Download Workshop 2: Adverse Drug Reactions

Workshop 1: Navigating the eBNF, eMC, NetDoctor
and NHS Direct Q&As
Use the eBNF, eMC and NetDoctor to answer the following questions. What do you
consider to be the advantages and disadvantages of these information sources?
1
What is the starting dose of
doxazosin for
hypertension?
eBNF: 1mg daily, increased after 1–2 weeks
to 2mg once daily, and thereafter to 4 mg once
daily, if necessary; max. 16 mg daily
eMC: Doxazosin is used in a once daily
regimen. The dose of Doxazosin should be
adjusted according to the patient's response.
The initial dose of Doxazosin should be 1 mg
per day. Dosage may then be increased in
intervals of 1 or 2 weeks to 2 mg and
thereafter to 4 mg. If necessary, dosage can
be further increased to 8 mg or the maximum
recommended dose of 16 mg.
NetDoctor: No information.
2
What active ingredient does
Flamatak MR contain and
how much?
eBNF: Diclofenac 75mg (difficult to find)
eMC: Diclofenac 75mg.
NetDoctor: Diclofenac but no strength.
3
Can I buy Almogran in the
chemist
eBNF: Prescription only medicine (POM).
eMC: Prescription only medicine (POM).
NetDoctor: Prescription only.
4
Name three side effects of
Distamine
eBNF: Lots of side effects stated within main
monograph.
eMC: Lots of side effects stated.
NetDoctor: Lots of side effects stated.
5
Can phenelzine and
pseudoephedrine be taken
together safely?
eBNF: Appendix 1 phenelzine - risk of
hypertensive crisis when MAOIs given with
phenylpropanolamine.
eMC: Sudafed SPC- Concomitant use of
SUDAFED Plus with sympathomimetic agents
such
as
decongestants,
tricyclic
antidepressants, appetite suppressants and
amphetamine-like psychostimulants or with
monoamine oxidase inhibitors, which interfere
with the catabolism of sympathomimetic
amines, may occasionally cause a rise in blood
pressure.
NetDoctor: Monograph for pseudoephedrine pseudoephedrine may interact with monoamine
oxidase inhibitor antidepressants (MAOIs, eg
phenelzine, tranylcypromine) to produce a
dangerous increase in blood pressure. For this
reason, this medicine should not be taken at
the same time as, or within 2 weeks of stopping
an MAOI.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
6
Can Ibuprofen and lithium
be taken together safetly?
eBNF:
Potentially hazardous,
ibuprofen
reduces excretion of lithium (increased risk of
toxicity)
eMC: Serum lithium concentrations may
increase during concomitant therapy with nonsteroidal
anti-inflammatory
drugs
or
tetracycline, possibly resulting in lithium toxicity.
Serum lithium concentrations therefore should
be monitored more frequently if NSAID or
tetracycline therapy is initiated or discontinued.
NetDoctor: The following medicines may
increase the levels of lithium in the blood,
causing an increased risk of lithium side effects:
non-steroidal
anti-inflammatory
drugs
(NSAIDs), such as indomethacin, diclofenac,
ibuprofen.
7
Can azithromycin be used in
a patient with liver disease?
eBNF: Contra-indications: hepatic impairment.
Appendix 2. Avoid; jaundice reported
eMC: As the liver is the principal route of
excretion of azithromycin, it should not be
used in patients with hepatic disease.
NetDoctor: Use with caution in decreased
liver function.
8
I am taking bezafibrate
400mg, one tablet every day
– does it matter what time I
take it?
eBNF: 1 tablet daily after food.
eMC: The tablets should be swallowed whole
with a little fluid after a meal a night or in the
morning.
NetDoctor: No specific information.
9
I need to take trimethoprim
for a UTI, is it safe as I’m
breast-feeding?
eBNF: Appendix 5. Present in milk—shortterm use not known to be harmful
eMC: Although trimethoprim is excreted in
breast milk, lactation is not a contra-indication
for short-term trimethoprim therapy.
NetDoctor: This medicine passes into breast
milk. Seek medical advice from your doctor
before
using
this
medicine
during
breastfeeding.
10
Is warfarin safe in
pregnancy?
eBNF: Within section before main mongraph.
Oral anticoagulants are teratogenic and should
not be given in the first trimester of pregnancy.
Women at risk of pregnancy should be warned
of this danger since stopping warfarin before
the sixth week of gestation may largely avoid
the
risk
of
fetal
abnormality.
