Download I Can PresCribE A Drug: Mnemonic

236
April 2007
Family Medicine
For the Office-based Teacher of Family Medicine
William Huang, MD
Feature Editor
Editor’s Note: In this month’s column, Karl Iglar, MD; Natalie Kennie, PharmD; and Jana Bajcar,
MScPharm, EdD, of St Michael’s Hospital and the University of Toronto, present the I Can PresCribE
A Drug mnemonic, which summarizes the systematic approach to prescribing that they teach their
residents. Office-based teachers can similarly use this approach to help residents and students select
the most approprate medication for their patients.
I welcome your comments about this feature, which is also published on the STFM Web site at www.
stfm.org. I also encourage all predoctoral directors to make copies of this feature and distribute it to their
preceptors (with the appropriate Family Medicine citation). Send your submissions to williamh@bcm.
tmc.edu. William Huang, MD, Baylor College of Medicine, Department of Family and Community
Medicine, 3701 Kirby, Suite 600, Houston, TX 77098-3926. 713-798-6271. Fax: 713-798-7789. Submissions should be no longer than 3–4 double-spaced pages. References can be used but are not required.
Count each table or figure as one page of text.
I Can PresCribE A Drug: Mnemonic-based Teaching
of Rational Prescribing
Karl Iglar, MD; Natalie Kennie, PharmD; Jana Bajcar, MScPharm, EdD
Rational prescribing refers to the
“selection of the most appropriate
therapeutic regimen for a specific
patient.”1 There is a need to teach
learners principles of rational prescribing since one study found that
medical students and residents often
do not perform important tasks such
as checking dosage calculations or
searching for possible drug-drug
interactions prior to writing a new
prescription.2 Further, prescribing
or prescription errors have been
discovered in as many as 11% of
all prescriptions in primary care.3
(Fam Med 2007;39(4):236-40.)
From the Department of Family and Community Medicine, St. Michael’s Hospital, Toronto,
and the Department of Family and Community
Medicine (all) and the Leslie Dan Faculty of
Pharmacy (Drs Kennie and Bajcar), University
of Toronto.
A previous survey found that only
38.5% of family medicine residency
programs offered a formal pharmacotherapy curriculum.4 More
recently, the Society of Teachers
of Family Medicine Group on
Pharmacotherapy has published
guidelines for a pharmacotherapy
curriculum that can be offered
during family medicine residency
training.5 Proper training in rational
pharmacotherapy does result in rational prescribing habits, at least in
the short term6 and therefore should
be an integral part of residency
curricula.
Several systematic approaches to
selection of pharmacotherapy have
been described in the literature.7-9
The World Health Organization
has published the Guide to Good
Prescribing that promotes a global
approach to rational prescribing.7
It includes creating a personal
formulary of effective medications
that are likely to be used frequently,
defining the problem (diagnosis),
specifying the therapeutic objective, ensuring that a medication
from the personal formulary has
proven efficacy and safety for
the patient under consideration,
informing the patient about the
treatment, and then monitoring
the results and stopping the drug
when the problem has resolved.
More recently, Bazaldua et al have
incorporated these same principles
including the consideration of nondrug therapy into the ESSEnCE
approach to rational prescribing.8 In
his description of a family medicine
residency curriculum on prescribing, Gaspar lists efficacy, convenience, safety, and cost as “rational
criteria” in choosing prescription
drugs.9 Not surprisingly, various
authors report similar components
that are important in the rational
prescribing process.
For the Office-based Teacher of Family Medicine
After focus groups of residents
and faculty identified a need to develop a systematic approach to drug
prescribing, the Family Medicine
Residency Program of St. Michael’s
Hospital, a fully-affiliated teaching
institution within the University of
Toronto, developed and adopted a
formal curriculum in 2001 focusing
on relevant pharmacotherapeutics
knowledge and medication prescribing skills. Since then, through the
therapeutics curriculum, residents
have learned a systematic approach
to prescribing, easily remembered
by the mnemonic, I Can PresCribE
A Drug, that isolates specific steps
that lead to an individualized selection of a medication for a specific
patient. This paper describes this
approach and the related medication knowledge that the learner
will need to consider at each step,
which will ideally lead to the best
medication being prescribed to a
specific patient. This tool can be
Vol. 39, No. 4
used by family medicine residents
during their residency training as
well as by medical students doing
their clinical rotations.
I Can PresCribE A Drug
Mnemonic
The mnemonic, comprised of
seven components related to rational prescribing, starts with the
learner creating a list of all potential
pharmacotherapeutic and nondrug
alternatives. This is followed by
a sequence of steps that systematically eliminate or retain certain
alternatives from the initial list. The
end result is a selection of the best
medication for a patient at a given
time. Table 1 shows how this mnemonic can be applied to a specific
patient situation and potential drug
information resources that can be
used or accessed by the learner to
acquire the pharmacotherapeutic
content for each step.
