SBT - Scientific Basis of Therapeutics Flashcards
What is inflammation
- Bodys defensive response to
- Invasion (pathogens that cause disease) (allergens - non disease)
- Injury - heat, ultraviolet, chemicals
- Signs are that there is:
• Calor (warmth, increased blood flow),
• Rubor (redness, increased blood flow),
• Dolor (pain, sensitisation/activation of sensory nerves),
• Tumour (swelling, increased post ),
• Functio laesa (loss of function, pain/injury) - Inflammation is production by both innate and adaptive immune systems
- Clinically these are important processes
- Chronic inflammation - severe tissue damage, e.g. atherosclerosis
- Acute responses - anaphylaxis, sepsis
- ## Anti inflammatory drugs are regularly prescribed
Histamine characteristics ?
- Synthesised from histindine amino acid, by histidine decarboxylase
- Metabolised from imidazole N methyltransferase (IMNT) + diamine oxidase
- Synthesised and stored, released from
• Mast cells, which express receptors for IgE, C3a, and C5a on cell surface (connective tissue)
• Basophils (blood)
• Neurones in brain
• Histaminergic cells in gut - Pre made, ready to go, in secretory granules that are made up of heparin and acidic proteins
- Released by allergic reactions (IgE mediated)
- Production of complement agents C3a, C5a, insect stings, trauma via a rise in [Ca2+]I
- Release of histamine inhibited by stimulated of beta adrenoreceptors
Histamine receptors characteristics - H1
- Gq/PLC, PIP2 production
- Generation of DAG + IP3
- Smooth muscle
- Endothelium
- CNS
Histamine receptors characteristics - H2
- Gs/AC, generation of cAMP
- Stimulation of PKA
- Parietal cells to increase gastric acid secretion, heat
Histamine receptors characteristics - H3
- Gi, decreases Camp levels
- Neuronal presynaptic terminals
Histamine receptors characteristics - H4
- Gi, decreases in cAMP levels
- Basophils, bone marrow, gut
What are the effects of stimulating the H1 and H2 receptors - Cardiovascular effects
- Dilates the arterioles, causes a fall in the TPR (H1)
- Increased permeability of post-capillary venules, ¯BV (H1)
- Increase in heart rate (H2) - in vivo reflex to try to retain BP to normal
- Generally involved in ¯BP (↓ vascular resistance)
What are the effects of stimulating the H1 and H2 receptors - Non vascular smooth muscle, airways and gut
- Contraction (H1), e.g. bronchoconstriction
What are the effects of stimulating the H1 and H2 receptors -Algesia
- Pain, itching, and sneezing caused by stimulation of sensory nerves (H1)
What are the effects of stimulating the H1 and H2 receptors - Gastric acid
- Increase secretion (H2)
What are the effects of stimulating the H1 and H2 receptors - Associated exocrine secretions
- Increased, due to blood flow
What are the pathological roles of histamine
- Acute inflammation
2. Stimulating gastric acid secretion
Acute inflammation Triple response:
- Reddening (local vasodilation)
- Wheal
Flare
What is antidromic impulse
- Antidromic impulse refers to impulse conduction along the nerve fibre in a direction that is opposite of normal direction (orthodromic)
- It is conduction along the axon away from axon terminal towards the cell body
- Antidromic impulses in nerve fibres may be produced by electrical stimulation.
- Antidromic impulses release neuropeptides which case vasodilation distant from the site of irritation → the third phase of inflammation, the flare response
Lewis triple response characteristics
- 3 part response when a line is drawn on the skin , due to a release of histamine from the mast cells
• Degranulation of mast cells
• Changes in smooth muscle contractility
• Stimulation of lymphocytes and granulocytes → neurogenic inflammation - Flare: kinin, neurotensin, or substance P, implicated in the chain of biochemical events
describe Dermatographia in the triple response
- Reddening: oedema [↑ vascular permeability induced by substance P (SP) and histamine → ↑leakage of fluid and plasma proteins from capillaries (ie.e, ↑ plasma proteina extravasation)]
H1 antagonists that treat acute inflammation characteristics - 1st gen
- Mepyramine
- Diphenhydramine
- Promethazine
H1 antagonists that treat acute inflammation characteristics - 2nd + 3rd gen
- Terfenadine, prodrug which potential cardiac arrhytmia action in high concentration. These are increased with grapefruit juice
- Grapefruit juice inhibits P450 mediated drug metabolism with liver pathways
• Fexofenadine, active, non toxic metabolite of terfenadine
H1 antagonists that treat acute inflammation characteristics - Therapeutic and side effects
- Reduce minor inflammatory reactions, like insect bites and hay fever - but there is no significant value in asthma
- 1st generation drugs are sedative - drowsiness is a major side effect, but sometimes is used as a therapeutic effefct
- Some, like promethazine are antiemetic = motion sickness
- Anti muscarinic actions (common in first generation drugs), like atropine like effects of blurred vision, constipation etc.