Oral
anticoagulants cross the placenta with risk of
placental or fetal haemorrhage, especially
during the last few weeks of pregnancy and at
delivery. Therefore, if at all possible, oral
anticoagulants
should
be avoided
in
pregnancy, especially in the first and third
trimesters. Difficult decisions may have to be
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
made, particularly in women with prosthetic
heart valves or with a history of recurrent
venous thrombosis or pulmonary embolism.
Appendix 4. First, second, third trimesters:
Congenital malformations; fetal and neonatal
haemorrhage; see also section 2.8.2
eMC: No monograph.
NetDoctor: This medicine is not to be used
during pregnancy, especially during the first
and third trimesters.
11
Do Seroquel 300 tablets
have lactose in them?
eBNF: No information.
eMC: 6.1 List of excipients. Lactose.
NetDoctor: No information.
12
After opening a bottle of
Reminyl solution, how long
does it last?
eBNF: No information.
eMC: 6.3. Shelf life. After first opening: 3
months.
NetDoctor: No information.
13
Does food affect the
absorption of levofloxacin?
eBNF: No information.
eMC: 4.2 Method of administration. The
tablets may be taken during meals or between
meals.
NetDoctor: No information.
14
I’ve just started on
methotrexate tablets. Can I
still drive?
eBNF: No information. Causes drowsiness.
eMC: 4.7 Effects on ability to drive and use
machines. None known.
NetDoctor: No specific information although
states drowsiness and burred vision within
side effects.
Use the NHS Direct medicines calls Q&As to answer the following questions. Can you find
the answers in the eBNF, eMC or netdoctor?
15
When can I drink alcohol
again after taking a course
of Metronidazole?
eBNF: No information.
eMC: No information.
NetDoctor: You should not drink alcohol while
taking this antibiotic, and for at least 48 hours
after finishing the course, as this can cause
unpleasant symptoms such as hot flushes,
abdominal
cramps,
nausea,
vomiting,
headache and palpitations.
FAQs: Full referenced answer.
16
Can I take paracetamol with
amoxicillin?
eBNF: No information.
eMC: No information.
NetDoctor: No information.
FAQs: Full referenced answer.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 2: Handling Medicines Calls
Case Scenario 1
Question
What further
background
information do
you need to
clarify the
question and
minimise the risks
when advising the
caller?
A lady says she saw a specialist at the hospital because she has really bad
migraines. She has just picked up her prescription, but the leaflet in the box
says it’s for epilepsy. She asks if she has got epilepsy, or if the pharmacist
or doctor has made a mistake?
PERSON
MEDICINES
Who is asking?
42 year old female - about herself
Medicines (name,dose,freq)?
Sodium valproate 300mg twice a day
(just been prescribed).
Thyroxine 100 micrograms a day.
New or worsening symptoms?
Just seen specialist for bad
Why asking about medicines?
migraines.
Doctor said that new medicine wasn’t
Allergies/medical conditions?
widely used and explained side effects.
No allergies. Hypothyroidism.
Leaflet says medicine is for epilepsy.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
eBNF:
4.7.4.2 Prophylaxis of migraine: sodium valproate may be used for migraine
prophylaxis. 4.8.1 Sodium valproate (unlicensed) may be effective in a dose
of 300mg twice a day.
eMC:
No information.
netdoctor:
No information.
Martindale 33rd edition:
Sodium valproate has been shown to be effective and well tolerated in the
prophylaxis of migraine.
Prodigy:
Sodium valproate (unlicensed) has some evidence of efficacy at doses of
300 mg twice a day. There is more evidence of efficacy for semisodium
valproate (divalproex sodium), but this is also an unlicensed use. Weight
gain, tremor, and hair loss are potential adverse effects. Liver function
should be checked before treatment is started and during the first 6 months
of therapy. Valproates should only be taken by women of child-bearing
potential if they are using adequate contraception.
What advice
would you give?
Or would you
refer?
Sodium valproate is a medicine originally developed to treat epilepsy. Some
doctors have carried out clinical trials that show sodium valproate can help
people with migraine. However, it does not have a license for use in this
way. In the meantime, doctors are allowed to prescribe sodium valproate for
migraine if they take full responsibility for its use.
The drug company cannot put information about the use of sodium
valproate for migraine in the leaflet. The doctor is responsible for explaining
the benefits and possible side effects. If you are still unsure, suggest that
you speak to your GP.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 2: Handling Medicines Calls
Case Scenario 2
Question
What further
background
information do
you need to
clarify the
question and
minimise the risks
when advising the
caller?
