Drug Action 2 Flashcards
What are the two most common NSAIDs?
Aspirin and paracetamol
What are the benefits of aspirin over paracetamol?
Anti-platelet action, reduced risk of colonic and rectal cancer, reduced risk of Alzheimer’s, it’s a weak acid - rapid and efficient absorption in the ileum
What are the disadvantages of aspirin over paracetamol?
Aspirin is an irreversible suicide inhibitor
What are the benefits of paracetamol over aspirin?
Weak anti-inflammatory, COX-2 selective, well absorbed and metabolised in the liver, fewer side effects long term
What are the disadvantages of paracetamol over aspirin?
Kidney damage in large acute doses, n-acetyl-p-benzoquinoneimine is hepatoxic, it’s a competitive inhibitor
What are the new NSAIDs?
Celecoxib and rofecoxib
Which type of COX is involved with inflammatory response?
COX-2
Which NSAID forms a metabolite that damages the liver?
Paracetamol
What is rheumatoid arthritis?
Incurable common chronic inflammatory and destructive arthropathy that typically affect synovial joints
What is the average onset and incidence of rheumatoid arthritis?
70 years, can be much younger, 1% of UK population
How much does RA cost the UK per year?
3.4-8.75 billion
What does RA stand for?
Rheumatoid arthritis
What is the prognosis for RA patients?
Poor - 80% disabled after 20 years, life expectancy reduced by 3-18 years
What disease presents with three or more warm, swollen joints, with stiffness in the morning?
RA
What nine symptoms can lead to a positive diagnosis of RA?
Three or more warm, swollen joints; stiffness in the mornings; arthritis of hand joints; symmetrical arthritis; presence of rheumatoid nodules; fatigue; fever; tiredness; presence of rheumatoid factor
What are rheumatoid nodules?
Firm tissue bumps under the skin on the arms
What occurs in synovial joints during early RA?
Synovial membrane becomes hyperplastic and synoviocytes become hypertrophic; an immune response is launched and neutrophils, T cells and B cells descend
What would hyperplastic synovial membranes and hypertrophic synoviocytes lead to?
RA
What do chondrocytes produce?
Cartilage
What do fibroblasts produce?
ECM components
What do osteoclasts produce?
Involved in bone absorption during growth
What two cytokines are involved in RA?
IL-1 and TNF-alpha
What condition are IL-1 and TNF-alpha involved in?
RA
Where is IL-1 produced?
Monocytes, macrophages and other cells
What three kinds of IL-1 exist?
Alpha, beta and ra
What response does IL-1 evoke?
Proinflamamtory
What does IL-1 stimulate the release of?
Matrix metalloproteinases from fibroblasts and chondrocytes
What stimulates the release of metalloproteinases?
IL-1
Where is TNF-alpha produced?
Macrophages, monocytes and mast cells
What response does TNF-alpha evoke?
Proinflammatory
Why does blocking TNF-alpha have more profound effects than blocking other cytokines?
It induces other pro-inflammatory cytokines so blocking TNF-alpha can simultaneously block many other cytokines
What does TNF-alpha stimulate the release of?
Metalloproteinases from chondrocytes
What are DMARDs?
Disease-modifying antirheumatic drugs
What are DMARDs used for?
May be useful in limiting the progression of disease
What is methotrexate?
DMARD - folic acid antagonist
What does methotrexate do?
Reduces antigen activated T-cell proliferation
What secondary function is methotrexate known to perform?
Promote adenosine release and adenosine-mediated suppression of inflammation
What is the primary difference between methotrexate and other DMARDs?
Superior in terms of efficacy, unwanted effects and rapid onset
Why must methotrexate treatment be closely monitored?
High incidence of blood and liver toxicity
What is sulfasalazine used to treat?
RA
What effect does sulfasalazine have on active RA?
Remission
What is sulfasalazine a complex of?
Sulphonamide and salicylate
What does a complex of sulphonamide and salicylate form?
Sulfasalazine
What does MOA stand for?
Method of action
What is the MOA of sulfasalazine?
Scavenges toxic oxygen metabolites produced by neutrophils
What are the three main classes of immunosuppressant drugs for RA?
IL-2 production/action inhibitors, cytokine gene expression inhibitiors, purine/pyrimidine synthesis inhibitors
Describe ciclosporin’s structure.
