Many doctors not only prescribe too much of a drug for too long, but also frequently too little of a drug for too long, but also frequently too little of a drug for too short a period. In one study about 10% of patients on benzodiazepines received them for a year or longer. Another study showed that 16% of outpatients with cancer still suffered from pain because doctors we afraid to prescribe morphine for a long period. They mistook tolerance for addiction. The duration of the treatment and the quality of drugs prescribed should also be effective and safe for the individual patient.
Overprescribing leads to many undesired effects. The patient receives unnecessary treatment, or drugs may lose some of their potency. Unnecessary side effects may occur. The quantity available may enable the patient to overdose. Drug dependence and addiction may occur. Some reconstituted drugs, such as eye drops and antibiotics syrups, may become contaminated. It may be very inconvenient for the patient to take so many drugs. Last, but not least, valuable and often scarce resources are wasted.
Underprescribing is also serious. The treatment is not effective, and
more aggressive or expensive treatment may be needed later. Prophylaxis may be
inconvenient to return for further treatment. Money spent on ineffective
treatment is money wasted.
Exercise: patients 21-28
For each of the following
cases verify whether the duration of treatment and total quantity of the drugs
are suitable (effective, safe). In all cases you may assume that the drugs are
your P-drugs.
Patient 21:
Woman, 56 years. Newly diagnosed depression. R/amitriptyline 25 mg, one
tablet daily at night, give 30 tablets.
Patient 22:
Child, 6 years. Giardiasis with persistent diarrhoea. R/metronidazole
200 mg/5 ml oral suspension, 5 ml three times daily, give 105 ml.
Patient 23:
Man, 18 years. Dry cough after a cold. R/codeine 30 mg, 1 tablet three
times daily, give 60 tablets.
Patient 24:
Woman, 62 years. Angina pecoris, waiting for referral to a specialist.
R/glyceryl trinitrate 5 mg, as necessary 1 tablet sublingual, give 60 tablets.
Patient 25:
Man, 44 years. Sleeplessness. Comes for a refill, R/diazepa, 5 mg, 1
tablet before sleeping, give 60 tablets.
Patient 26:
Girl, 15 years. Needs malaria prophylaxis for a two week trip to Ghana.
R/mefloquine 250 mg, 1 tablet weekly, give 7 tablets; start one week
before departure and continue four weeks after return.
Patient 27:
Boy, 14 years. Acute conjunctivities. R/tetracycline 0.5 % eye drops,
first 3 days every hour 1 drop, then 2 drops every six hours, give 10 ml.
Patient 28:
Woman, 24 years. Feels weak and looks a bit anaemic. No Hb result
available. R/ferrous sulfate 60 mg tablets, 1 tablet three times daily, give 30
tablets.
Patient 21 (depression)
A dose of 25 mg per day is probably insufficient to treat her
depression. Although she can start with such a low dose for a few days or a
week, mainly to get used to side effects of the drug, she may finally need
100-150 mg per day. With 30 tablets the quantity is sufficient for one month,
if the dosage is not changed before that time. But is it safe? At the
beginning of the treatment the effect
and side effects cannot be foreseen. And if the treatment has to be stopped,
the remaining drugs are wasted. The risk of suicide also has to be considered:
depressive patients are more liable to commit suicide in the initial stages of
treatment when they become more active because of the drug, but still feel
depressed. For these reasons 30 tablets are not suitable. It would be better to
start with 10 tablets, for the first week or so. If she reacts well you should
increase the dose.
Patient 22 (giardiasis)
With most infections time is needed to kill the microbes, and short
treatments may not be effective. However, after prolonged treatment the
micro-organisms may develop resistance
and more side effects will occur. In this patient the treatment is both
effective and safe. Giardiasis with persistent diarrhoea needs to be treated
for one week, and 105 ml is exactly enough for that period. Maybe it is even
too exact. Most pharmacists do not want to dispense quantities such as 105 ml
or 49 tablets. They prefer rounded figures, such as 100 ml or 50 tablets, because
calculating is easier and drugs are usually stocked or packed in such
quantities.
Patient 23 (dry cough)
The quantity of tablets is much too high for this patient. The
persistent dry cough prevents healing of the irritated bronchial tissue. Since
tissue can regenerate within three days the cough needs to be suppressed for
five days at most, so 10-15 tablets will be sufficient. Although a larger
quantity will not harm the patient, it is unnecessary, inconvenient and
needlessly expensive. Many prescribers would argue that no drug is needed at
all.
Patient 24 (angina)
For this patient the quantity is excessive. She will not use 60 tablets
before her appointment with the
specialist. And did you remember that the drug is volatile? After some
time the remaining tablets will no longer be effective.