A lady explains that she thinks she has got thrush. She has used
Canesten pessary before but wants to know if is okay to use if pregnant.
PERSON
MEDICINES
Who is asking?
27 years old pregnant lady.
Medicines (name,dose,freq)?
None.
New or worsening symptoms?
Why asking about medicines?
Discharge, exactly like thrush Went to pharmacist but she said that
diagnosed by GP 12 months ago.
I had to see my GP. Why can’t I buy
from the pharmacy as before?
Any allergies/medical conditions?
No allergies / medical conditions.
Pregnancy (stage, going well)?
18 weeks. First pregnancy, all well.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
medicines-chest.co.uk
Canesten pessary contains clotrimazole 500mg.
eBNF:
No information.
eMC / Canesten:
In animal studies clotrimazole has not been associated with teratogenic
effects, but following oral administration of high doses to rats there was
evidence of foetotoxicity. The relevance of this effect to topical application in
humans is not known. However, clotrimazole has been used in pregnant
patients for over a decade without attributable adverse effects. It is therefore
recommended that clotrimazole should be used in pregnancy only when
considered necessary by the doctor. As a measure of precaution
Clotrimazole Vaginal Tablets should not be used in early pregnancy. During
pregnancy, treatment with should be carried out only after consulting the
attending doctor and without using an applicator.
netdoctor:
There is no information about the safety of clotrimazole during pregnancy. It
has been used in pregnancy for over a decade without adverse effects,
however you should consult your doctor before using this medicine. Avoid
using the applicator to insert the medicine during pregnancy.
Toxbase:
First-line treatment of candida infection in pregnancy is with a topical
imidazole, such as clotrimazole. Clotrimazole is used topically and
intravaginally, with only 3-10 % of the dose being systemically absorbed. It
has been widely used to treat candida infections occurring during
pregnancy, with no evidence of an increased risk of foetal malformations or
spontaneous abortions above the background rate.
What advice
would you give?
Or would you
refer?
Topical treatment with Canesten is the treatment of choice for vaginal
thrush in pregnancy. However, pregnant women should not self-treat. A
doctor should first screen for susceptibility to thrush e.g. diabetes. Pharmacy
packs are not licensed for use by pregnant women without first consulting a
doctor. If Canesten pessary, avoid using the applicator.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 2: Handling Medicines Calls
Case Scenario 3
Question
What further
background
information do
you need to
clarify the
question and
minimise the risks
when advising the
caller?
A lady asks if it is safe for her to take Benadryl whilst breastfeeding.
PERSON
MEDICINES
Who is asking?
32 years old lady.
Exact type of Benadryl
Benadryl One-a-Day.
New or worsening symptoms?
Other meds (name,dose,freq)?
Hayfever. Occurs every year, None.
usually controlled with cetirizine.
Has medicine been taken?
Any allergies/medical conditions? Yes, one this morning.
No allergies / medical conditions.
Why asking about medicines?
Baby?
Tried to speak to health visitor / GP
12 weeks. Born at term. Healthy. but not available until after the weekFeeding about every 2-3 hours.
end.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
medicine-chest.co.uk:
Benadryl One-a-Day contains cetirizine 10mg.
eBNF:
Benadryl One-a-Day not listed.
Cetirizine: Significant amount of some antihistamines present in milk; although
not known to be harmful manufacturers of alimemazine, cetirizine,
cyproheptadine, desloratadine, fexofenadine, hydroxyzine, loratadine,
mizolastine and terfenadine advise avoid; adverse effects in infant reported with
clemastine.
eMC / cetirizine:
Cetirizine is contraindicated in lactating women as excreted in breast milk.
netdoctor:
This medicine may pass into breast milk. It should not be used by
breastfeeding mothers.
UKMI Central:
 Individual maternal and infant situations must be taken into account
before any drug is prescribed for the mother.
 In general, all drugs should be avoided in premature or low birth weight
infants, or in those who have any underlying conditions.
 Drug should be used at the lowest dose and for the shortest time.
 Preferred drug is non-sedating, has a favourable ADR profile, a relatively
short half-life and has data to support safe use in breast feeding.
Sedating drug
Chlorpheniramine
No Risk of drowsiness and poor feeding
Clemastine
No As above. Single report of infant drowsiness and
irritability when added to anticonvulsant regimen
Diphenydramine
No Risk of drowsiness and poor feeding
Promethazine
No As above
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Non-sedating drug
Acrivastine
What advice
would you give?