Naturally occuring 11 a/a cyclic peptide found in fungus
What does ciclosporin do?
Decrease clonal proliferation of T cells by inhibitting IL-2 synthesis and decreasing expression of IL-2 receptors
Where is ciclosporin metabolised and excreted?
Liver and mainly excreted in bile
What are the side effects of ciclosporin?
Nephrotoxicity, hepatoxicity and hypertension
Name a drug that inhibits IL-2 production and action.
Ciclosporin
What is the primary function of glucocorticoids?
Anti-inflammatory and immune suppression
How do glucocorticoids work?
Transciptional inhibition of cytokines including - IL-1,2,6 and TNF
What other activities do glucocorticoids perform?
Inhibition of adhesion molecule expression, arachidonic acid metabolism, metalloproteinase production
Name a family of drugs that inhibits cytokine gene expression.
Glucocorticoids
What two drugs inhibit purine and pyrimidine synthesis in RA treatments?
Azathioprine, mycophenolate mofetil
What does azathioprine do?
Inhibits DNA synthesis through its active metabolite mercaptopurine
What is the active ingredient in azathioprine?
Mercaptopurine
What side effects are associated with azathioprine and mycophenolate mofetil?
GI side effects
What extra side effect does azathioprine have over mycophenolate mofetil?
Mild hepatotoxicity
What does mycophenolate mofetil do?
Inhibits DNA synthesis through inhibition of de novo urine synthesis
What are anticytokine drugs?
Engineered recombinant antibodies and other proteins that target specific aspects of RA and other inflammatory diseases
What are some anticytokine drugs co-administered with?
Methotrexate
What are the three mechanisms of anticytokine drugs?
Neutralisation of cytokines, receptor blockade and activation of antiinflammatory pathways
How do anticytokine drugs neutralise cytokines?
Cytokine is prevented from binding to cell-surface receptor by soluble receptor or monoclonal anti-body attachment to the cytokine
How do anticytokine drugs peform receptor blockade?
Antagonistic occupation of receptor or monoclonal antibody attachment to the receptor, blocking binding site
Name five anticytokine therapies.
Etanercept, infliximab, anakinra, abatacept, efalizumab
At what indication are anticytokine therapies prescribed to RA sufferers?
Moderate-severe
What type of anticytokine therapy is etanercept?
Fusion protein
What type of anticytokine therapy is infliximab?
Chimeric antibody
What type of anticytokine therapy is anakinra?
Recombinant protein
What type of anticytokine therapy is abatacept?
Fusion protein
What type of anticytokine therapy is efalizumab?
Humanised monoclonal antibody
What is the target cytokine for etanercept?
TNF - by decoy receptor
What is the target cytokine for infliximab?
TNF - by neutralisation
What is the target cytokine for anakinra?
IL-1 - by receptor agonism
What is the target cytokine for abatacept?
B7 - by antigen presentation in cells
What is the target cytokine for efalizumab?
CD11a - neutralises leukocytes
What drug therapies can nausea and vomiting be side-effects of?
Cytotoxic chemotherapy, opioids, general anaesthetics and digoxin
What endogenous stimuli can cause nausea and vomiting?
Motion sickness, morning sickness, numerous disease states, migraine, ingestion of toxins, fear, pain and olfactory stimuli
What antagonists can block emetic effects?
5-HT-3 anatagonists
What can 5-HT-3 antagonists do?
Block the emetic effects of cytotoxic drugs used during cancer chemotherapy
What two main pathways supply visceral sensation?
Vagal and spinal
Which of the two pathways of visceral sensation supplies mainly physiological stimuli?
Vagal
Which of the two pathways of visceral sensation supplies mainly noxious stimuli?
Spinal
Where do vagal cell bodies of the visceral sensation pathway reside?
Nodose ganglia
Which visceral sensatory cell bodies lie in the nodose ganglia?
Vagal
Where do spinal cell bodies of the visceral sensation pathway reside?
Dorsal root ganglia
Which visceral sensatory cell bodies lie in the dorsal root ganglia?
Spinal
What two systems does the spinal visceral sensatory pathway split into?
Splanchnic and pelvic
Describe the vagal 5HT-3 receptor.
Pentameric ligand gated ion channel - subunits 5HT-3A to 5HT-3E
Can 5HT-3 form a homomeric complex? If so, of which subunit?
