Pharmacy & Therapeutics - November 2008 - (Page 672)

Pharmaceutical Approval Update (RBC) and white blood cell (WBC) abnormalities. A CBC, including platelet counts and peripheral blood smears, should be obtained weekly during the dose-adjustment phase of therapy, then monthly after a stable romiplostim dose is established. A CBC with platelet counts should be obtained each week for at least two weeks after discontinuation of romiplostim. Distribution: Romiplostim is available only through the romiplostim NEXUS Program (Network of Experts Understanding and Supporting Romiplostim and Patients). Only registered health care providers and patients can prescribe, administer, and receive this drug. This program provides educational materials and a mechanism for the proper use of romiplostim. Prescribers must inform patients about the drug’s benefits and risks; have patients read the medication guide; encourage patients to ask questions; review, sign, and return the enrollment form; review the form; answer all questions; place the signed form in the patient’s record; and give a copy to the patient. Serious adverse events should be reported to the program’s call center (1-877-2831) or to the FDA’s MedWatch Program (1-800-FDA-1088). Dosage and Administration: Only clinicians enrolled in the NEXUS program may prescribe romiplostim. A CBC, including platelet counts and peripheral blood smears, should be obtained before and throughout therapy. CBCs, including platelet counts, should be monitored for at least two weeks after the drug is discontinued. The lowest dose should be used to achieve and maintain a platelet count 50 × 109/L or higher, as necessary, to reduce the risk of bleeding. Romiplostim is given as a weekly subcutaneous injection only with a syringe containing 0.01-mL gradations. Dose adjustments are based on the platelet count response. This drug should not be used to normalize platelet counts. The prescribed dose may consist of a small volume (e.g., 0.15 mL). Initial dose: The initial dose is 1 mcg/kg based on the patient’s actual body weight. Dose adjustment: The patient’s body weight is used at the initiation of therapy. The weekly dose is then adjusted by increments of 1 mcg/kg until the patient achieves a platelet count of 50 × 109/L or more, as necessary, to reduce the risk of bleeding. A maximum weekly dose of 10 mcg/kg should not be exceeded. In clinical studies, most patients who responded to romiplostim achieved and maintained platelet counts of 50 × 109/L or greater with a median dose of 2 mcg/kg. During therapy, the CBC, as well as platelet counts and peripheral blood smears, should be obtained each week until the patient achieves a stable platelet count (50 × 109/L or greater for at least four weeks without a dose adjustment). A CBC, including a platelet count and a peripheral blood smear, is obtained each month thereafter. Doses are adjusted as follows: If the platelet count is below 50 × 109/L, the dose is increased by 1 mcg/kg. • If the platelet count is above 200 × 109/L for two consecutive weeks, the dose is reduced by 1 mcg/kg. • If the platelet count exceeds 400 × 109/L, no dose is given; the platelet count should be assessed weekly. • After the platelet count falls to below 200 × 109/L, therapy is resumed by a dose reduction of 1 mcg/kg. • Discontinuation: Romiplostim should be discontinued if the platelet count does not increase to a level sufficient to avoid clinically important bleeding after four weeks of romiplostim therapy at the maximum weekly dose of 10 mcg/kg. A CBC, including platelet counts, should be obtained weekly for at least two weeks after romiplostim is discontinued. Preparation: Romiplostim is supplied in single-use vials containing 250 or 500 mcg as a sterile, preservative-free, white lyophilized powder that must be reconstituted. Commentary: The estimated 140,000 patients with chronic ITP are prone to bruising and are at risk for life-threatening bleeding. Current treatments include corticosteroids and immunoglobulin. Surgery to remove the spleen may help some patients. Romiplostim is approved only for patients with chronic ITP who do not respond sufficiently to current treatments. It is the first product that directly stimulates bone marrow to produce needed platelets in patients with this rare blood disorder, which can lead to serious bleeding. Chronic ITP usually develops in adults and results in a low number of platelets. In patients with chronic ITP, it is thought that the immune system destroys platelets and that the patient’s bone marrow cannot compensate for this loss. Safety concerns include fibrous deposits in the bone marrow and the possibility that if romiplostim is stopped, the platelet count could fall below baseline levels. Additional risks include blood clots resulting from excessive increases in platelets. If romiplostim is given to patients with myelodysplasia, the risk of acute leukemia might increase. Myelodysplasia, which is associated with low platelet counts, predisposes some patients to leukemia. In one study, leukemia developed in four of 44 patients with myelodysplasia who received romiplostim. Romiplostim should be used only in patients with ITP whose degree of thrombocytopenia and whose clinical condition increase the risk of bleeding. This medication is not indicated for restoring platelet counts. Source: www.nplate.com Palonosetron HCl Capsules (Aloxi) Manufacturer: Eisai, Inc., Woodcliff Lake, N.J. Indication: Palonosetron is used to prevent chemotherapy-induced nausea and vomiting (CINV) associated with initial and subsequent courses of moderately emetogenic chemotherapy and to prevent acute nausea and vomiting associated with initial and repeated courses of highly emetogenic chemotherapy. Drug Class: This agent is a serotonin subtype-3 (5-HT3) receptor antagonist with a strong binding affinity for this receptor and with little or no affinity for other receptors. The empirical formula is C19H24N2O • HCl, and the molecular weight is 332.87. Palonosetron HCl exists as a single isomer. Uniqueness of Product: Cancer chemotherapy may be associated with a high incidence of nausea and vomiting. Serotonin receptors are located on the nerve terminals of the vagus in the periphery and centrally in the chemoreceptor trigger zone of the area postrema. It is thought that chemotherapeutic agents produce nausea and vomiting by releasing serotonin from the enterochromaffin cells of the small intestine and that the released serotonin then activates 5-HT3 receptors 672 P&T® • November 2008 • Vol. 33 No. 11 http://www.nplate.com

Table of Contents Feed for the Digital Edition of Pharmacy & Therapeutics - November 2008

Pharmacy & Therapeutics - November 2008 Contents Editorial Medication Errors Prescription: Washington New Drugs/Drug News/New Medical Devices Drug Forecast Heparin-Induced Thrombocytopenia Medication Utilization Patterns and Hypertension-Related Expenditures among Patients Who Were Switched From Fixed-Dose to Free-Combination Antihypertensive Therapy European Society for Medical Oncology and Association for the Study of Bone and Mineral Research Pharmaceutical Approval Update

Pharmacy & Therapeutics - November 2008

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