Or would you
refer?
?
No data available
Astemizole
No Long half-life, risk of accumulation esp in neonates.
Cetirizine
Yes Low levels in milk
Fexofenadine
Loratadine
? No clinical data available
Yes Low levels in milk
Refer to MI Service as conflicting information.
MI Service answer:
Breastfeeding mothers with hayfever can be treated with a number of
medicines to control symptoms without concern of untoward effects on the
nursing infant. However, the decision to treat should always be based on a
risk versus benefit evaluation in each individual case.
In general, medicines should be avoided by mothers breast feeding
premature or low birth weight infants, or in infants who have any underlying
medical conditions.
 Avoid precipitating allergens, if known.
 Assess risk and benefits.
 If a medication is prescribed, it should be at the lowest practical dose and
for the shortest period of time.
 Initially use topical treatment: intranasal corticosteroids and/or sodium
cromoglicate eye drops.
 Cetirizine or loratadine are the antihistamines recommended for a
breastfeeding mother.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 3: Adverse Drug Reactions
Case Scenario 1
Question
What further
background
information do
you need to
clarify the
question and
minimise the
risks when
advising the
caller?
I have just been prescribed Roaccutane and have been told that I shouldn’t
wax my legs. Will this be forever or is it only for the duration of time that I
am on it?
PERSON
MEDICINES
Who is asking?
19 year old female – about herself
Medicines (name,dose,freq)?
Roaccutane 30mg once a day.
Microgynon 30 .
New or worsening symptoms?
No symptoms.
Any allergies/medical conditions?
No allergies. Acne since mid teens.
Why asking about medicines?
Would like further explanation of
what the specialist said.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
eBNF:
Roaccutane contains isotretinoin.
Side-effects of isotretinoin include severe dryness of the skin and mucous
membranes, nose bleeds, and joint pains. The drug is teratogenic and must
not be given to women of child-bearing age unless they practise effective
contraception and then only after detailed assessment and explanation by
the physician. WAX EPILATION AND DERMABRASION. Warn patient to
avoid wax epilation during treatment and for at least 6 months after stopping
(risk of epidermal stripping); avoid dermabrasion during treatment and for at
least 6 months after stopping (risk of scarring)
eMC – PIL/Roaccutane:
You will probably have some unwanted reactions to your treatment, even
before you see your acne getting better. These effects often wear off as your
treatment continues and your doctor can help you to deal with them. You
should expect dryness of the skin, especially of the lips and face and you
may get inflamed or chapped lips, a rash, some mild itching and slight
peeling. Dryness of the throat may cause hoarseness. Your skin may
become more fragile and redder than usual. This dryness can be relieved by
the regular use of a good moisturising cream from the start of treatment.
Petroleum jelly is particularly good. The inside of the nose may become dry
and "crusted" causing mild nosebleeds. Smearing a thin layer of petroleum
jelly on the inside of the nose will help.
netdoctor:
Avoid waxing any part of the body during therapy with isotretinoin, and for up
to six months after stopping therapy, due to risk of inflammation of the skin
(dermatitis) and scarring.
What advice
would you give?
Or would you
refer?
Well-known side effect of Roaccutane related to the high dose of vitamin A.
Avoid waxing any part of the body during therapy with isotretinoin, and for up
to six months after stopping therapy, due to risk of inflammation of the skin
(dermatitis) and scarring.
Further learning points
Isotretinoin, a Vitamin A analogue, is very toxic and may only be prescribed by / under
supervision of a consultant dermatologist. It is teratogenic. Women of childbearing age must be
fully informed and practice effective contraception.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 3: Adverse Drug Reactions
Case Scenario 2
Question
What further
background
information do
you need to
clarify the
question and
minimise the
risks when
advising the
caller?
My son has a rash all over his body and is feeling unwell. He has recently
started lamotrigine, could this be causing the rash?
PERSON
MEDICINES
Who is asking?
Mother about 8 years old son.
Medicines (name,dose,freq)?
Lamotrigine 5mg each day.
Sodium Valproate 200mg twice a
New or worsening symptoms?
day.
Rash – raised red bumps., not How long been on these, who
bleeding, all over him. Started prescribed them?
yesterday evening. He is hot and Lamotrigine started about 3 weeks
feels unwell.
ago by specialist as sodium valporate
not controlling the fits.
Any allergies/medical conditions?
