Pharmacology Flashcards
IV treatment for torsade de pointes
Magensium
What drug can be used in addition to adrenaline in patients with anaphylaxis and taking Beta-blockers?
Glucagon
What states predispose to digoxin toxicity?
Hypoxia, hypercalaemia, hypokalaemia, hypomagnesaemia
Contraindications for nitrous oxide
In patients with air containing closed spaces e.g. pneumothorax
Raised ICP
Mechanism for ACEi caused cough
Decreased bradykinin breakdown
Nitromidazole class MOA
Bacterial nucleic acid synthesis inhibitor
Quinolones MOA
Bacterial nucleic acid synthesis inhibitor
How long does a lidocaine adrenaline block last?
90 mins
Digoxin contraindications
VT
Hypertrophic cardiomyopathy
Intermittent complete heart block
WPW
What increases theophylliine serum concentration?
and decreases…?
HF
Hepatic impairment
Viral infections
Fever
Elderly
Smoking and alcohol
When should the BCG vaccine be given in infancy?
40/100,000 incidence in the area
Or parents / grandparents born in a high incidence country
Digoxin MO and actions
Cardiac glycoside
Increases the force of myocardial contraction and slows the HR
Flecanide MOA
Blocks Na 2+ fast channels on cardiac tissues (inhibit influx of extracellular Na2+, decreases rate of the actiona potential
Contraindication for colchicin
Blood disorders
Short term management of HTN due to pheochromocytoma
Alpha blocker
Max dose of atropine in bradyarrhthmias with adverse features
3mg
(500 mcg IV every 3-5 mins up to a max doses of 3mg)
Define barbituate?
any of a class of sedative and sleep-inducing drugs derived from barbituric acid.
Preferred drug for RSI
Thiopental
Cautions / contraindications
Barbituates can induce hepatic enzymes, producing porphyrins
Can induce acute prophyria
Therefore contraindicated with those know to have genetic defect leading to the above
Side effects of thiopental
Extravasation -> tissue damage
Involuntary muscle movements on induction
Cough and laryngospasm
Arrythmias
Hypotension
Headache
Etomidate is…
Anaesthetic agent used for induction
(NOT used for maintence(
Etomidate suppresses…
Adrenocorticol functin
Which induction agent causes the least CV depression
Etomidate
Why has etomidate become less popular
Single induction dose blocks the normal stress-induced increase in adrenal cortisol production for up to 24hrs
Cautions for etomidate
Adrenal insufficiency e.g. sepsis
Disadvantage of propofol
Can produce hypotension and respiratory depression
Propofol uses
Induction or maintenance of anaesthesia in adults & children
Why is propofol useful in conjunction with LMA
Reduces airway and pharyngeal reflexes
How to reduce the dose of propofol needed for induction
Pre-med with opioid or benzodiazepine
Cautions for propofol
Already hypotensive patients
SE of propofol
Hypotension
Brady/tachycardia
Arrhythmias
Rash
N&V
Excitation phenomena
Headache
Transient apnoea
Propofol infusion syndrome (more than 4mg /kg/hr - potentially fatal)
Main action of ketamine
NMDA receptor antagonist
What can reduce delerium in patients given ketamine?
Pre-med with opioid or benzo
Impact of ketamine on the CV system
Sympathetic effect
Increased HR, BP and CO
Why does ketamine have a role in asthma?
