx: Apo-Acetazolamide.
Acetazolamide
sodium
Rx: Acetazolamide sodium
SEE ALSO ANTICONVULSANTS AND
DIURETICS, CHAPTER 2.
USES
(1) Adjunct in the treatment of edema
due to CHF or drug-induced edema. (2)
Absence (petit mal), especially in children) and unlocalized seizures. (3)
Open-angle, secondary, or acute-angle
closure glaucoma when delay of surgery is desired to lower IOP. (4) Prophylaxis or treatment of acute mountain
sickness in climbers attempting a rapid
ascent or in those susceptible to mountain sickness even with gradual ascent.
ACTION/KINETICS
Action
Sulfonamide derivative possessing carbonic anhydrase inhibitor activity. Anticonvulsant effects may be due to (1)
inhibition of carbonic anhydrase in the
CNS, which increases carbon dioxide
tension resulting in a decrease in neuronal conduction, and (2) systemic acidosis. As a diuretic, the drug inhibits
carbonic anhydrase in the kidney,
which decreases formation of bicarbonate and hydrogen ions from carbon dioxide, thus reducing the availability of
these ions for active transport. Use as a
diuretic is limited because the drug promotes metabolic acidosis, which inhibits diuretic activity. This may be partially
circumvented by giving acetazolamide
on alternate days. Also reduces intraocular pressure.
Pharmacokinetics
Absorbed from the GI tract and widely
distributed throughout the body, including the CNS. Tablets: Onset, 60–90
Bold Italic = life threatening side effect
min; peak: 1–4 hr; duration: 8–12 hr.
Sustained-release capsules: Onset, 2
hr; peak: 3–6 hr; duration: 18–24 hr.
Injection (IV): Onset, 2 min; peak: 15
min; duration: 4–5 hr. Eliminated mainly unchanged through the kidneys.
CONTRAINDICATIONS
Low serum sodium and potassium levels. Renal and hepatic dysfunction. Hyperchloremic acidosis, adrenal insufficiency, suprarenal gland failure, hypersensitivity to thiazide diuretics, cirrhosis.
Chronic use in noncongestive angleclosure glaucoma.
SPECIAL CONCERNS
• Use with caution in the presence of
mild acidosis, advanced pulmonary
disease, and during lactation.
• Increasing the dose does not increase effectiveness but may increase the risk of drowsiness or
paresthesia.
• Safety and efficacy not established in
children.
SIDE EFFECTS
Most Common
Anorexia, dizziness, lightheadedness,
blurred vision, pruritus, GI upset, headache, weakness.
GI: Anorexia, GI upset, N&V, melena,
constipation, alteration in taste, diarrhea. GU: Hematuria, glycosuria, urinary
frequency, renal colic/calculi, crystalluria, polyuria, phosphaturia, decreased/
absent
libido,
impotence.
CNS:
Seizures, weakness, malaise, lightheadedness, fatigue, nervousness, drowsiness, depression, dizziness, disorientation, confusion, ataxia, tremor, headache, tinnitus, flaccid paralysis, lassitude, paresthesia of the extremities.
Hematologic: Bone marrow depression,
thrombocytopenic
purpura,
thrombocytopenia, hemolytic anemia,
leukopenia, pancytopenia, agranulocytosis. Dermatologic: Pruritus, urticaria,
skin rashes, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, photosensitivity. Miscellaneous: Weight loss, weakness, fever, acidosis, electrolyte imbalance, transient myopia, blurred vision, hepatic
insufficiency. NOTE: Side effects similar
to those produced by sulfonamides
may also occur.
■ = black box warning
W = Available in Canada
OD OVERDOSE MANAGEMENT
Symptoms: Drowsiness, anorexia, N&V,
dizziness, ataxia, tremor, paresthesias,
tinnitus. Treatment: Emesis or gastric lavage. Hyperchloremic acidosis may respond to bicarbonate. Administration
of potassium may also be necessary.
Observe carefully and give supportive
treatment.
DRUG INTERACTIONS
SEE ALSO DIURETICS
Amphetamine / 앖 Amphetamine effect
by 앖 renal tubular reabsorption
Cyclosporine / 앖 Cyclosporine levels 씮
possible nephrotoxicity and neurotoxicity
Diflunisal / Significant 앗 in IOP with 앖
side effects
Ephedrine / 앖 Ephedrine effect R/T 앖
renal tubular reabsorption
Lithium carbonate / 앗 Lithium effect
R/T 앖 renal excretion
Methotrexate / 앗 Methotrexate effect
R/T 앖 renal excretion
Primidone / 앗 Primidone effect R/T 앗
GI absorption
Pseudoephedrine / 앖 Pseudoephedrine
effect by 앖 renal tubular reabsorption
Quinidine / 앖 Quinidine effect by 앖
renal tubular reabsorption
Salicylates / Accumulation and toxicity
of acetazolamide (including CNS depression and metabolic acidosis). Also,
acidosis due to 앖 CNS penetration of
salicylates
HOW SUPPLIED
Acetazolamide: Capsules, Extended-Release: 500 mg; Tablets: 125 mg, 250 mg.