237
1. Indication
The first step is to identify the
diagnosis for the patient and decide
if therapy is indicated. The learner
must consider the general goals of
therapy as well as the needs and
expectations of the patient. The
learner may access therapeutic
information from clinical practice
guidelines as well as other available evidence from clinical trials
or systematic reviews. From this
evidence, the learner identifies all
potentially effective alternatives
for therapy, both drug and nondrug, and learns if medication is
indicated.
2. Contraindications
The second step is to determine
if any medications are absolutely
contraindicated and thus need to be
eliminated from the list of potential alternatives. This prompts the
learner to consider drug allergies,
Table 1
Use of the I Can PresCribE A Drug Mnemonic
Case Scenario:
Mrs DM, a 67-year-old woman (weight 70 kg, ideal body weight 65 kg), presents with poorly controlled diabetes mellitus (A1c 8.4%). She is currently
treated with glyburide 10 mg by mouth twice per day. Her past medical history is significant for myocardial infarction complicated by congestive heart
failure 1 year ago (symptoms now stable). Her medications include: glyburide 10 mg twice per day, gemfibrozil 600 mg twice per day, ramipril 10 mg once
per day, aspirin 81 mg once per day, Furosemide 40 mg once per day.
Mnemonic Components
Indication
I
C
a
n
Contraindications
Case Example Description
Treatment is indicated to achieve optimal control of glycemia of an
A1c < 7%. In this case, the patient is currently taking glyburide at a
maximum dose, and combination therapy is recommended from clinical
practice guidelines, along with lifestyle changes. (Information such as
this can be found in recent evidence-based clinical practice guidelines
on diabetes mellitus.11-13 )
Potential therapeutic available alternatives to choose from include:
• biguanides (eg, metformin)
• glitazones (eg, pioglitazone, rosiglitazone)
• α-glucosidase inhibitors (eg, acarbose)
• insulin secretagogues (eg, nateglinide, repeglinide)
• insulin
Due to this patient’s history of congestive heart failure, one can
eliminate glitazones as a potential choice.12,16,17
(continued on next page)
Potential Resource Type
• Evidence from clinical trials
• Evidence-based clinical practice guidelines
• Evidence from systematic reviews
(including Cochrane reviews14 or Clinical
Evidence reviews15)
• Drug product monographs, including those
from:
• Published drug information references16-17
• Electronic drug information databases
such as Epocrates®,18 Lexi-comp,19 and
Micromedex® Healthcare Series20
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April 2007
Family Medicine
Table 1
(continued)
Mnemonic Components
Precautions
P
r
e
s
C
r
i
b
E
Case Example Description
Pregnancy and lactation as a precaution is not applicable in this case.
Potential Resource Type
• Resources on medications during
pregnancy and lactation (eg, Briggs et al.
Laboratory indices that should be performed prior to drug therapy include Drugs in Pregnancy and Lactation21 )
a serum creatinine and liver enzymes.
• Drug product monographs from
published drug information references
Potential drug-drug interactions should be considered. In this case, one
or electronic drug information databases
can eliminate repaglinide (a short-acting secretagogue) as a potential
noted above
choice, since when used in combination with gemfibrozil, it may cause
• Drug interaction references including:
16,17
severe and prolonged hypoglycemia.
• Published references22,23
• Electronic drug information
databases18-20
Cost/
Compliance
• Drug benefit or managed care
In consulting drug benefit formularies, one may eliminate some
alternatives due to their excessive cost. For example, acarbose and insulin formularies
secretagogues may have limited coverage based on specific criteria.
• Drug product monographs from
published drug information references
One may rule out the use of insulin at this stage since the need for
or electronic drug information databases
subcutaneous administration is inconvenient for the patient and has the
noted above
potential to lead to noncompliance.
Efficacy
One can rule out acarbose at this stage as it usually produces only a
mean decrease in A1c of 0.5% to 0.8%, which is inadequate for this case
scenario.12,13
Other oral hypoglycemic alternatives such as insulin secretagogues
and metformin are likely to produce an average A1c lowering of 1.0%
to 1.5%.12 Use of drug classes with similar mechanisms of action
(eg, sulfonylureas and insulin secretagogues) is less effective than
combination therapy with agents that have different mechanisms of
action.13 For this reason, use of insulin secretagogues such as nateglinide
can be ruled out at this stage.
• Evidence from clinical trials
• Evidence-based clinical practice
guidelines
• Evidence from systematic reviews
(including Cochrane reviews14 or Clinical
Evidence reviews15)
Metformin, when used in obese patients, may improve cardiovascular
outcomes, which would be of further benefit for this patient.24 At this
stage, one realizes that metformin is a good option.