Bronchial smooth muscle relaxant
Contraindictions to ketamine
Acute prophyrias
Head trauma
Stroke
Raised ICP
HTN
Severe cardiac disease
SE of ketamine
Extraneous muscle movements
Post operative N&V
HTN
Tachycardia
Transient psychotic effects
Contraindictions for NO2
Pneumothorax
Intra-cranial air
Recent underwater dive
Recent intraocular gas injection
Intestinal obstruction
Those with / at risk of ICP
Potential SE of NO2
Megalobalstic anaemia
Neurological toxic effects
Depression of white cell formation
MOA of benzodiazepines
GABA receptor agonists (enhance INHIBITORY synaptic transmission through the CNS)
Uses for benzos
Sedative
Hypnotic
Anxiolytic
Anticonvulsant
Muscle relaxant
Benzodiazepines contraindications
Cautions
Respiratory depression
Significant neuromuscular resp weakness
OSA
Severe hepatic impairement (elimination half life prolonged)
Phobic or obsessional states, chronic psychosis or hyperkinesis
Respiratory disease
Muscle weakness
Organic brain disease
Severe renal impairment (increased cerebral sensitivity)
Dependent personalitys
Frail / elderly
Hx of drug abuse
On other CNS depressants
Benzodiazepines side effects
Drowsy
Confusion
Ataxia
Muscle weakness
Headache
Withdrawl sx
Tolerance / dependence
Benzodiazepines toxicity sx
Drowsy
Atxia
Dysarthria
Nystagmus
Rarer - resp depression and coma
Antidose for benzodiazepine toxicity
Flumazenil
Duration of action
Midazolam
Lorazepam
Temazepam
Diazepam
Chlordiazepoxide
< 6hrs
12-18 hrs
24-48hrs
What type of neuromuscular block is atracurium?
Non-depolarising
MOA of atracurium
Competes with ACh, binds with receptorrs on postsynapttic membrane
Prevents depolarising and muscle contraction
What effect DOESN’T atracurium have AND why?
No sedative or analgesic effect
Nil impact on CNS
Can’t cross the BBB (water soluble)
CV SE of atracurium AND why?
How to minimise
Flushing, tachycardia, hypotension and bronchospasm
Due to histamine release
Give slowly or in divided doses
Cautions for atracurium
Myasthenia gravis / syndromes (sensitive to this drug)
Reversal agent for atracurium (non depolarising agents)
Neostigmine (anticholiesterase)
What type of neuromuscular blockade is suxamethonium?
Depolarising agent
MOA of depolarising agents
Produce PERSISTENT depolarisation at the NMJ, bind to ACh receptors but not broken down by acetlycholinesterase
Therefore AP can’t be propigated
Reversal of suxamethonium
Action can’t be reversed by drugs (neostigmine potentiates(
Recovery is spontaneous (hydrolysed rapidly in 5-10 mins by plasma pseudocholinesterase)
Premedication for suxamethonium
Glycopyrronium bromide / atropine sulfate reduces the muscarinic effects
Fatal complication of suxamethonium
Malignant hyperthermia
Malignant hyperthermia characterisation
Tachycardia, muscle spasms and rapid profound hyperthermia
MOA of local anaesthetics
Block voltage gated Na+ channeels, preventing generation of action potentials
Duration of lidocaine block
90 mins
What is prilocaine usually used for?
IV regional anaesthesia
Duration of bupivacaine block
How long does it take to take full effect
8hrs
Can take 30 mins to take full effect
Impact of LA on blood vessels
Dilation
Why does adrenaline prolong the anaesthetic effect
Vasoconstricts, diminishing local blood flow, slowing the rate of absorption
CNS toxicity sx with LA
Sedation
Anxiety
Tremor
Visual disturbance
Convlusions
Coma
Resp depression
CV toxicity sx with LA
Vasodilation
Myocardial depression with bradycardia
Examples of live attenuated vaccines (6)
BCG,
MMR
varicella-zoster
rotavirus
influenza (nasal)
polio (oral)
Examples of inactivated preparation vaccines (4)
Hep A
Influenza (IM)
Polio
Pertussis
Rabies
Examples of detoxified exotoxin vaccines (2)
Tetanus
Diptheria
Examples of extract vaccines (4)
Men A & C
Pneumococcus
Hib
Hep B
How can passive immunity be obtained medically?
Injection of immunoglobulins from the plasma of immune individuals
Two types of immunoglobulins
Normal (nonspecific) - from unselected donors. Hyperimmune (specific) - from selected donors.
Examples of disease tx with normal immunoglobulins
Hep A
Measles
Rubella
Examples of disease tx with specific immunoglobulins
Hep B
Rabes
Tetanus
Varicella-zoster r
When is immunoglobulins indicated for Hep A (2)
Prevention of ix in close contacts of confirmed cases who have / are….
Chronic liver disease
HIV ix
Immunocompromised
50yrs +
OR
Prophylaxis for immunocompromised travelling to high risk areas (where antibody response may be inadequate)
When is immunoglobulins indicated for measles?