Gastric problems that can arise because of H2 antagonists
- Archetypal - cimetidine, ranitidine
- Therapeutic and side effects:
• Reduces gastric acid secretion in treatment of duodenal and gastric ulcers and Zollinger-Ellison syndrome (duodenum & pancreas tumours increasing gastrin secretion)
Increase INMT activity so more rapid breakdown of histamine
Mental confusion, dizziness, tiredness & diarrhoea sometimes as side effects
Cimetidine, decrease in cytochrome P450 activity so adverse drug interaction potential, gynecomastia
Describe the synthesis of Bradykinin
The generation of bradykinin as a result of activation of:
- Hageman factor (HF) & production of plasma kallikrein
- Production of lysylbradykinin by tissue kallikreins;
- Action of cellular proteases in kinin formation
What is the Hageman factor
Hageman factor = coagulation factor XII
What are the pharmacological effects of bradykinin
- Potent vasoactive peptides
- Increase vascular permeability
- Vasodilation (↓BP)
- Pain
- Contraction of smooth muscle (gut and bronchus)
- Stimulation of arachidonic acid metabolism (initiates phospholipase action)
- Chemotactic to leukocytes, which defend the body against infections
- Dry cough
- Metabolism of bradykinin: kininases (ACE, aminopeptidase P, carboxypeptidase)
Describe the distribution of 5HT
- Platelets release 5HT, and TXA2
- The ECL cells of the GI tract, mediates gut movement, diarrhoea,
- Brain (congition, aggression, mating, feeding, sleep, pain, vomiting, behaviour)
- Some tumours (e.g. carcinoid) - secrete excess 5HT
What are the inflammatory actions of 5HT
- Stimulates mast cell adhesion and migration
- 5HT enhances inflammatory reaction of the skin, lungs and gut
- Promotes inflammation by increasing number of mast cells at the site of tissue injury
- Might synergise with TXA2 to stimulate platelet activity and vasoconstriction
- Activation of TXA2 receptors increases 5HT mediated responses in the blood vessels
Prostaglandins, Thromboxanes, Leukotrienes (PTL) - what are they known as
- Eicosanoids
Important of the PTL, eicosanoids
- They are molecules that have powerful inflammatory actions
- Targets of major anti inflammatory drugs:
• NSAIDS, glucocorticoids, Lipoxygenase inhibitors, Leukotriene antagonists - We need to know how the PTL Eicosanoids are made
How the Prostanoids are made (Prostaglandins and Thromboxanes) - not leukotreines
- Prostanoids are not ‘ready-to-go’ (unlike histamine)
- Prostanoids are generated from arachidonic acid (AA, poly-unsaturated fatty acid). This is rate-limiting step
- AAs are produced from phospholipids (PLs) via 1-step/2-step pathways
- These steps are triggered by many agents, e.g. thrombin on platelets and antigen-antibody reactions on mast cells
- Bradykinin and adrenaline are known initiators of the cascade and can initiate phospholipase action at the cell membrane.
