Lithostat

[lith´o-stat] trademark for a preparation of acetohydroxamic acid, a urease inhibitor used in treatment of kidney stones and urinary tract infections.

acetohydroxamic acid

(a-seet-oh-hye-drox-am-ik a-sid) acetohydroxamic-acid,

AHA

(trade name),

Lithostat

(trade name)

Classification

Therapeutic: anti infectives
Pharmacologic: urease inhibitors
Pregnancy Category: X

Indications

Adjunct therapy in chronic urea-splitting urinary tract infection.

Action

Reversibly inhibits the bacterial enzyme urease, which results in decreased hydrolysis of urea and subsequent production of ammonia in urine infected with urea-splitting bacteria.

Therapeutic effects

Decreased urinary ammonia levels and decreased urine pH, which increases the efficacy of anti-infective therapy and cure rates.Does not directly alter pH or have any direct antibacterial activity.

Pharmacokinetics

Absorption: Well absorbed following oral administration.Distribution: Distributed throughout body water.Metabolism and Excretion: 36–65% excreted unchanged in urine.Half-life: 5–10 hr (increased in renal impairment).

Time/action profile (effect on urine)

ROUTE	ONSET	PEAK	DURATION
PO	4–8 hrs	0.25–1 hr†	6–8 hr

†Blood levels

Contraindications/Precautions

Contraindicated in: Urinary tract infection with non-urea-splitting organisms; Urinary tract infections that can be controlled by culture-specific oral antibiotics; Serum creatinine >2.5 mg/dL or CCr <20 mL/min; Obstetric: Causes birth defects; women of childbearing potential must use adequate contraception; Lactation: Safety not established.Use Cautiously in: Renal impairment (increased risk of adverse reactions; dosage reduction recommended); Hepatic impairment; Pre-existing thrombophlebitis or phlebothrombosis (increased risk of adverse reactions).

Adverse Reactions/Side Effects

Central nervous system

headache (most frequent)
anxiety (most frequent)
depression (most frequent)
malaise (most frequent)
nervousness (most frequent)
tremulousness (most frequent)

Cardiovascular

palpitations
superficial phlebitis of the lower extremities

Dermatologic

alopecia
rash (in association with alcohol)

Gastrointestinal

anorexia, (most frequent)
nausea, (most frequent)
vomiting (most frequent)

Hematologic

anemia (most frequent)
hemolytic anemia (most frequent)

Interactions

Drug-Drug interaction

Decreases absorption of iron.Iron decreases the absorption of acetohydroxamic acid.Concurrent ingestion of alcohol increases the incidence of rash.

Route/Dosage

Oral (Adults) 250 mg 3–4 times daily (total dose 10–15 mg/kg/day)(maximum daily dose = 1500 mg).Oral (Children) 10 mg/kg/day in divided doses; further titration may be necessary.

Renal Impairment

Oral (Adults) Serum creatinine 1.8–2.5 mg/dL—do not exceed 1000 mg/day (given at 12 hr intervals; further adjustments may be necessary).

Availability

Tablets: 250 mg

Nursing implications

Nursing assessment

Assess patient for signs and symptoms of urinary tract infection (frequency, urgency, fever, pus in urine) throughout therapy.
Lab Test Considerations: Monitor CBC including reticulocyte count after 2 wk of treatment and every 3 mo during therapy. Reticulocytosis and hemolytic anemia may occur. If reticulocyte count is >6%, reduce dose.
- Monitor renal and hepatic function closely during therapy.

Potential Nursing Diagnoses

Risk for infection (Indications)
Impaired urinary elimination (Indications)

Implementation

If a patient requires iron for a microcytic anemia, intramuscular iron can be used during the course of treatment with acetohydroxamic acid.
Oral: Administer on an empty stomach, 1 hr before or 2 hr after meals.

Patient/Family Teaching

Instruct patient to take medication exactly as directed.
Inform patient that mild headache may occur during first 48 hr of treatment. Headaches usually respond to oral salicylates (aspirin) and usually disappear spontaneously.
Advise patient that taking acetohydroxamic acid concurrently with alcohol may cause a nonpruritic macular skin rash to occur on upper extremities and face. Rash usually appears 30–45 min after ingestion of alcohol and may be associated with a sensation of warmth. It usually spontaneously disappears in 30–60 min.
Emphasize the importance of periodic lab tests to monitor for side effects.
Caution patients of childbearing potential to use a reliable form of contraception while taking acetohydroxamic acid.

Evaluation/Desired Outcomes

Decreased urinary ammonia levels and decreased urine pH which increases the efficacy of anti-infective therapy and cure rates in urinary tract infections.

Lithostat

(lĭth′ə-stăt′) A trademark for the drug acetohydroxamic acid.