MR pharm Flashcards
A 66 year old patient sees you in clinic. She is planning to undergo a prolapse repair. Her BP in clinic is 132/84. You note on her pre-op bloods that her Sodium is 129 mmol/l. Otherwise her U&Es and FBC are within normal parameters. Her medication list is below:
Aspirin 75mg OD
Atenolol 50mg OD
Furosemide 40mg OD
Ramipril 5mg OD
Simvastatin 10mg OD
Which of her medications is most likely to cause hyponatraemia:
Cardiac Medications
Below are some common and important side effects encountered with commonly used medications. The lists are not exhaustive but should highlight side effects that you may be asked about in the exam.
ACE inhibitors eg Ramipril
Dry Cough (10%)
Joint aches
Postural hypotension (infrequent)
Renal Impairment (rare)
Angio-odema (rare)
NOTE: Avoid in Pregnancy as skull defects, oligohydramnios and altered neonatal BP and renal blood flow reported.
Loop Diuretics eg Furosemide
Postural Hypotension
Hyponatraemia
Hypokalaemia
Hypocalcaemia and Hypomagnesaemia
Gastrointestinal upset
Calcium Channel Blockers eg Amlodipine
Peripheral oedema Abdominal pain Nausea Fatigue
NOTE The BNF advises most calcium channel blockers be avoided in pregnancy as they may inhibit labour and some have shown toxicity in animal studies
Beta Blockers eg labetalol
Bronchospasm Cold extremities Alteration in glycaemic control Bradycardia
NOTE Labetalol has not been shown to be harmful except possibly in the 1st trimester. Other beta blockers may cause IUGR
An 26 year old patient currently 9 weeks pregnant. This is her 1st pregnancy. She has been suffering with nausea and vomitting that has failed to respond to conservative measures including ginger, dietary changes and acupuncture. She wants to start medical therapy. Which of the following is 1st line drug treatment according to NICE guidance?
- Domperidone
- Ondans
- Promethazine
- Haloperidol
- Metoclopramide
Ans Promethazine
Antiemetics
- Cyclizine Histamine H1-receptor antagonist
- Promethazine Histamine H1-receptor antagonist
- Ondansetron Serotonin 5-HT3 receptor antagonist
- Prochlorperazine Dopamine D2 receptor antagonist
- Metoclopramide Dopamine D2 receptor antagonist
5-HT3 receptor antagonist
5-HT4 receptor agonist
Which of the following best describes the mechanism of action of Cyclizine?
Cyclizine is type of antihistamine that acts on the H1 receptor.
In pregnancy NICE guidelines advise oral promethazine or oral cyclizine should be used as 1st line drug management of nausea and vomitting. Both are H1 antagonists.
Which of the following is an appropriate treatment for Diazepam overdose?
Flumazenil
Flumazenil is used for benzodiazepine overdose.
Naloxone is used for opioid overdose.
Parvolex (N-acetyl cysteine) is used for paracetamol overdose.
Protamine can be used for Heparin reversal.
Beriplex can be used for Warfarin reversal.
You are asked to prescribe VTE prophylaxis for a 26 year old patient who is 37 weeks pregnant. She is 72Kg. What dose of Dalteparin would you use?
5000 U
Weight (kg) Enoxaparin Dalteparin Tinzaparin
<50 20mg 2500u 3500u
50 to 90 40mg 5000u 4500u
91-130 60mg 7500u 7000u
131-170 80mg 10,000u 9000u
>170 0.6mg/kg 75u/kg 75u/kg
Which of the following drugs is a Dihydrofolate reductase (DHFR) inhibitor?
Methotrexate
Tetrahydrofolate and its derivatives are essential for purine and thymidylate synthesis, which are important for cell proliferation and cell growth. Dihydrofolate reductase (DHFR) enzyme catalyses the conversion of dihydrofolate to tetrahydrofolate.
In humans deficiency of DHFR can lead to folate deficiency and megaloblastic anaemia.
The 2 most commonly used DHFR inhibitors are:
Trimethoprim Methotrexate.
Some antimalarials are also DHFR inhibitors.
A patient is on the ward with a mechanical mitral valve. There is no history of VTE. What is the target INR?
2.5-3.5
With regard to warfarin therapy there are only 3 target ranges that are commonly used:
2. 0 - 3.0 Most common used for DVT,PE & tissue valve replacement treatment 2. 5 - 3.5 Used in mechanical mitral valve replacement & some aortic mech.valve replacements 3. 0 - 4.0 Used in mechanical valve replacement where PE has occurred despite anticoagulation at lower range
Warfarin
RCOG updated its Greentop guidelines on thromboprophylaxis in 2015.