Patient 25 (sleeplessness)
The diazepam refill for patient 25 is worrying. You suddenly remember
that he came for a similar refill recently and check the medical record. It was
two weeks ago! Looking more closely you find that he has used
diazepam four times daily for the last three years. This treatment has been
expensive, probably ineffective and has resulted in a severe dependency. You
should talk to the patient at the next visit and discuss with him how he can
gradually come off the drug.
Box 6: Repeat prescriptions in practice
In long-term treatment,
patient adherence to treatment can be a problem. Often the patient stops taking
the drug when the symptoms have disappeared or if side effects occur. For patients
with chronic conditions repeat prescriptions are often prepared by the
receptionist or assistant and just signed by the physician. This may be
convenient for doctor and patient but is has certain risks, as the process of
renewal becomes a routine, rather than a conscious act. Automatic refills are
one of the main reasons for overprescribing in industralized countries,
especially in chronic conditions. When patients live far away, convenience may
lead to prescriptions for longer
periods. This may also result in over prescribing. You should see your
patients on long-term treatment at least four times per year.
Patient 26 (malaria
prophylaxis)
There is nothing wrong with this prescription which follows the WHO
guidelines on malaria prophylaxis for traveller to Ghana. The dosage schedule
is correct, and she received enough tablets for the trip plus four weeks
afterwards. Apart from a small risk of drug resistance this drug treatment is
effective and safe.
Patient 27 (acute conjunctivitis)
The prescription of 10 ml eyedrops seems adequate, at first sight. In
fact, eyedrops are usually prescribed in bottles of 10 ml. But did you ever
check how many drops there are in a bottle of 10 ml? One ml is about 20 drops,
so 10 ml is about 200 drops. One drop every hour for the first three days means
3x24 = 72 drops. That leaves about 128 drops in the bottle. Two drops four
times per day for the remaining period is 8 drops a day. That is for another
130/8 = 16 days. The total treatment therefore covers 3 - 16 = 19 days! Yet, seven days
treatment at most should be enough for bacterial conjuctivitis. After some
arithmetic (72 + (4 x 8) = 104 drops = 104 x 0.05 = 5.2 ml) you conclude that 5
ml will be enough in future. This will also prevent any leftovers from being
used again without a proper diagnosis. Even more important, eyedrops become
contaminated after a few weeks, especially if they are not kept cool, and can
cause severe eye infections.
Patient 28 (weakness)
Did you notice that this is a typical example of a prescription without
a clear theapeutic objective? If the diagnosis is uncertain, the Hb should be
measure. If the patient is really anaemic she will need much more iron than the
ten days given here. She will probably need treatment for several weeks or
months, with regular Hb measurements in between.
Conclusion
Verifying whether your P-drug is also suitable for the individual
patient in front of you is probably the most important step in the process of
rational prescribing. It also applies if you are working in an environment in
which essential drugs lists, formularies and treatment guidelines exist. In
daily practice, adapting the dosage schedule to the individual patient is
probably the most common change that you will make.
Summary
Step 3: Verify that your
P-drug is suitable for this patient
3A Are the active substance and dosage form suitable?
Effective: Indication
(drug really needed)?
Convenience (easy to handle,
cost)?
Safe: Contraindications
(high risk groups, other diseases)?
3B Is the dosage schedule suitable?
Effective: Adequate
dosage (curve within window)?
Convenience (easy to memorize,
easy to do)?
Safe: Contraindications
(high risk groups, other diseases)?
Interactions (drugs, food,
alcohol)?
3C Is the duration suitable?
Effective: Adequate
duration (infections, prophylaxis, lead time)?
Convenience (easy to store,
cost)?
Safe: Contraindications
(side effects, dependence, suicide)?
Quantity too large (loss of
quality, use of leftovers)?
If necessary, change the
dosage form, the dosage schedule or the duration of treatment.
In some cases it is better
to change to another P-drug.
Exercise: Patient 29-32
Write a prescription for
each of the following patients. Prescriptions are discussed below.
Patient 29:
Boy, 5 years. Pneumonia with greenish sputum. Your P-drug is
amoxicillin syrup.
Patient 30:
Woman, 70 years. Moderate congestive cardiac failure. For several years
on digoxin 0.25 mg 1 tablet daily. She phones to ask for a repeat prescription.
As you have not seen her for some time you ask her to call. During the visit
she complains of slight nausea and loss of appetite. No vomiting or diarrhoea.
You suspect side effects of digoxin, and call her cardiologist. As she has an
appointment with him next week, and he is very busy, he advises you to halve
the dose until then.
Patient 31:
Woman, 22 years. New patient. Migraine with increasingly frequent
vomiting. Paracetamol no longer effective during attacks. You explain to her
that the paracetamol does not work because she vomits the drug before it is
absorbed. You prescribe paracetamol plus an anti-emetic suppository,
metoclopramide, which she should take first, and wait 20-30 minutes before
taking the paracetamol.
