Pharmacology Flashcards
What are the effects of Local anaesthetics?
- Slow rate of depolarization.
- Slow axonal conduction
- Increase threshold potential.
- Reduce height of action potential.
- No effect on RMP
“SSIR No”
What is the mechanism of action for local anaesthetics?
Physical blockade of voltage gated Na+
What happens when local anaesthetics provides a physical blockade for Na+ channels?
Blockade Increase Na+ channel recovery time (10-1000 times)= prolonged refractory period Ultimately prevent propagation of AP
What are examples of Esters?
Please - Procaine
Bring - Benzocaine
The- Tetracaine( Amethocaine)
Cocaine
” Please bring the cocaine”
What are examples of Amides?
Roy - Ropivacaine
Brought - Bupivacaine
Pain - Prilocaine
Medication - Mepivacaine
Late- Lignocaine
Which local aesthetic drugs are weak bases (pKa 8-9) (poor solubility in water) & given as HCl salts, water soluble?
Procaine
Lignocaine
Benzocaine
Where is the receptor site for local anaesthetics located?
On the innerside of the membrane
True or False? Local anaesthetics bind most avidly to the activated state of sodium channels.
FALSE!! They bind most avidly to the INACTIVATED state .
True or False? The greater the firing frequency of an axon, the greater the blockade.
TRUE!!
True or False? Local anaesthetics DOES NOT promote hyperpolarization.
TRUE!!
Why do local anaesthetics have no effect on the resting membrane potential?
This is because the resting membrane potential; is controlled by the sodium potassium ATP-ase NOT Voltage- gated Sodium channels
True or False? In regards to local anaesthetics, The larger the diameter of the nerve the greater the susceptibility.
FALSE!! The smaller the diameter of the nerve the greater the susceptibility
Which fibers are most sensitive to block for local anaesthetics?
Type C fibres
True or False? The closer the pka is to 7.4 , the faster the onset of the drug.
TRUE!!
What are factors that will affect the use of local anaesthetics?
- Acidic environment facilitates the population of the charged form
- Basic environment is low in H ions and facilitates the free base
True or False? Local Anaesthetics does NOT react faster if there is inflammation at the site.
TRUE!! Local anaesthetics does NOT react faster if there is a site of inflammation due to its acidic environment so the antilog is MORE and there will be less BASE form so the drug will work less and even have more adverse effects .
Which local anaesthetic drug was the first to be discovered?
Cocaine was the first local anaesthetic drug to be discovered
By what process do local anaesthetics enter the body through?
Passive diffusion
Which local anaesthetic drug is applied ONLY Topically ?
Benzocaine
By what enzyme are Local Anaesthetics (ESTERS) metabolised & eliminated?
By the enzyme plasma pseudocholinesterases to produce Para-aminobenzoic acid (PABA).
True or False? Local anaesthetics ( AMIDES) are metabolised through the kidneys.
FALSE!! Hepatic metabolism so liver
Which Local anaesthetic ( ESTERS) is NOT metabolised by the enzyme plasma pseudocholinesterases to produce Para-aminobenzoic acid (PABA)?
COCAINE- It goes through Hepatic metabolism
Which local aesthetic drug is associated with causing Methemoglobinaemia due to production of toluidine on metabolism?
Prilocaine
Allergic reactions are seen with which type of local anaesthetics?
Esters - due to PABA from metabolism.
Fill in the blanks. “ Most local anaesthetics are vasodilators EXCEPT ___________ which is a Vasoconstrictor.”
Cocaine = Vasoconstrictor
What are the adverse effects of Cocaine?
CV= -vasoconstriction, increase BP, Arrhythmias
CNS = Euphoria
True or False? Esters EXCEPT cocaine have a longer duration than Amides.
FALSE!! Esters ( EXCEPT Cocaine) has a SHORTER duration.
Which type of local aesthetic has a Greater potency and a less vasodilation potential?
Amides
Which drug is used only topically for anaesthesia of the respiratory tract as 1%, 4% or 10% solution?
Cocaine
Which Local Anaesthetic drug is used rectally for itching & pains associated with hemorrhoids
Itching and pains associated with sunburns etc?
BENZOCAINE
Which Local anaesthetic drug is mainly used WITH a vasoconstrictor ?
Lignocaine
Which local anaesthetic can be used without a vasoconstrictor ?
Prilocaine
Which Opioid receptor mediates the most actions of Opioids?
Mu receptor
What are examples of Strong Opioid Agonists?