- Noradrenaline changes the distribution profiles of eicosanoids
What initiates the formation of prostanoids (prostaglandins and thromboxane)
- Bradykinin + adrenaline
Cyclooxygenases
general action
- Conversion of AA into prostanoids needs COX (cyclooxygenase enzyme)
- COX1/COX2 are the 2 main isoforms
- COX are fatty acids that are attached to the endoplasmic membrane
COX 1 actions
- Constitutively active, responsible for the physiological roles of PGs/TXs like the regulation of peripheral vascular resistance
- Renal blood flow, platelet aggregation, gastric cytoprotection
COX 2 actions
- Needs to be stimulated
- e.g. by inflammatory cytokines (IL-1), TNFalpha
- Responsible for role of prostaglandins/TX in inflammatory responses - pain and fever
COX 3 actions
- COX1 variants
- Pain perception of the CNS
Anti-inflammatory lipid mediators - lipoxins and CyPGs
- There is a switch for PG synthesis from pro-inflammatory (PG & LTs) at onset of inflammation to anti-inflammatory lipoxins and 15dPGJ2 (cyPG) during resolution
- Activation of monocytes is important in their action
• Lipoxins recruit monocytes to clear inflamed site of necrotic apoptotic neutrophils - Regulate activation levels of neutrophils and dampen their damaging effects (↑phagocytosis of neutrophils)
- By acting in concert with cyPGs,
- Promote phagocytic clearance of apoptotic cells by macrophages → resolution of inflammation
- CypG – inhibits macrophage activation→ ↓ uncontrolled tissue damage; ↓NF-kβ activation (helps to ↓ activation of inflammatory genes)
Actions of eicosanoids as local hormones?
- Cells specialise in making particular eicosanoids
- mast cells: PGD2
- platelets: TXA2
- endothelial cells: PGI2, PGE2
- Act at specific G-protein-coupled receptors
- PGs subtypes act at DP, FP, IP and EP (EP1, EP2, EP3) receptors
- TXs at TP receptors
- LTs : LTB4 at BLT receptors; LTC4, LTD4 & LTE4 at Cys-LT receptors (-chemotactic; bronchoconstrictor & ↑ vascular permeability; oedema, ↑secretion of thick, viscous mucus)
Exert diverse and often contradictory actions in inflammation
Subjected to local inactivation
Physiological/Pathological actions of Eicosanoids
- PGs (Lungs, vascular, gut, CNS, kidney, uterus)
DP receptors: Vasodilatation, ¯ platelet aggregation, bronchoconstriction
FP receptors: Contraction of myometrial smooth muscle, bronchoconstriction
IP receptors: Vasodilatation, ¯ platelet aggregation, renin release
EP1 receptors: Contraction of bronchiole/GIT smooth muscle
EP2 receptors: Bronchodilation, vasodilatation, relaxation of GIT smooth
muscle, intestinal fluid secretion
EP3 receptors : Contraction of intestinal smooth muscle, gastric mucus secretion, ¯ gastric acid secretion, pyrexia
TXs (vascular/platelets)
TP receptors: Vasoconstriction, platelet aggregation
LTs (General inflammation, lungs/vascular in acute allergy responses)
BLT (1 & 2) receptors: Chemotaxis and proliferation of immune cells, adhesion
CysLT (1 & 2) receptors: Bronchoconstriction, vasodilatation, vascular permeability
Leukotriene receptor antagonists
- Examples: Zafirlukast, montelukast, pranlukast, zileuton
- Block receptor for cysteinyl LTs (LTC4, LTD4, LTE4, etc)
- These LTs cause airway oedema, secretion of thick mucus and smooth muscle contraction
- Receptor blockade is useful in following:
• Prevention of mild to moderate asthma
• Early to late bronchoconstrictor effects of allergens
• Exercise-induced asthma and asthma provoked by NSAIDs
• Side effects: GI upset, Irritability, Dry mouth, thirst, rashes, oedema
Measurement of effects of mediators that cause bronchospasm
- Comparing SRSA (LTD4, LTC4 , LTE4) with histamine in the lung
- Effects of LTC4, LTD4 and histamine on the contraction of guinea pig lung strip: a section of peripheral lung tissue
- Summary of results: Leukotrienes are much more potent than histamine
Poly unsaturated fat intake in disease
- The poly-unsaturated fatty acids (PUFAs; omega-3 essential fatty acids) are of considerable interest because of their (perceived) beneficial effects for our health
- Substances such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish oils play a significant part in inflammation
- Derivatives of EPA and DHA (resolvins and neuroprotectins, respectively) have anti-inflammatory actions
Poly unsaturated fat acids in inflammation
- Fish oils provide substrates for the generation of alternative eicosanoids
- Fish oils cause increased proportion of ecosapentanoic acid (EPA) and docosahexaenoid acid (DHA) in inflammatory cells at the expense of AA
- Less substrate (i.e., AA) is available, therefore there is ↓ production of PGE2, TXB2, LTB4, 5-HETE, LTE4
- Thus EPA and DHA act as substrates for the generation of alternative eicosanoids
What is the consequence of interaction of EPA with COX/LOX?
