DOLASETRON MESYLATE

DOLASETRON MESYLATe
(dol-a-se'tron)
Anzemet
Classifications: antiemetic; selective serotonin (5-ht₃) receptor antagonist;
Therapeutic: antiemetic
Prototype: Ondansetron
Pregnancy Category: B

Availability

50 mg, 100 mg tablets; 20 mg/mL injection

Action

Dolasetron is a selective serotonin (5-HT₃) receptor antagonist used for control of nausea and vomiting associated with cancer chemotherapy. Serotonin receptors affected by dolasetron are located in the chemoreceptor trigger zone (CTZ) of the brain and peripherally on the vagal nerve terminal. Serotonin, released from the cells of the small intestine, activate 5-HT₃ receptors located on vagal efferent neurons, thus initiating the vomiting reflex. Dolasetron causes ECG changes lasting from 6 to 24 h.

Therapeutic Effect

Has antiemetic properties that help patients on chemotherapy.

Uses

Prevention of nausea and vomiting from emetogenic chemotherapy, prevention and treatment of postoperative nausea and vomiting.

Contraindications

Hypersensitivity to dolasetron. Safety and efficacy in children <2 y are not established.

Cautious Use

Patients who have or may develop prolongation of cardiac conduction intervals, particularly QT_c (i.e., patients with hypokalemia, hypomagnesemia, diuretics, congenital QT syndrome; patients taking antiarrhythmic drugs and high-dose anthracycline therapy, etc.), pregnancy (category B), and lactation.

Route & Dosage

Prevention of Chemotherapy-induced Nausea and Vomiting
Adult/Child (>2 y): IV 1.8 mg/kg or 100 mg administered 30 min prior to chemotherapy (not more than 100 mg/dose) PO 100 mg 1 h prior to chemotherapy

Pre-/Postoperative Nausea and Vomiting
Adult: IV 12.5 mg 15 min before cessation of anesthesia or when post-op nausea and vomiting occurs PO 100 mg within 2 h prior to surgery
Child (>2 y): IV 0.35 mg/kg up to 12.5 mg 15 min before cessation of anesthesia or when post-op nausea and vomiting occurs PO 1.2 mg/kg up to 100 mg starting 2 h prior to surgery (may also mix IV formulation in apple or apple-grape juice and administer orally)

Administration

Oral

Give dissolved in apple or apple-grape juice 1 h before chemotherapy.
Give within 2 h before surgery, when used for post-op nausea.

Intravenous

PREPARE: Direct: Give undiluted. IV Infusion: Dilute in 50 mL of any of the following: NS, D5W, D5/0.45% NaCl, LR.

ADMINISTER: Direct: Inject undiluted drug over 30 sec. IV Infusion: Infuse diluted drug over 15 min.

INCOMPATIBILITIES Solution/additive: Potassium chloride.

Store at 20°–25° C (66°–77° F) and protect from light.
Diluted IV solution may be stored refrigerated up to 48 h.

Adverse Effects (≥1%)

Body as a Whole: Fever, fatigue, pain, chills or shivering. CNS: Headache, dizziness, drowsiness. CV: Hypertension. GI: Diarrhea, increased LFTs, abdominal pain. Genitourinary: Urinary retention.

Interactions

Drugs: Avoid use with apomorphine due to hypotension; ziprasidone may prolong QT interval.

Pharmacokinetics

Absorption: Rapidly absorbed from GI tract. Peak: 0.6 h IV, 1 h PO. Distribution: Crosses placenta, distributed into breast milk. Metabolism: Metabolized to hydrodolasetron by carbonyl reductase. Hydrodolasetron is metabolized in the liver by CYP2D6. Elimination: Primarily in urine as hydrodolasetron. Half-Life: 10 min dolasetron, 7.3 h hydrodolasetron.

Nursing Implications

Assessment & Drug Effects

Therapeutic effectiveness: Prevention of nausea and vomiting.
Determine serum electrolytes before initiating drug. Hypokalemia and hypomagnesemia should be correct before initiating therapy.
Monitor closely cardiac status especially with vomiting, excess diuresis, or other conditions that may result in electrolyte imbalances.
Monitor ECG, especially in those taking concurrent antiarrhythmic or other drugs that may cause QT prolongation.
Monitor for and report signs of bleeding (e.g., hematuria, epistaxis, purpura, hematoma).
Lab tests: With prolonged therapy, periodically monitor liver functions, PTT, CBC with platelet count, and alkaline phosphatase.

Patient & Family Education

Headache requiring analgesic for relief is a common adverse effect.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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