Epilepsy.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
eBNF:
SKIN REACTIONS. Serious skin reactions including Stevens-Johnson
syndrome and toxic epidermal necrolysis (rarely with fatalities) have
developed especially in children; most rashes occur in the first 8 weeks. The
CSM has advised that factors associated with increased risk of serious skin
reactions include concomitant use of valproate, initial lamotrigine dosing
higher than recommended, and more rapid dose escalation than
recommended. COUNSELLING. Warn patients to see their doctor
immediately if rash or influenza-like symptoms associated with
hypersensitivity develop
eMC / Lamictal:
In double-blind, add-on clinical trials, skin rashes occurred in up to 10% of
patients taking lamotrigine and in 5% of patients taking placebo. The skin
rashes led to the withdrawal of lamotrigine treatment in 2% of patients. The
rash, usually maculopapular in appearance, generally appears within eight
weeks of starting treatment and resolves on withdrawal of lamotrigine
Rarely, serious potentially life threatening skin rashes, including Stevens
Johnson syndrome and toxic epidermal necrolysis (Lyell Syndrome) have
been reported. Although the majority recover on drug withdrawal, some
patients experience irreversible scarring and there have been rare cases of
associated death. The approximate incidence of serious skin rashes
reported as SJS in adults and children over the age of 12 is 1 in 1000. The
risk in children under the age of 12 is higher than in adults. Available data
from a number of studies suggest that the incidence in children under the
age of 12 requiring hospitalisation due to rash ranges from 1 in 300 to 1 in
100.
In children, the initial presentation of a rash can be mistaken for an infection;
physicians should consider the possibility of a drug reaction in children that
develop symptoms of rash and fever during the first eight weeks of therapy.
Additionally the overall risk of rash appears to be strongly associated with:High initial doses of lamotrigine and exceeding the recommended dose
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
escalation of lamotrigine therapy, Concomittant sodium valproate.
Rash has also been reported as part of a hypersensitivity syndrome
associated with a variable pattern of systemic symptoms including fever,
lymphadenopathy, facial oedema and abnormalities of the blood and liver.
The syndrome shows a wide spectrum of clinical severity and may, rarely,
lead to disseminated intravascular coagulation (DIC) and multiorgan failure.
It is important to note that early manifestations of hypersensitivity (e.g.,
fever, lymphadenopathy) may be present even though rash is not evident.
Patients should be warned to seek immediate medical advice if signs and
symptoms develop. If such signs and symptoms are present the patient
should be evaluated immediately and Lamictal discontinued if an alternative
aetiology cannot be established.
netdoctor:
Adverse skin reactions have been reported with lamotrigine. These reactions
are usually mild and self-limiting, but can on rare occasions be more serious
and potentially life-threatening. When starting treatment with lamotrigine the
dose is increased gradually to minimise the risk of developing such a rash.
For this reason it is very important to follow the instructions you are given
with this medicine, and not to exceed the prescribed dose. If you develop a
rash, fever, facial swelling or swollen glands while taking this medicine you
should consult your doctor immediately.
What advice
would you give?
Or would you
refer?
Rash is a common side effect of lamotrigine. It is usually red and raised and
often begins within the first 8 weeks of treatment. However, it can be a more
serious side effect especially if there is also fever.
Advise that the son sees the GP immediately or is taken to A&E. Please
explain that you have phoned NHS Direct and this is what was advised. It is
important that the rash be seen by a doctor and if due to lamotrigine then
treated quickly.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 3: Adverse Drug Reactions
Using the MHRA Website
1. What hot topics are in the news?
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 4: Drug Interactions
Case Scenario 1
Question
What further
background
information do
you need to
clarify the
question and
minimise the risks
when advising the
caller?
Is it okay to take amoxicillin whilst taking the pill?
PERSON
MEDICINES
Who is asking?
28 year old female - about herself
Medicines (name,dose,freq)?
Amoxicillin 500mg three times a day.
Cilest. How many pills left? 12
New or worsening symptoms?
Have you taken the antibiotic? No
GP diagnosed a chest infection this Salbutamol inhaler 2 puffs when
morning.
needed.
Becotide 100 inhaler 2 puffs twice a
Any allergies/medical conditions? day.
No allergies. Asthma.
Why asking about medicines?