Consequence of interaction of EPA with COX/LOX:
↑ LTB5, LTE4, 5-HPETE - eicosanoids of different structure to those generated from AA
LTB5 is 10-100 less chemotactic to neutrophils
Anti-inflammatory metabolites of EPA and DHA
- A novel group of mediators have also been identified from COX-mediated action on EPA and DHA.
- E-series resolvins (resolvin D1-D4; EPA-derived mediators) have anti-inflammatory actions.
- Docosatrienes and neuroprotectins (D-series resolvins; DHA-derived mediators) also have anti-inflammatory effects.
Mechanism of action of PUFAs (EPA and DHA)
- Overall, specialized counter-regulatory lipid mediators (lipoxins, resolvins, protectins and cyPG) initiate the resolution of inflammation in vivo and in vitro animal models.
Which enzymes are responsible for the formation of leukotrienes?
- Lipoxygenase is the enzyme that is responsible for leukotreines
What are the effects of Bradykinin on vascular smooth muscle cells
- Increases vascular permeability
- Vasodilation
- Contraction of gut + bronchial smooth muscle cells
- Causes secretion of TXA2, which will increases platelet aggregation
- TXA2 also causes contraction of smooth muscle cells - vasoconstriction
What are the effects of 5HT serotonin on vascular smooth muscle cells
- Promotes TXA2 - promotes platelet aggregation
- Release from endothelial cells
- Promotes mast cell number @ inflammatory sites, etc.
Prostaglandins have protective effects on the gut. Which prostaglandin mediates protective effects, the receptor it interacts with and the types of effects that it modulates in the gut?
modulation of action of other agents
- PGE2, EP3 receptors.
- It negatively regulates the behaviour of the parietal cells + causes gastro protection
- Increases:
• Mucus secretion
• Blood flow
• Bicarbonate secretion, therefore there is neutralisation of Ach
• Gastrin mediated acid secretion in the gut
What is asprin?
- Archetypal NSAID (ASA)
What are NSAIDs (Non Steroidal Anti Inflammatory Drugs)
- Analgesic (pain prevention)
- Anti Pyretic (lowering raised temperature, fever)
- Anti Inflammatory (decreased immune response)
What are NSAIDs used to treat
- Low grade pain (chronic inflammation like arthritis)
- Bone pain (cancer metastases)
- Fever (associated with infections)
- Inflammation (fall in symptoms: oedema, redness, itch)
- Responses are dependent on inhibitory profiles, on different COXs.
What are the pharmacological mechanisms of NSAIDs
- The main therapeutic action, is by inhibition of COX.
1. Converts AA –> PG + TXs.
2. COX 1 (constitutively active, platelets)
3. COX 2 (inducible enzyme e.g. by IL-1B & TNFa)
4. Inhibition of COX-2 reduces PG/TXs inflammatory agents - Asprin acts irreversibly on COX
- Others can act reversibly & this is significant in its use as a prophylactic in cardiovascular disease
- Older generation NSAIDs, inhibit both COX-1 and COX-2
- Newer COX-2 selective agents could act as “super asprins” + paracetamol is a special case.
What are the pharmacological mechanisms of NSAIDs - what is the action of COX (which NSAIDs will inhibit)
- Converts AA –> PG + TXs.
- COX 1 (constitutively active, platelets)
- COX 2 (inducible enzyme e.g. by IL-1B & TNFa)
- Inhibition of COX-2 reduces PG/TXs inflammatory agents
Paracetamol is not an NSAID: what is paracetamol?
- Paracetamol is an analgesic that does not have anti-inflammatory effects
- Little inhibition of COX 1 / COX 2 in peripheral tissue
- Weakly inhibits COX 3 in the CNS - this does not explain its effects though.