Yes - 5HT-3A
What are the most studied 5HT-3 receptors?
Heteromeric 5HT-3A/B
What is the ionic activity about a 5HT-3 receptor?
K out, Na and Ca in
What are EC cells?
Enterochromaffin cells
What cells are responsible for sensory transduction in the gut?
Enterochromaffin cells
What proportion of the body’s serotonin is found in the gut?
95%
Where is 95% of the body’s serotonin found?
The gut
In what cells is serotonin found in the gut?
EC cells, enteric neurons and mast cells
What are the setron family of drugs?
Antiemetics - 5HT-3 receptor antagonists
Name three first generation setron family drugs.
Granisetron, ondansetron and tropisetron
What kind of drug is gransetron?
Anti-emetic - setron family - 1st generation 5HT-3 receptor antagonists
What kind of drug is ondansetron?
Anti-emetic - setron family - 1st generation 5HT-3 receptor antagonists
What kind of drug is tropisetron?
Anti-emetic - setron family - 1st generation 5HT-3 receptor antagonists
How do 1st generation setron family drugs function?
Competitive antagonists at both peripheral and central 5HT-3 receptors
What are 1st generation setron family drugs usually used to treat?
Acute chemotherapy-induced emesis; not very good at treating delayed emesis
Name one second generation setron family drug.
Palonosetron
What is different about second generation setron family drugs?
Effective in preventing both acute and delayed emesis; believed to act through allosteric mechanisms causing receptor internalisation
What are NK-1 receptors, and what are they activated by?
Neurokinin receptors - tachykinin peptides
What is the order of potency of tachykinin peptides?
Substance P > NK A > NK B
What is a strong alternative to the setron family anti-emetics?
NK-1 receptor antagonism
Name one NK-1 receptor antagonist.
Aprepitant
What family of drugs does aprepitant belong to?
NK-1 receptor antagonists - anti-emetics
What is hyoscine also known as?
Scopolamine
What type of drug in hyoscine?
Anti-emetic
What receptors does hyoscine act upon?
mAChR
What is the indication for hyoscine?
Motion sickness
What are the side effects of hyoscine?
Drowsiness, dry mouth, blurred vision
What type of drug is chlopromazine?
Anti-emetic
What type of drug is perphenazine?
Anti-emetic
What type of drug is prochlorpenazine?
Anti-emetic
What type of drug is trifluoperzine?
Anti-emetic
What receptor does chlopromazine act upon?
Dopamine antagonists (D2)
What receptor does perphernazine act upon?
Dopamine antagonists (D2)
What receptor does prochlorpenazine act upon?
Dopamine antagonists (D2)
What receptor does trifluoperzine act upon?
Dopamine antagonists (D2)
What is the indication for chlopromazine?
Severe cases of chemo/radio therapy or pharmacologicaly induced emesis
What is the indication for perphenazine?
Severe cases of chemo/radio therapy or pharmacologicaly induced emesis
What is the indication for prochlorpenazine?
Severe cases of chemo/radio therapy or pharmacologicaly induced emesis
What is the indication for trifluoperzine?
Severe cases of chemo/radio therapy or pharmacologicaly induced emesis
What are the side effects of chlopromazine?
Sedation, hypotension, dystonias, tardive dyskinesia
What are the side effects of perphenazine?
Sedation, hypotension, dystonias, tardive dyskinesia
What are the side effects of prochlorpenazine?
Sedation, hypotension, dystonias, tardive dyskinesia
What are the side effects of trifluoperzine?
Sedation, hypotension, dystonias, tardive dyskinesia
What type of drug is metaclopromide?
Anti-emetic
What receptor does metaclopromide act upon?
Dopamine antagonists (D2)
What is the indication for metaclopromide?
Increases gut motility and acts on CTZ
What does CTZ stand for?
Chemoreceptor trigger zone
What type of drug is domperidone?
Anti-emetic
What type of drug is cinnarizine?
Anti-emetic
What type of drug is cyclizine?
Anti-emetic
What type of drug is promethazine?
Anti-emetic
What receptor does domperidone act on?
Dopamine antagonists (D2)
What receptor does cinnarizine act on?
Histmamine antagonists (H1)
What receptor does promethazine act on?
Histmamine antagonists (H1)
What receptor does cyclizine act on?
Histmamine antagonists (H1)
What is the indication for domperidone?
