Dolasetron Mesylate

 Action Selective serotonin (5–HT3) receptor antagonist that inhibits serotonin receptors in the GI tract and chemoreceptor zone.

 Indications Parenteral or oral: Prevention of nausea and vomiting associated with initial and repeat courses of emetogenic chemotherapy; prevention of postoperative nausea and vomiting in patients at risk. Parenteral only: Treatment of postoperative nausea and vomiting. Unlabeled use(s): Radiotherapy-induced nausea and vomiting.

 Contraindications Standard considerations.

 Route/Dosage

Prevention of Chemotherapy-Induced Nausea and Vomiting

ADULTS & CHILDREN > 16 YR: PO 100 mg within 1 hr before chemotherapy. IV 1.8 mg/kg (or 100 mg) infused rapidly over 30 seconds or diluted and infused over 15 min, 30 min before chemotherapy. CHILDREN 2–16 YR: PO 1.8 mg/kg (maximum of 100 mg) within 1 hr before chemotherapy. IV 1.8 mg/kg (maximum of 100 mg) infused rapidly over 30 seconds or diluted and infused over 15 min, 30 min before chemotherapy.

Prevention of Postoperative Nausea and Vomiting in Patients at Risk

ADULTS & CHILDREN > 16 YR: PO 100 mg within 2 hrs before surgery. IV 12.5 mg 15 min before cessation of anesthesia. CHILDREN 2–16 YR: PO 1.2 mg/kg (maximum of 100 mg) within 2 hr before surgery. IV 0.35 mg/kg (maximum of 12.5 mg) 15 min before cessation of anesthesia.

Treatment of Postoperative Nausea and Vomiting

ADULTS & CHILDREN > 16 YR: IV 12.5 mg as a single dose as soon as nausea and vomiting presents. CHILDREN 2–16 YR: IV 0.35 mg/kg as a single dose as soon as nausea and vomiting present.

 Interactions

Drugs which prolong the QTc interval (eg, quinidine, etc): Additive effects on conduction. Atenolol: Increased serum levels of active metabolite (IV only). Cimetidine: Increased serum levels of active metabolite. Rifampin: Decreased serum levels of active metabolite.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Tachycardia; bradycardia; flushing; hypertension; hypotension. CNS: Headache; vertigo; dizziness agitation; drowsiness; sleep disorder; depersonalization. DERM: Rash; itching; sweating. GI: Abdominal pain; constipation; diarrhea; dyspepsia; anorexia; taste perversion; abnormal liver function. GU: Oliguria; urinary retention. OTHER: Fever; fatigue; pain; chills; shivering.

 Precautions

Pregnancy: Category B. Lactation: Undetermined. Children: Safety and efficacy in children < 2 yr not established. ECG Changes: Can cause ECG interval change (PR, QTc, JT) prolongation and QRS widening) which could cause cardiovascular consequences, including heart block and arrhythmias. These changes are related in magnitude and frequency to the active metabolite. Conditions predisposing to prolongation of cardiac conduction intervals (eg, electrolyte abnormalities, class 1A antiarrhythmias, etc): Use with caution.

 Administration/Storage

• Administer oral dose without regard to food.
• Dolasetron injection may be mixed with apple or apple-grape juice for oral administration in pediatric patients. Use within 2 hrs of dilution.
• Dolasetron injection can be infused IV as rapidly as 100 mg/30 seconds or diluted in 50 ml of a compatible IV solution and infused over a period of up to 15 min.
• Compatable IV fluids include: NS, D5W, D5W½NS, D5LR, LR and 10% mannitol injection.
• Do not mix dolasetron injection with solution for which compatibility has not been established.
• Do not mix dolasetron injection with other drugs.
• Flush infusion line before and after administration of dolasetron injection.
• Inspect injectable solutions for particulate matter or discoloration before use.
• Diluted injection is stable for 24 hrs at room temperature or for 48 hr if refrigerated.
• Store tablets and undiluted injection at room temperature protected from light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note risk factors which can cause ECG interval changes.
• Assess patient for nausea, vomiting and side effects.
• Monitor I & O carefully.
• Be prepared to give additional IV fluids to patient who is vomiting but do not overhydrate.

 Patient/Family Education

• Advise patient that headache is common side effect.
• Advise patient that medication will greatly reduce likelihood of nausea and vomiting but that these are still possible.