Fasting blood glucose and A1c will need to be monitored to determine the
effectiveness of drug therapy.
Adverse effects
A
Potential common and serious side effects for potential treatment
alternatives are considered, discussed with the patient, and monitored.
For example, with metformin, a common side effect is gastrointestinal
intolerance, while more-serious but rare side effects include
hypoglycemia and lactic acidosis.16,17
• Drug product monographs from
published drug information references
or electronic drug information databases
noted above
• Adverse drug reaction reports (such as
US Food and Drug Administration Safety
Alerts25)
Considering the step-wise process above, metformin is determined as the most appropriate alternative for this case, as other therapeutic alternatives have
been ruled out.
D
r
u
g
Dose/Duration/
Direction
An appropriate starting dose for this patient would be metformin
• Drug product monographs from published
500–1,000 mg orally each day and titrate by 500 mg increments every drug information references or electronic
7 days if home blood sugar readings remain high, to a maximal dose of drug information databases noted above
2,500 mg/day based on efficacy and tolerability.16,17
For the Office-based Teacher of Family Medicine
major organ disease (eg, renal or
hepatic, etc) or other concomitant
disease in a given patient that would
contraindicate the use of each therapeutic option. Drug product monographs that can be found in written
references or electronic database
products can be useful resources
for this type of information.
decision and what parameters will
indicate that the therapy being
considered is effective. On many
occasions, the learner may also
consult applicable evidence from
clinical trials, systematic reviews,
or clinical practice guidelines to
ensure the most efficacious medication is chosen.
3. Precautions
The evaluation of precautions
has three distinct steps that may
lead to further reducing the list
of potential alternatives. First, the
learner considers if the patient is
pregnant or lactating. Second, the
learner is asked to determine if
there are any laboratory indices that
need to be assessed prior to starting
therapy to ensure that all potential
precautions have been considered.
Third, the learner considers the
patient’s medical history and other
drug therapy the patient may be
taking to ascertain if there are any
significant drug-disease or drugdrug interactions with the therapeutic option in question. Drug
product monographs can be useful
for this step as well as specialized
resources on drug-drug interactions and the use of medications in
pregnancy and lactation.
6. Adverse Drug Effects
The learner then considers not
only the common adverse drug reactions a patient may encounter as
a result of the therapy but also the
potentially serious side effects that
could further influence the choice
of drug therapy. Drug product
monographs from written references or electronic databases are
useful resources for this step.
At this point in the stepwise
process, the learner has narrowed
down the choice to the best possible
pharmacotherapeutic alternative
and is ready to proceed with step
7.
4. Cost/Compliance
This step prompts the learner
to inquire about drug coverage
the patient possesses and whether
the therapeutic option is covered.
The learner should also determine
the cost of the medications being
considered and consider which
drug formulation allows for better
compliance or easier administration, such as those that minimize
the frequency of dosing.
5. Efficacy
The learner now must consider
the efficacy of treatment and compare the relative efficacy of the
alternatives that remain as potential
choices. In this step, the learner
considers whether there are any
patient-related factors relating to
efficacy that could influence the
7. Dosage/Duration/Direction
The learner must determine the
appropriate dosage, duration of
therapy, and any additional directions for the specific patient scenario. Drug product monographs from
written references or electronic
databases are potential resources
for this step.
Once the appropriate therapy is
selected, the mnemonic can serve
as a communication framework
when discussing the rationale for
therapy with a patient. Failure to
consider or inform patients of important aspects of new medications,
such as the name, purpose, adverse
effects, and duration of therapy,
may lead to nonadherence by the
patient.10
Discussion
Our I Can PresCribE A Drug
approach is complementary to
other approaches reported previously and provides an additional
framework that learners can use to
learn how to choose medications
for individual patients. In addition
Vol. 39, No. 4
239
to the key factors in medication
selection reported by others,7-9 our
approach emphasizes that learners consider all possible effective
pharmacotherapeutic alternatives
and also explicitly reminds them to
address issues such as contraindications and precautions. By going
through each step of this approach
and including or excluding medications based on individual patient
factors, the learner will arrive at
the most suitable medication for the
patient and also be able to explain
to the patient why that medication
was selected.
The I Can PresCribE A Drug
mnemonic has served as a useful framework for delivering a
pharmacotherapeutics curriculum
to family medicine residents at
St. Michael’s Hospital, Toronto.
When discussing specific patients
and their need for drug therapy,
office-based teachers of family
medicine can use this approach
to help students or residents learn
how to select the most appropriate
medication for the patient.
Corresponding Author: Adress correspondence
to Dr Iglar, 30 Bond Street, Toronto, Ontario
M5B 1W8, Canada. 416-360- 4000, ext. 8013.
Fax: 416-867-7498. [email protected].
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