- Might modulate serotonergic neurotransmission
- Inhibits COX mediated generation of hydroxypeptides from AA metabolis
- Hydroxypeptides, stimulate COX activity
Describe Antipyretic Action
- There are bacterial endotoxins that are produced during infections stimulate macrophages, to release Interleukin-1 (IL1)
Describe the action of IL-1B
- Acts on the hypothalamus, to cause PGE2 release
• Via COX2 - Increase in PGE2 depresses temperature sensitive neurones
- PGE2 elevates set point temperature which leads to the onset of a fever
- NSAIDs will block PGE2 production, which means that set point is lowered back to normal value + fever dissipates
- But NSAIDs will have no effect on normal body temperature
What do NSAIDs do to PGE2 production
- NSAIDs block PGE2 production = fever dissipation
- This means set point lowered to normal value
Analgesic action of NSAIDs
- Prostaglandins sensitise + stimulate the nociceptors
- Oedema is produced by inflammation + also directly activates nociceptive nerve fibres
- PGs interact synergistically with other pain producing substances
• Kinins
• 5HT
• Histamine - To produce hyperalgesia, which is increased sensitivity to pain relief
- Useful for pain that is associated with the production of inflammatory agents, like PGs/TXs:
• Arthritis, toothache, headache
• This is because NSAIDs inhibit PGs mediated vasodilatation
○ COX1, COX2, + COX2 inhibition in CNS
What happens when there is blockade of PG production?
- Breakage of this cycle
Leads to pain relief
Give examples of inflammatory agents
- PGs
- TXs
Anti-inflammatory action
- PGE2 + PGI2 have powerful acute inflammatory effects - Explain how
- Arteriolar dilatation, so increased blood flow
- Increased permeability in post capillary venules
- Both of these processes increase the influx of inflammatory mediators, into interstitial space
- Inhibition of their formation, reduces redness and swelling
Why do NSAIDs only provide symptomatic relief
- NSAIDs do not cure the underlying cause of inflammation - they help; but do not cure arthritis
- Fall in COX2 generated PGs - the effects develop gradually
Describe systems pharmacology of NSAIDS : Action on the Cardiovascular System
- TXA2- major role in vascular haemostasis - platelet aggregation, vasoconstriction
- NSAIDs decrease TXA2 - COX 1 product levels, and so increase bleeding time
• This could be problematic in surgery or childbirth - Where platelet aggregation is increased in disease, aspirin has a role in prophylactic treatment.
Describe how thrombo resistance is conferred by endothelial mediators: step 1
- Prevention of platelet aggregation in the vessel lumen
Describe how thrombo resistance is conferred by endothelial mediators: step 2
- When there is increased platelet aggregation, there is a fall in blood loss because of haemostasis
- Damaged endothelium will cause an increase in collagen and also Von Willebrand Factor (vWF)
- Inappropriate platelet aggregation will lead to thrombus + ischaemia heart disease
Why is aspirin beneficial in cardiovascular disorders - Inducible COX-2
- Endothelial cells produce PGI2 and COX
- Anti aggregator vasodilator
Why is aspirin beneficial in cardiovascular disorders - Constitutively active COX-1
- Platelet produces COX enzyme
- Which then makes TXA2
- This is a pro aggregatory vasoconstrictor
Why is asprin beneficial in cardiovascular disease - Inducible COX-2
- Anti- aggregatory vasodilator
- Plus low doses of aspirin
- Endothelial cell cannot produce PGI2 because COX inhibited.
Why is asprin beneficial in cardiovascular disease - Constitutively active COX-1
- Pro aggregator vasoconstrictor
- TXA2 cannot be produced because COX inhibited
Why is aspirin beneficial in cardiovascular disorders, over time [Inducible COX-2]
- New protein synthesis
- New COX, recovery
Why is aspirin beneficial in cardiovascular disorders, over time [Constitutively active COX-155]
- No protein synthesis in platelets - no new COX, no recovery
- Platelets cannot synthesise more COX
Skeletal action of PGs
- PGs with acute inflammatory effects contribute to swelling and pain in arthritis - joint pains
• Arteriolar dilatation
• Increased microvascular permeability
• Hyperalgesia - increased sensitivity to pain - NSAIDs thus diminish these effects but do not treat the cause
GI tract action of PGs
- PGs (PGE2/PGI2) important in protecting the gastric mucosa.