Patient 32:
Man, 53 years. Terminal stage of pancreatic cancer, confined to bed at
home. You visit him once a week. Today his wife calls and asks you to come
earlier because he is in considerable pain. You go immediately. He has slept
badly over the weekend and regular painkillers are not working. Together you
decide to try morphine for a week. Making sure not to underdose him, you start
with 10 mg every six hours, with 20 mg at night. He also has non-insulin
dependent diabetes, so you add a refill for his tolbutamide.
There is nothing wrong with any of the four prescriptions (Figures
6,7,8 and 9). However, a few remarks can be made. Repeat prescriptions, such as
the one for patient 30, are permitted. Many prescriptions are like that. But
they also need your full attention. Do not write a repeat prescription automatically!
Check how many times it has been repeated. Is it still effective? It is still safe? Does it
still meet the original needs?
For the opiate for patient 32, the strength and the
total amount have been written in words
so they cannot easily be altered. The
instructions are detailed and the maximum daily dose is mentioned. In some
countries it is mandatory to write an opiate prescription on a separate
prescription sheet.
Summary
A prescription should
include:
* Name, adress,
telephone of prescriber
* Date
* Generic name of the
drug, strength
* Dosage form, total
amount
* Label: instructions,
warning
* Name, address, age
of patient
* Signature or
initials of prescriber
Exercise: Patients 34-38
Review the following
prescriptions and list the most important instructions and warning that should
be given to the patient. You may consult your pharmacology books. Cases are discussed below.
Patient 34:
Man, 56 years. Newly diagnosed depression. R/amitriptyline 25 mg, 1
tablet daily at night for one week.
Patient 35:
Woman, 28 years. Vaginal trichomonas infection. R/metronidazole 500 mg,
1 vaginal tablet daily for 10 days.
Patient 36:
Man, 45 years. Newly diagnosed essential hypertension. R/atenolol 50
mg, 1 tablet daily.
Patient 37:
Boy, 5 years. Pneumonia. R/amoxicillin syrup, 5 ml (=250 mg) three
times daily.
Patient 38:
Woman, 22 years. Migraine. R/paracetamol 500 mg, 2 tablets 20 min.
after R/metoclopramide 10 mg 1 suppository, at the onset of an attack.
Patient 34 (depression)
It will take approximately two to three weeks before the patients
starts to feel better, but side effects, such as dry mouth, blurred vision,
difficulty in urinating and sedation, may occur quickly. Because of this many
patients think that the treatment is worse than the disease and stop taking the
drug. If they are not told that this may happen and that these effects
disappear after some time, adherence to treatment will be poor. For this reason
a slowly rising dosage schedule is usually chosen, with the tablets taken before
bedtime. This should be explained carefully to the patient. Older people,
especially, may not remember difficult dosage schedules. Write them down, or
give a medication box. You can also ask the pharmacist to explain it again
(write this on the prescription). Instructions are to follow the dosage
schedule, to take the drug at bedtime and not to stop the treatment. Warnings
are that the drug may slow reactions, especially in combination with alcohol.
Patient 35 (vaginal
trichomonas)
As in any infection the patient should be told why the course has to be
finished completely, even when the symptoms disappear after two days. The
patient should also be informed that treatment is useless if the partner is not
treated as well. Careful and clear instructions are needed for vaginal tablets.
If possible, pictures or leaflets should be used to show the procedure. Side
effects of metronidazole are a metal taste, diarrhoea or vomiting, especially
with alcohol, and dark urine. Give a clear warning against the use of alcohol.
Patient 36 (essential
hypertension)
The problem with the treatment of hypertension is that patients rarely
experience any positive effect of the drugs, yet they have to take them for a
long time. Adherence to treatment may be very poor if they are not told why
they should take the drug, and if treatment is not monitored regularly. The
patient should be told that the drug prevents complications of high blood
pressure (angina, heart attack, cerebral problems). You can also say that you
will try to decrease the dosage after three months, or even stop the drug
entirely. Remember to check whether the patient has a history of asthma.
Patient 37 (boy with
pneumonia)
The pacient´s mother should be told that the penicillin will need some
time to kill the bacteria. If the course of treatment is stopped too soon, the
stronger ones will survive, and cause a second, possibly more serious
infection. In this way she will understand why it is necessary to finish the
course. Knowing that any side effects will disappear soon will increase the
likelihood of adherence to treatment. She should also be told to contanct you
immediately if a rash, itching or rising fever occur.
Patient 38 (migraine)
In addition to other information the important instruction here is that
the drug (preferably a suppository) should be taken 20 minutes before the
analgesic, to prevent vomiting. Because of possible sedation and loss of
coordination she should be warned not to drive a car or handle dangerous
machinery.