Morphine
Meperidine (Pethidine)
Oxymorphone
Methadone
Forgot - Fentanyl,
Henry - Hydromorphone
Loves - Levorphanol
Heroin
” MMOM Forgot Henry Loves Heroin”
What are examples of a Moderate or Weak Opioid Agonist?
Betty - Buprenorphine
Hates - Hydrocodone
C- Coedine
O- Oxycodone
P- Propoxyphene
s
Which drug is one of the few Opioids drugs used to treat coughing?
Codeine
Which drug us a Synthetic analogue of Codeine?
Tramadol
What is the Mechanism of action for Tramadol?
- Weak Mu receptor agonist
- Inhibition of reuptake of serotonin and NE
What are the adverse effects of Tramadol?
- Dizziness, constipation, NV, headache, somnolence
- Pruritus, CNS stimulation ( nervousness, anxiety, agitation, mood swings, hallucinations)
- Increase risk of seizures with SSRIs, TCAs
Which drug is a derivative of Levorphanol?
Dextromortophan - cough suppressant
Diphenoxylate is a derivative of what drug and what is its function ?
Pethidine- used to treat diarrhoea
Which drug is derivative of pethidine used to stimulate Mu receptors in myenteric plexus → anti-diarrhoeal action ,used to treat diarrhoea and does not cross BBB, hence no analgesic effect?
Loperamide
What are Mixed Agonist- Antagonists of Opioids?
Pentazocine
Nalbuphine
Butorphanol
What is used to treat Opioid overdose?
Naloxone & Naltrexone
What is the MOA of Morphine?
Binds primarily to Mu receptors.
both reducing neurotransmitter release from presynaptic nocieptive neurons (via ↓Ca 2+ entry) and hyperpolarizing & thereby inhibiting postsynaptic neurons (via ↑K+ conductance)
What are the clinical uses of Morphine?
H- Histamine release
E- Emesis
C- Contraction of smooth muscle in biliary tract, bladder & ureter ( increase ADH release —-> urinary retention)
k
of
a
D- Decreased cough reflex
D- Decreased GI motility
D- Decreased uterine tone
D - Depression of mental functioning.
R- Respiratory depression
E- Euphoria
A- Analgesia
M- Miosis
What are the withdrawal symptoms of Morphine?
Lacrimation
Rhinorrhoea
Sweating
Gooseflesh
Nausea
Tachypnoea
A triad of coma, pinpoint pupils ,respiratory depression indicates an overdose of which drug?
Morphine
Which adjuvant medications may be administered with morphine to reduce adverse effects?
Anti-emetics
Laxative
Which Opioid agonist is widely used in labour & post-op pain management?
Pethidine (Meperidine)
At what time duration does Morphine withdrawal symptoms peak?
36-72 hours
True or False? Fentanyl is more potent than Sufentanil.
FALSE!! Sufentanil 5x more potent than fentanyl.
Which Opioid agonist is used in the treatment of Opioid withdrawal symptoms particularly in cases of heroin dependence?
Methadone
Which Weak Opioid agonist is Obtained naturally or by methylation of morphine?
Codeine
Which enzyme is responsible for the demethylation of Codeine & what type of people are it absent in?
CYP2D6 enzyme - It is absent in 7% Caucasian pop. → these persons will derive little benefit from codeine .
What are the adverse effects of Codeine?
Constipation
Somnolence ( feeling sleepy) , Nausea
Vomiting
Respiratory depression only at very high doses.
Which Opiod drug is a Agonist at Kappa receptors and partial agonist at Mu receptors?
Pentazocine
What are the adverse effects of Pentazocine?
Anxiety
Unpleasant dreams
Hallucinations
Nausea
Sweating
What is the MOA for Tramadolol?
- Weak Mu receptor agonist
- Inhibition of reuptake of serotonin and NE
Which drug can have an increased risk of seizures with SSRI’s and TCA’s?
Tramadol
True or False? Naloxone has a longer duration of action than Naltrexone.
FALSE!! Naltrexone has a longer duration of action .
Naloxone- 1-2 hrs
Naltrexone- 48 hr
What are the adverse effects of Naltrexone?
- Hepatotoxicity
- Nausea
*Sedation - Headache
What are the adverse effects of Naloxone?
- Tachycardia
- Arrhythmias
Which Local aesthetic ( Esters) is used only for Infiltration Anaesthesia?
Procaine
Which Local anaesthetic drugs can be infiltrated ( Direct injection into tissues to act on a local nerve ending
Given with epinephrine except in tissue with end- arteries(fingers, toes, penis) ?
Lignocaine
Procaine
Bupivacaine
Which local anaesthetics can be applied Topically?
Tetracaine
Lignocaine,
Cocaine
Benzocaine