- Stimulate mucus secretion
- Inhibit gastric acid secretion
- NSAIDs decrease these cytoprotective mechanisms - bleeding and ulceration can result
- Gastric side effects are the most common adverse reactions to older NSAIDs
- COX 2 selective inhibitors might be gastric friendly - as it is suggested that COX 1 is expressed in the gut
- NSAIDs = acidic
List the effects of NSAIDs on the GI tract
- Decreased: mucus secretion, HCO3-
- Increased: acid secretion, LT production, blood loss
- Interefere with tissue healing (COX-2 inhibition)
- Nausea, dyspepsia, GI contraction (COX-1 inhibition)
Give examples of some COX2 selective agents
- Celecoxib
- Valdecoxib
- Etoricoxib [most selective COX 2 inhibitors]
- Rofecoxib
• These are withdrawn due to CV effects - not suitable for RA / osteoarthritis
• Use melaxicam, etodolac instead - COX-2 + NSAID = ulcer
What causes ulcers
- COX 2 + NSAID
Describe the action of Diclofenac (NSAID)
- Selective for COX2
- Inhibits COX 1 in GIT –> ulcers
- Less effective analgesics will have less inhibition of COX 3 in brain + spinal cord
CNS actions of NSAIDs
- NSAIDs inhibit pyrexia - therapeutic use
- In overdose, NSAIDs produce paradoxial hyperpyrexia, stupor + coma
• Increase in metabolism + metabolic acid production - Risk of Reyes syndrome (brain and liver damage), when used in children with influenza / chicken pox
What is the mechanism of Reyes syndrome
- This is why Aspirin is contraindicated in children. And Acetaminophen should be used instead
- Can alkalinize urine to help excretion of aspirin
Describe features of the genital tract involving PGs
- PGs cause pain + smooth muscle spasm during menstruation, NSAIDs are used as a treatment
• Mefanamic acid reduces blood loss
• NSAIDs might be useful in primary dysmenorrhoea - PGs (PGE2 + PGF2a) - important in uterine contractions in childbirth, thus NSAIDs delay contractions
- Lots of NSAIDs increase post partum blood loss, because TXA2 production prevented
- NSAIDs delay + retard labour
Describe the characteristics of the kidney and how it works
- Vasodilator PGs - (E2/I2) regulation of renal blood flow
- NSAIDs thus reduce renal blood flow
- Chronic renal injury might result.
- Effectiveness of some antihypertensive drugs is reduced by concurrent treatment with NSAIDs
- Inhibition of COX2, decrease in sodium excretion and increased intravascular volume
- Average blood pressure rise = 3/2 mmHg but varies
- Low dose aspirin does not seem to interfere with antihypertensive therapy but regular use should be avoided
Respiratory effects of PGs
- PGs (PGD2, PGF2a) have both constrictor + dilatator effects on airway smooth muscle - but NSAIDs have no effect on normal airway tone
- But NSAIDs must be avoided or used with caution in asthma
• Ca 20% asthma patients wheeze when given asprin, or other NSAIDs because they are hypersensitive to these drugs - @ toxic doses, aspirin initially stimulates respiration
• Actions of respiratory centre & uncoupling of oxidative phosphorylation - medulla stimulation
• Respiratory alkalosis caused by hyperventilation (Co2 ==> washout from lungs )
What are the other indications of NSAIDs
- Helps to achieve closure of patent ductus arteriosus in neonate
- If patency is inappropriately maintained by PGE2, PGI2 production (indomethacin, ibuprofen)
• Low birth weight infants
• Treatment is individualised
• May close by age 1 - Fast breathing / shortness of breath
- Sweating while feeding
- Tiring very easily
- Surgical closure
- Do not give NSAIDs by 3rd trimester to avoid premature closure of ductus
Give the other indications of NSAIDs
- Decrease colonic polyps & prevents colon cancer
- May decrease Alzheimers disease risk
- Post operative pain releif
- Renal colic - upper part of abdominal pain/groin usually caused by kidney stones
Aims of treatment of ulcerative colitis - Ø Ulcerative colitis = inflammation of bowel
- Reduce symptoms, known as inducing remission (a period without symptoms)
- Maintain remission
- First line treatment options:
Ø Aminosalicylates
Ø Sulfasalazine
Ø Mesalazine - Decreased inflammation for mild or moderate ulcerative colitis
- Short-term treatment of flareups
- Useful in the long term to maintain remission
What is the mechanism of action of sulfasalazine?