Sample
page of a personal formulary
Tablet 20,100 mg Beta blocker ATENOLOL
*
DOSAGE
Hypertension: start with 50
mg in the morning. Average: 50-100 mg per day.
Angina pectoris: 100 mg per
day in 1-2 doses
Adjust to each patient
individually, start as low as possible. Raise the dose after 2 weeks, if
needed.
*
WHAT TO TELL THE PATIENT
Information
Hypertension: drug decreases
blood pressure, patient will usually not notice any effect. Drug will prevent
complications of high blood pressure (angina, heart attack, cerebrovascular
accident).
Angina pectoris: decreases
blood pressure, prevents the heart from working too hard, preventing chest
pain.
Side effects: hardly any,
sometimes slight sedation.
Instructions
Take the drug .. times per
day, for ... days
Warnings
Angina pectoris: do not
suddently stop taking the drug
Next appointment
Hypertension: one week.
Angina pectoris: within one
month, earlier if attacks occur more frequently, or become more severe
*
FOLLOW-UP
Hypertension: during first
few months pulse and blood pressure should be checked weekly. Try to decrease
dosage after three months. Higher dosages do not increase therapeutic effect,
but may increase side effects. Try to stop treatment from time to time.
Angina pectoris: in case
frequency or severity of the attacks increase, more diagnostic tests or other
treatment are needed. Try to stop drug treatment from time to time.
Exercise: patient 39-42
In the following cases, try
to decide whether the treatment can be stopped or not. Cases are discussed
below.
Patient 39:
Man, 40 years. Review visit after pneumonia, treated with oral
ampicillin (2 grams daily) for one week. No symptoms remain, only slight
unproductive cough. Examination normal.
Patient 40:
Man, 55 years. Severe myalgia and undefined arthritis for many years. Has been on prednisolone (50
mg daily) and indometacin (10 mg daily) for a long time. Epigastric pain and
pyrosis over several months, for which he takes aluminum hydroxide tablets from
time to time. During the consultation he complains that the epigastric pain and
pyrosis have not disappeared; in fact they have become worse.
Patient 41:
Woman, 52 years. Mild hypertension for the past two years. Responded
well to a thiazide diuretic (25 mg daily). The maintenance dose has already
been decreased twice because her blood pressure had dropped to around normal.
She regularly forgets to take the drug.
Patient 42:
Man, 75 years. Had been prescribed temazepam for one week, (10 mg
daily) because of sleeplessness after his wife died six months ago. He asks for
more, because he is afraind he will still not be able to sleep.
Patient 39 (pneumonia)
The course of treatment was defined in advance. It was effective and
without side effects. The ampicillin can be stopped.
Patient 40 (epigastric pain)
In this case the treatment has not been effective because the
epigastric pain is a side effect of the drugs used for myalgia. The treatment
that really needs monitoring is the anti-inflammatory drugs, not the aluminium
hydroxide. The problem can be solved by finding out whether the pain occurs at
certain times, rather than being continuous. In this case the dosage schedule
could be adjusted to reach peak plasma concentrations at those times, and the
total daily dose could be lowered. The lesson to be learned from this patient
is that it is better to reconsider the original therapy rather than to „treat“
its side effects with another drug.
Patient 41 (mild
hypertension)
This treatment seems effective and without side effective and without
side effects. The patient is no longer hypertensive and may not need continued
therapy, especially since she regularly forgets to take the drug. You can stop
the treatment for assessment but you must continue to monitor the patient.
Patient 42 (insomnia)
As the patient wants to continue the treatment it was obviously
effective. However, benzodiazepines can produce psychological and physical
dependence when taken regularly for more than a few weeks. In addition,
tolerance develops quickly and this can lead patient and also tell him that the
nature of the sleep induced by such drugs is not the same as normal sleep, but
the result of suppressed brain activity. Encourage him to try to return to
natural sleep patterns; possibly a warm bath or a hot milk drink will help
to promote relaxation before bedtime. It may also help to encourage him to
express his feeling about his loss; acting as a sympathetic
listener is probably your major therapeutic role in this case, rather than
prescribing more drugs. In this case the drug can be stopped at once because it
was only used for one week. This cannot be done when patients have taken
benzodiazepines for longer periods of time.
Summary
Step 6: Monitor (and stop?)
the treatment
Was the treatment effective?
a. Yes, and disease
cured: Stop the treatment
b. Yes, but not yet
completed: Any serious side
effects?
n No: treatment can be
continued
n Yes: reconsider
dosage or drug choice
c. No, disease not
curred: Verify all steps:
n Diagnosis correct?
n Therapeutic
objective correct?
n P-drug suitable for
this patient?
n Drug prescribed
correctly?
n Patient instructed
correctly?
n Effect monitored
correctly?
Posts
