Lowdown on lomustine: We’d hate CeeNU make this mistake

Problem: Last month we learned about three errors with lomustine (CeeNU) that sounded hauntingly similar to methotrexate errors we reported in our April 3, 2002 newsletter. When used to treat rheumatoid arthritis and other non-oncologic conditions, a single dose of oral methotrexate should be taken just once or twice a week. A single dose of oral lomustine (130 mg/m2), used to treat brain cancer and Hodgkin’s disease, should only be taken once every 6 weeks. Similar to methotrexate, lomustine has been repeatedly dispensed and administered daily, often with tragic results.

Two of the lomustine errors are recent. In one case, a cancer patient’s usual dose of lomustine 140 mg was due the day after she had been admitted to the hospital for a laparoscopic procedure. Her oncologist ordered a single dose of the drug, but the hospital pharmacist mistakenly entered it as a daily dose, which appeared on the nurse’s computer-generated medication administration record. Five days after receiving the drug daily, routine lab tests detected severe thrombocytopenia, azotemia, and neutropenia. By then, the patient was febrile with severe bruising and hematuria. The oncologist discovered the error, and after a prolonged hospitalization, the patient fortunately recovered.

Another recent error happened in a community pharmacy, where a patient presented with a prescription for a single 160 mg dose of lomustine. The pharmacist decided to offer the patient a full package containing 20 capsules (40 mg each), since the drug was costly and he would likely have to discard the remaining capsules. While the directions on the package correctly stated to take just four capsules, the patient misunderstood the instructions and took four capsules daily for 5 days. The error was discovered when the patient attempted to refill the prescription. The pharmacist contacted the oncologist, and the patient was admitted to the hospital where he apparently recovered, although the full effects of toxicity are still pending.

Several years ago, a 24-year-old woman with brain cancer died as a result of a lomustine overdose. A physician had written a poorly legible prescription for lomustine 190 mg every 6 weeks. The pharmacist misunderstood the directions as “daily for 6 weeks” and dispensed a 6-week supply of capsules with directions to take 190 mg daily. The patient’s physician had not explained how to take the medication, so the patient complied with the label directions and took 190 mg daily for 21 days. She was hospitalized with severe bone marrow suppression and acute bleeding, and died a month later.

Safe Practice Recommendation: Bristol-Myers Squibb has enhanced the labeling and the packaging of CeeNU. “Single Dose Only” is now printed in red on the label, and “Dispense Single Dose Only” is embossed on the cap of stock bottles. However, it’s clear in the more recent cases that these warnings were overlooked. A boxed warning in the package insert also states that the drug should not be administered more frequently than every 6 weeks; however, the warning could be overlooked as it is embedded within information about the potential risk for bone marrow depression. Thus, there are several other safeguards that should be considered with this high-alert medication:

Provide alerts. Program warning messages such as “single dose only” into order entry systems. Also configure the system to limit the quantity prescribed or dispensed to 300 mg or less for each prescription or order.

Use unit-of-use Dose Packs. Prepare patient prescriptions or doses using unit-of-use Dose Packs available from the manufacturer. Each 300 mg Dose Pack contains two 100 mg capsules, two 40 mg capsules, and two 10 mg capsules, with instructions for the pharmacist to select the correct patient dose (within 10 mg), place the capsules in a single vial, and affix the special patient label provided.

Enhance labels. When possible, present dosing frequency directions on patient labels and nursing medication administration records using bold font or all capital letters (e.g., CAUTION: SINGLE DOSE ONLY). Use large print to assist elderly patients with poor eyesight.

Provide patient counseling. Establish a system to ensure that patients receive counseling when picking up new prescriptions and refills (e.g., mark the bag with a red flag to alert clerical staff that counseling is required, not optional). Require the pharmacist to review the prescription label with the patient or caregiver, and to request verbal confirmation to ensure that the patient understands the dosing schedule.

Supply leaflets. Ensure that written drug information leaflets are given to patients and that they contain clear advice about the “single dose only” dosing schedule.

Require education. Provide pharmacists, technicians, and nurses who handle oral (and parenteral) chemotherapy with initial and ongoing education. Allow only certified oncology nurses to administer chemotherapy (oral and parenteral).