- Metabolised to 5-aminosalicylic acid (5-ASA) & sulfapyridine
- Reduces the synthesis of eicosanoids by blocking the activity of cyclooxygenase and lipoxygenase
- Cyclooxygenase and lipoxygenase activities are high in ulcerative colitis
What are the side effects sulfasalazine?
- Indigestion, feeling or being sick, abdominal pain, diarrhoea
- Dizziness, headache, difficultly sleeping, tinnitus
- Coughing: itchy rash, may affect your taste and cause sore mouth
What are the anti-inflammatory agents for gout
- Gout (a type of arthritis) accumulation of uric acid crystals in joints
- Painful inflammation caused by buildup of uric acid in the joints
- Uric acid (from purines) is in the blood & is harmless at low levels
- Uric acid prevents damage to blood vessel linings
- Passed out with the urine and faeces
- High level of uric acid in the blood (hyperuricemia) cause tiny grit-like crystals to collect in the joints which irritate the joint tissues, causing inflammation, and pain
Examples of anti-gout drugs
Ø Naprozen, Diclofenac, and Indomethacin
What is the mode of action of naproxen
- Inhibits COX1/COX2 levels which lowers PG levels - targets mediators engaged at the onset of inflammation
- Exhibits analgesic, anti inflammatory and antipyretic activity
- Inhibits platelet aggregation (inhibits platelet TXA2)
What are the side effects of naproxen
- Dizziness, nausea, indigestion, blurred vision, diarrhoea, abnormal liver function, water retention, ringing in the ears, hives
- Relatively risk neutral for CV events (heart attacks are rare)
Corticosteriod characteristics
- Can either be 1. Glucocorticoids (cortisol) 2. Mineralocorticoids (aldesterone)
- Both are synthesised, and released from the adrenal cortex - they are often termed the “salt + sugar” hormones
Glucocorticoid characteristics
- “sugar” hormone - carbohydrates + protein metabolism
- Potent anti inflammatory / immunosuppressant
Mineralocorticoids characteristics
- “salt” hormone - controls H20 and electrolyte in the kidney
What are the effects of glucocorticoids?
- Metabolic actions
- Breakdown of protein + fats (muscle wasting etc. )
- Decreased glucose usage + increased gluconegenesis
- Tendency to hyperglycaemia + increased glycogen storage
What are the effects of glucocorticoids?
- Metabolic actions
- Breakdown of protein + fats (muscle wasting etc. )
- Decreased glucose usage + increased gluconegenesis
- Tendency to hyperglycaemia + increased glycogen storage
What are the effects of glucocorticoids?
- Hormonal regulation
- Negative feedback on both the hypothalamus and pituitary gland
What are the effects of glucocorticoids?
- Cardiovascular system
- Decrease in both microvascular permeability + vasodilation
What are the effects of glucocorticoids?
- CNS
- Mood changes
- Linked with changes in memory / stress
Describe the anti- inflammatory effects of glucocorticoids
- Decreased microvascular fluid exudation
(- Reduces the influx of cells to areas of inflammation) - Decreased inflammatory mediators + cytokines
(- Decreased expression of COX-2
- Reduced levels of eicosanoids
- Decreased levels of cytokines + complement levels ) - Decreased function of inflammatory effector cells
- Inhibition of cell migration + mediator release
- Reduced clonal expansion of T and B cells
- Reduction in chronic inflammatory events
- NB healing and repair inhibited
(- Inhibition of cell migration + mediator release
- Reduced clonal expansion of T and B cells
- Reduction in chronic inflammatory events
- NB healing and repair inhibited)
What are the cellular mechanisms of glucocorticoids?
- Glucocorticoid enters the cell membrane
- Glucocorticoid binds to receptor (GCR) + dissociates HSP
- Glucocorticoid / GCR complex translocated to nucleus
- Expression of genes can be both increased or decreased
How can glucocorticoids switch gene expression on, or off? (1 via Interaction of steroid receptor with promoter regions)
- These gene promoters have: glucocorticoid response elements (GREs)
- Occupancy @ GREs will turn on or off certain genes
- This leads to increased expression of anti inflammatory proteins
○ Increased lipocortin which will decreased arachidonic acid and decreased eicosanoids - Decreased expression of pro-inflammatory proteins
- Decreased cytokine production