Cytotoxic therapies
What is the indication for cinnarizine?
Motion sickness
What is the indication for cyclizine?
Motion sickness
What is the indication for promethazine?
Motion sickness
What are the side effects of cinnarizine?
Drowsiness, fatigue
What are the side effects of cyclizine?
Drowsiness, fatigue
What are the side effects of promethazine?
Drowsiness, fatigue
Name six D2 antagonistic anti-emetics.
Chlopromazine, perphenazine, prochlorpenazine, trifluoperzine, metaclopromide, domperidone
Name three H1 antagonistic anti-emetics.
Cinnarizine, cyclizine, promethazine
What family of drugs is gathering evidence as anti-emetic?
Cannabinoids
What family does the CB1 receptor belong to?
Endocannabinoid family
What does CB1 agonism prevent?
Emesis
What is emesis?
Vomiting
What does CB1 inverse agonism cause?
Emesis
Name two excitatory a/a NTs.
Glutamate, aspartate
Name two inhibitory a/a NTs.
GABA, glycine
What does GABA stand for?
Gamma-aminobutyric acid
What seven characteristics define glutamate receptors?
Subunit, composition, pharmacology, time course, Ca permeability, distribution and neuronal function
Characterise AMPA receptor Ca permability, and why they have evolved.
Low Ca permability, evolved for rapid depolarisation of cells
Characterise GABA-A receptors.
Post-synaptic, choride selective ionotropic receptors
What do GABA-A receptors do?
Mediate fast inhibitory transmission
How many units comprise GABA-A receptors?
5
What is the orthosteric GABA-A agonist?
Muscimol
What are the orthosteric GABA-A antagonists?
Bicuculline, picrotoxin
What is the allosteric GABA-A agonist?
Diazepam
What is the allosteric GABA-A antagonist?
Flumazenil
What does the allosteric GABA-A site do?
Increases or decreases strength of response
Which GABA-A site does muscimol bind to? Agonist or antagonist?
Orthosteric agonist
Which GABA-A site does bicuculline bind to? Agonist or antagonist?
Orthosteric antagonist
Which GABA-A site does picrotoxin bind to? Agonist or antagonist?
Orthosteric antagonist
Which GABA-A site does diazepam bind to? Agonist or antagonist?
Allosteric agonist
Which GABA-A site does flumazenil bind to? Agonist or antagonist?
Allosteric antagonist
Characterise GABA-B receptors.
Pre and post-synaptic G-i/o protein coupled receptor
What do GABA-B receptors do?
Mediate slow transmission
Inhibiton of which channels causes pre-synaptic inhibition?
Ca-v channels
Activation of which channels causes post-synaptic inhibition?
K channels (GIRK)
Name a GABA-B agonist.
Beclofen
Name a GABA-B antagonist.
Phaclofen
What is baclofen?
GABA-B agonist
What is phaclofen?
GABA-B antagonist
What does GIRK stand for?
G-protein-coupled inwardly-rectifying K channel
What six drug types target GABA-A receptors?
Sedatives, anxiolytics, hypnotics, anti-convulsants, neurosteroids and some general anaesthetics
What is the general structure of GABA-A receptors?
2 alpha, 2 beta and 1 ‘other’ subunit (usually gamma)
Which superfamily does the GABA-A receptor belong to?
Nicotinic
What are the five physiological effects of benzodizepine agonists?
Sedation, hypnosis, anterograde amnesia, anti-convulsant, reduction of muscle tone
What determines the use of benzodiazepine agonists?
Pharmacokinetics
Which benzodiazepines are used mainly as sleeping tablets?
Short acting
What can intravenous diazepam be used to treat?
Status epilepticus
Why have some benzodiazepines have such long half lives?
Metabolized in the liver to produce active intermediates
What five key adverse effects can benzodiazepine agonists cause?
Sleepiness, impaired psychomotor function, amnesia, additive effects, tolerance, misuse, dependence
What ‘additive effects’ can occur with benzodiazepine agonists?
Combinative effects with other CNS depressants - can be fatal
Define drug tolerance.
Decreased responsiveness to a drug following continuous exposure
What must physical dependence be characterised by?
Withdrawal - increased anxiety, insomnia, CNS excitability, convulsions
How would you alleviate physical withdrawal?
Use a slower acting drug