Beware of erroneous daily oral methotrexate dosing from Institute for Safe Medication Practices

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Beware of erroneous daily oral methotrexate dosing

PROBLEM: The perils of low-dose oral methotrexate are clearly evident in the

dozens of fatalities reported in patients who have been prescribed this

cytotoxic agent for alternative conditions. While methotrexate has a

well-established role in oncology, increasingly it's being used in low doses

for immunomodulation in rheumatoid arthritis, asthma, psoriasis,

inflammatory bowel disease, myasthenia gravis, and inflammatory myositis.

Used for these purposes, it's administered as a weekly dose. But mistakes

have been all too frequent because relatively few medications are dosed in

this manner and clinicians and patients are much more familiar with daily

dosing of medications. For example, one patient died after he misunderstand

the directions for use and took methotrexate 2.5 mg every 12 hours for six

consecutive days, instead of 2.5 mg every 12 hours for three doses each

week. Another patient died after he misread the directions on a prescription

bottle and took 10 mg every " morning " instead of every " Monday. " Errors also

have been reported with hospitalized patients. In one case, the physician

had properly recorded that the patient had been taking methotrexate 7.5 mg

weekly as an outpatient. But when he prescribed three 2.5 mg tablets weekly,

it was transcribed incorrectly as three times daily. Upon transfer to

another unit, the dose was transcribed incorrectly as three times a week. In

each case the errors did not reach the patient because they were detected

during pharmacy review of the order. Similar errors have been reported

overseas. For example, in Australia, one patient took extra doses of

methotrexate as needed to relieve arthritic symptoms. Three elderly patients

took the medication daily despite clearly written instructions to take it

weekly. Two cases involved incorrect transcription of the dosing schedule

with hospitalized patients. Three of the six patients died as a result of

the errors.

SAFE PRACTICE RECOMMENDATION: Because of the number of fatalities from

errors with oral methotrexate, clinicians should consider it a high alert

medication. As such, there are several measures that can help reduce the

risk of an error when oral methotrexate is prescribed:

* Build alerts in electronic prescribing systems and pharmacy computers

to warn clinicians whenever doses of oral methotrexate have been entered

(and to remind staff to check the indication with the patient in a retail

setting). Configure the systems to avoid defaulting to a daily dosing

schedule.

* Have a pharmacist conduct a prospective drug utilization review before

dispensing oral methotrexate to determine its indication for use, verify

proper dosing, confirm the correct dosing schedule on medication

administration records and prescription labels, ensure staff and patient

education, and promote appropriate monitoring of the patient.

* Establish a system that ensures that outpatients 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).

* Provide patients with clear written instructions that name a specific

day of the week for taking the tablet(s). When possible avoid choosing

Monday since it could be misread as " morning. " Prepare instructions in big

print to assist elderly patients with poor eyesight.

* Advise patients to contact their physician if they miss taking a dose.

Tell them that a flare-up of the disease is unlikely with one missed dose.

* Ensure that written drug information leaflets are given to patients

and that they contain clear advice about the weekly dosage schedule, not a

daily dosing schedule.

* Explain to patients that taking extra doses is dangerous. Encourage

feedback to ensure that the patient understands the weekly dosing schedule

and that the medication should not be used " as needed " for symptom control.

* Solicit help from a responsible caregiver if the patient appears to

have cognitive or severe sensory difficulties.

* Prescribe the drug as a dose pack (e.g., RHEUMATREX by Lederle), which

helps to reinforce the weekly dosing schedule.

http://www.ismp.org/MSAarticles/Beware.htm