Warfarin has a very limited role in pregnancy and as such there is limited scope for questioning but you should be familiar with the following
Key Points
People on warfarin should be converted to LMWH during pregnancy Very few exceptions to above. Mechanical heart valves main one Warfarin causes a characteristic warfarin embryopathy in 5% of foetuses exposed to warfarin between 6 and 12 weeks gestation Warfarin is safe to use when breastfeeding Women converted to LMWH from warfarin during pregnancy should be changed back 5-7 days after delivery Also remember you may also be asked how warfarin works! It inhibits vitamin K dependent clotting factors (10,9,7,2)
Warfarin Embryopathy
Hypoplasia of nasal bridge
Congenital heart defects
Ventriculomegaly
Agenesis of the corpus callosum
Stippled epiphyses
A 27 year old patient is maintained on warfarin during pregnancy due to a mechanical mitral valve. She has read about warfarin embryopathy. Which of the following is a typical feature?
Stippled epiphyses are multiple ossification centers that severely deform the long bone and give it a stippled appearance and a thickened shaft. It is a feature of Warfarin Emryopathy (AKA Fetal Warfarin Syndrome). Other features include:
Hypoplasia of nasal bridge
Laryngomalacia
Pectus carinatum
Ventriculomegaly
Agenesis of the corpus callosum
Telebrachydactyly
Growth retardation
With regard to opioid receptors. Morphine acts primarily as a potent?
Opoids
Opioids may act at Mu, Kappa or Delta receptors.
Strong opioids commonly used in clinical practice i.e.
Morphine Fentanyl Methadone
are strong agonists of the Mu receptor.
Weak opioids such as codeine and tramadol are also agonists of the Mu receptor but also act as agonists at the Delta and Kappa receptors
Which of the following best describes the mechanism of action of Promethazine?
Promethazine is type of antihistamine that acts on the H1 receptor.
In pregnancy NICE guidelines advise oral promethazine or oral cyclizine should be used as 1st line drug management of nausea and vomitting. Both are H1 antagonists.
How does Ranitidine work?
GORD
Reflux Medication
The Proton Pump of gastric parietal cells has 3 main receptors (histamine, gastrin and acetylcholine) that if agonised will stimulate proton (H+ or ‘acid’) release. H2 is the most significant receptor and stimulation of this pathway is thought to account for around 85% of proton pump stimulation. Ranitidine and other H2 antagonists block this receptor reducing proton pump stimulation
PPIs work by blocking the whole proton pump from working.
A fetus is noted to be small for gestational age (SGA) on the 20 week scan. One of the mothers medications is stopped at this time. Follow up scans reveal renal dysgenesis. Which of the below medications was stopped?
This is IUGR and renal dysgenesis. They are side effects of ACE inhibitor and ARB (angiotensin II receptor blocker) use in pregnancy.
What is the maximum dose of lidocaine (infiltrated as local anaesthetic) that should be used on a 70kg woman who is 12 weeks pregnant?
1% lidocaine =1g/100mL or 10mg/mL
Max dose for a 70kg patient is 210mg (3mg/kg)
21mL 1% plain lignocaine
Lidocaine
Lidocaine Key Points
Blocks fast voltage gated sodium channels Anti-arrhythmic Half life 2 hours Safe to use in pregnancy Hepatic metabolism Max dose is 3mg/kg (7mg/kg with adrenaline)
A women is to undergo elective C-section. According to RCOG guidance antenatal steroids should be offered to which group undergoing elective C-section?
Antenatal Corticosteroids Key Points
Why use antenatal steroids?
Antenatal steroids are associated with a significant reduction in rates of neonatal death, RDS and intraventricular haemorrhage and are safe for the mother
What does ‘a course’ mean?
Betamethasone 12 mg IM x 2 doses or dexamethasone 6 mg IM x 4 doses are the steroids of choice to enhance lung maturation
Who should be offered antenatal corticosteroids?
All women at risk of iatrogenic or spontaneous preterm birth up to 34+6 weeks gestation. All women for whom an elective c-section is planned prior to 38+6 weeks gestation
When should antenatal steroids be given?
A single course should be offered to women between 24+0 and 34+6 weeks gestation who are at risk of preterm birth
When are antenatal steroids most effective?
Risk of neonatal death reduces if steroid given within first 24 hours and therefore should still be given even if delivery is expected within this time Most effective in reducing RDS in pregnancies that deliver 24 hours after and up to 7 days after administration of the second dose of antenatal corticosteroids
Warfarin embryopathy is typically the result of the mother taking warfarin during which stage of pregnancy?
6-12 weeks
Warfarin
RCOG updated its Greentop guidelines on thromboprophylaxis in 2015.
Warfarin has a very limited role in pregnancy and as such there is limited scope for questioning but you should be familiar with the following
Key Points
People on warfarin should be converted to LMWH during pregnancy Very few exceptions to above. Mechanical heart valves main one Warfarin causes a characteristic warfarin embryopathy in 5% of foetuses exposed to warfarin between 6 and 12 weeks gestation Warfarin is safe to use when breastfeeding Women converted to LMWH from warfarin during pregnancy should be changed back 5-7 days after delivery Also remember you may also be asked how warfarin works! It inhibits vitamin K dependent clotting factors (10,9,7,2)
Warfarin Embryopathy
Hypoplasia of nasal bridge
Congenital heart defects
Ventriculomegaly
Agenesis of the corpus callosum
Stippled epiphyses