Acetazolamide sodium: Powder for Injection: 500 mg.
DOSAGE
• CAPSULES, EXTENDED-RELEASE; IV;
TABLETS
Diuresis in CHF.
Adults, initial: 250–375 mg (5 mg/kg)
once daily in the morning. If the client
stops losing edema fluid after an initial
response, do not increase doses; rather,
skip medication for a day to allow the
kidney to recover. The best diuretic effect occurs when the drug is given on
alternate days or for 2 days alternating
with a day of rest.
Drug-induced edema.
Adults: 250–375 mg once daily for 1 or
2 days. Most effective if given every
C = see color insert
H = Herbal
other day or for 2 days followed by a
day of rest. Children: 5 mg/kg/dose PO
or IV once daily in the morning.
Absence and unlocalized seizures.
Adults/children: 8–30 mg/kg/day in divided doses. Optimum daily dosage:
375–1,000 mg (doses higher than 1,000
mg do not increase therapeutic effect).
Adjunct to other anticonvulsants.
Initial: 250 mg/day; dose can be increased up to 1,000 mg/day in divided
doses if necessary.
Glaucoma, simple open-angle.
Adults: 250–1,000 mg/day in divided
doses. Doses greater than 1,000 mg/day
do not increase the effect.
Glaucoma, secondary or acute congestive (closed-angle).
Adults, short-term therapy: 250 mg q
4 hr or 250 mg twice a day. Adults,
acute therapy: 500 mg followed by
125–250 mg q 4 hr using tablets. For
extended-release capsules, give 500 mg
twice a day in the morning and evening. IV therapy may be used for rapid
decrease in intraocular pressure. Pediatric: 5–10 mg/kg/dose IM or IV q 6 hr
or 10–15 mg/kg/day in divided doses q
6–8 hr using tablets.
Acute mountain sickness.
Adults: 500 mg 1–2 times per day of
tablets or extended-release capsules.
During rapid ascent, 1,000 mg/day is
recommended.
NURSING CONSIDERATIONS
E Do not confuse acetazolamide with
acetohexamide (oral antidiabetic).
ADMINISTRATION/STORAGE
1. Changeover from other anticonvulsant therapy should be gradual.
2. Acetazolamide tablets may be
crushed and suspended in a cherry,
chocolate, raspberry, or other sweet syrup. Do not use vehicles containing glycerin or alcohol.
3. Tolerance after prolonged use may
necessitate dosage increase.
4. Do not administer the extended-release dosage form as an anticonvulsant;
used only for glaucoma and acute
mountain sickness.
5. With mountain sickness prophylaxis,
initiate dosage 1–2 days before ascent
and continue for at least 2 days while at
high altitudes.
IV = Intravenous
E = sound alike drug
6. Due to possible differences in bioavailability, do not interchange brands.
IV 7. IV administration is preferred; IM
administration is painful due to alkalinity of solution.
8. For direct IV use, administer over at
least 1 min. For intermittent IV use, further dilute in dextrose or saline solution
and infuse over 4–8 hr. Reconstitute
each 500-mg vial with at least 5 mL of
sterile water for injection.
9. Refrigerate reconstituted solution at
28° C (36–46° F). Use within 12 hr; contains no preservative.
ASSESSMENT
1. Note reasons for therapy, onset/
characteristics of symptoms.
2. Review I&O, CBC, electrolytes, uric
acid, and glucose. Assess for liver/renal
dysfunction. Metabolic acidosis and
electrolyte imbalance may occur.
3. List drugs prescribed to ensure no
interactions.
4. With glaucoma, note baseline ophthalmic exam and intraocular pressures;
assess for visual effects.
5. Perform CV/pulmonary assessment
with CHF history. Obtain VS and weight.
CLIENT/FAMILY TEACHING
1. Taking drug with food may decrease
GI upset/irritation.
2. Assess drug effects before undertaking tasks that require mental alertness;
may cause drowsiness.
Bold Italic = life threatening side effect
3. Increases voiding frequency; take
early to avoid interrupting sleep.
4. Use only as directed. If prescribed
every other day, record to ensure
adherence.
5. Increase fluids (2–3 L/day) to prevent
urine crystals/stone formation.
6. May increase blood glucose levels.
Monitor FS and report increases; diabetes agent may need adjustment. Avoid
high-sodium foods.
7. Report if nausea, dizziness, rapid
weight gain, muscle weakness, cramps,
or any changes in the color/consistency
of stools occur.
8. Practice reliable contraception; may
cause fetal defects.
9. To avoid mountain sickness, gradual
ascent should occur. If rapid ascent is
undertaken and acetazolamide tablets
are used, such use does not obviate the
need for prompt descent if severe
forms of high altitude sickness occur,
i.e., high altitude pulmonary edema or
high altitude cerebral edema.
10. Avoid excess exposure to sunlight
to prevent photosensitivity reaction.
11. Keep all F/U to assess response,
labs (may need potassium replacement), and for adverse SE.
OUTCOMES/EVALUATE
• 앗 Seizure activity
• 앗 Intraocular pressure
• 앗 CHF-associated edema
• Prevention of mountain sickness
■ = black box warning
W = Available in Canada