Prevention or attenuation of an attack of measles in those without adequate immunity e.g. Infants < 9 months, non immune pregnant women who have been in contact with a confirmed case / local outbreak
Contraindications for normal immunoglobulin therapy?
Selective Ig A deficiency who have known antibody against Ig A
Indications for Hep B immunoglobulin tx
Prevention of ix in a lab setting
Accidental inoculated people
Infants born to infected mothers / high risk carriers
Agammaglobulinaemia =
lack of gamma globulin in the blood plasma, causing immune deficiency.
Hypogammaglobulinemia =
A disorder caused by low serum immunoglobulin or antibody levels.
Normal immunoglobulin and vaccine timings
SHOULD NOT BE GIVEN AT THE SAME TIME
Tx of established cases of tetanus?
Metronidazole, wound cleansing and immunoglobulin
Who is at risk of severe chicken pox?
Neonates
Children <1 yr
Pregnant females
Immunosuppressed individuals
What is in the BCG vaccine?
Live attenuated strain of M.bovis
Areas with what incidence of TB should have all neonates & infants vaccinated?
40 in 100,000
Which children should be given the BCG vaccine regardless of the area they live in?
Who have parents or grandparents born in a country where the annual incidence is 40 per 100,000
or if they lived in a country for 3 months or more where the annual incidence is 40 per 100,000
What must be confirmed before the BCG vaccine is given?
SCID screening
At how many days old should eligible babies be given the BCG vaccine?
28
The HiB vaccine can only be given ….
with other vaccines
What type of vaccine is the HiB vaccine?
Inactivated polysaccharide extracts from cultures
What is the first 3 doses of the HiB vaccine as part of?
Diptheria with tetanus, pertussis, polio & HiB
What is the booster dose of HiB given with?
Men C
What type of vaccine is the Hep A vacc?
Inactive monovalent
What type is the MMR vaccine?
Live
How many MMR vaccines should be given prior to a child entering school?
2
Which type of insulin is used in DKA?
Soluble insulin
What makes hydrocortisone unsuitable for disease suppression on a long term basis?
High mineralcorticoid activity
What type of hormonal activity does prednisolone have?
Predominantly glucocorticoid
What receptors do antihistamines act on?
H1
Antihistamine antiemetics
Cyclizine
Promethazine
MOA of phenothiazines
Dopamine antagonists, act centrally by blocking the chemoreceptor trigger zone
Examples of phenothiazine antiemetics
Chlorpromazine and prochloperazine
MOA of opioid medication
Prolonged activation of opioid receptors that are distributed with in the CNS
IV lorazepam dose in status
1 month - 11 years old
12yrs +
100 micrograms / kg (max 4mg)
4mg
Which seizure types may phenytoin exacerbate?
Absence or myoclonic
MOA of carbamazepine, lamotrigine, valproate and phenytoin
Block neuronal Na2+ channels, stabilising them in an inactive state
Cardiac condition where carbamazepine is contraindicated?
AV block
Which enzymes do NSAIDs inhibit?
COX
In patients with what co-morbidities might colchicine be useful?
HF
Anticoagulants
Main actions of digoxin
Positive inotrope and negative chronotrope
Digoxin should be used in patients with…
Persistent AF
Sedentary
Digoxin contraindicated…
In any patient with another arrhythmia (e.g. SVT, VF, HB) or hypertrophic cardiomyopathy
Cardiac SE of digoxin
SA / AV node block
PVCs
PR prolongation
ST depression
Visual SE of digoxin
Blurred or yellow vision
Tx of life threatening digoxin toxicity?
Digoxin-specific antibody
What do loop diuretics act on?
Inhibit the Na+ / K+ / 2Cl- symporter in thick ascending limb, blocks their reabsorption
Where do thiazide diuretics act?
Apical Na+ / Cl- cotransporter in early distal tubule.
Example of an osmotic diuretic
Mannitol
Osmotic diuretic MOA
Increase osmolarity of blood and renal filtrate, so less water is reabsorbed
What receptors do K+ sparing diuretics block?
Aldosterone, so reducing Na+ reabsorption
MOA of carbonic anhydrase inhibitors
Reduces HCO3+ reabsorption so weakly reduces water reabsorption