Forgot to check that doctor aware I
was taking the pill.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
eBNF:
Some broad-spectrum antibiotics (e.g.ampicillin, doxycycline) may reduce
the efficacy of combined oral contraceptives by impairing the bacterial flora
responsible for recycling of ethinylestradiol from the large bowel. FPA
advice is that additional contraceptive precautions should be taken whilst
taking a short course of a broad-spectrum antibiotic and for 7 days after
stopping. If these 7 days run beyond the end of a packet the next packet
should be started immediately without a break (in the case of ED tablets the
inactive ones should be omitted). If the antibiotic course exceeds 3 weeks,
the bacterial flora develops antibiotic resistance and additional precautions
become unnecessary; additional precautions are also unnecessary if a
woman starting a combined oral contraceptive has been on a course of
antibiotics for 3 weeks or more.
eMC / Cilest:
Irregular cycles and reduced reliability of oral contraceptives may occur
when these preparations are used concomitantly with drugs such as
anticonvulsants, barbiturates, antibiotics, (eg tetracyclines, ampicillin,
rifampicin, etc), griseofulvin, activated charcoal and certain laxatives.
netdoctor / Cilest:
The contraceptive effect of this medicine may be reduced when taken with:
 Rifamycins such as rifabutin and Rifampicin
 Antiepileptic medicines such as carbamazepine, phenytoin, phenobarbital
and primidone
 Antibiotic medicines such as penicillins
 Antifungal medicines such as fluconazole, itraconazole, ketoconazole and
griseofulvin.
Tell your doctor if you are taking any of these medicines before starting the
pill. Barrier contraceptives such as condoms should be used whilst taking a
short course of antibiotics or antifungals, and for 7 days after the course has
finished.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Stockley 6th edition:
The oral contraceptive / penicillin interaction is inadequately established and
controversial. The total number of failures is extremely small. However, the
personal and ethical consequences of an unwanted pregnancy can be very
serious. For this reason the general advice is that a second (barrier) method
of contraception be used whilst taking the penicillin and for 7 days after
finishing the course. The FPA recommend that if the 7 days run beyond the
end of the packet then the new packet should be started without a pill-free
break.
What advice
would you give?
Or would you
refer?
There is a risk that amoxicillin may stop the pill from working properly.
Advise to use a barrier method during the time that she is on the antibiotic
and for 7 days following the end of the course (i.e. 14 days).
As there are only 12 tablets left in the pack, start the next pack of pills
straight away without the 7-day pill free period. Explain that this is safe and
that she will not get the usual withdrawal bleed.
Further learning points
For questions about the contraceptive pill
 Ask how many pills are left in the pack
 Ask if the second medicine has already been taken. May need to assess the risk of
contraceptive failure.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006
Workshop 4: Drug Interactions
Case Scenario 2
Question
What further
background
information do
you need to
clarify the
question and
minimise the risks
when advising the
caller?
I have just been to see my doctor. He has given me some ciprofloxacin. I
am taking warfarin. Is it ok to take them together?
PERSON
MEDICINES
Who is asking?
61-year old female - about herself.
Medicines (name,dose,freq)?
Warfarin 3mg once a day.
Ciprofloxacin 500mg twice a day for
1 week.
New or worsening symptoms?
Doctor has diagnosed a urinary tract
Why asking about medicines?
infection.
Yellow dosing book warns about
Any
allergies
or
medical taking other medicines with warfarin.
conditions?
No allergies. DVT 3 months ago.
Gather the further background information BEFORE searching for information.
What information
sources would
you use?
eBNF:
Ciprofloxacin and coumarins
anticoagulant effect.
–
potentially
hazardous.
Enhanced
eMC / Ciproxin:
Prolongation of bleeding time has been reported with concomittent
administration of ciprofloxacin and oral anticoagulants.
netdoctor
Ciprofloxacin may prolong the bleeding time. Recommends that INR is
monitored and speak to doctor if signs of bleeding.
Stockley 6th edition:
Increases the prothrombin time and risk of bleeding.
What advice
would you give?
Ciprofloxacin can in some people enhance the effects of warfarin. This
means it can make your blood too thin and increase the risk of bleeding.
Or would you
refer?
Suggest you phone your GP. He may want to change your antibiotic or
monitor your blood more closely.
Signs that your blood is too thin include nosebleeds, easily bruising and
blood in the urine. If these occur, speak to your GP immediately.
Further learning points
Warfarin is a narrow therapeutic range drug
 small increases in blood level can lead to haemorrhage including stroke
 small decreases in blood level can result in blood clots (stroke, DVT, PE)
Ciprofloxacin inhibits the metabolism of many medicines.
Role Preparation for NHS Direct NAs: Handling Medicines Calls
August 2006