LEC 6 - Nonopioid Analgesics Flashcards
What are the four signs of inflammation?
Erythema + Edema + Tenderness + Pain
What are the three phases of inflammation?
Acute inflammation
Immune response
Chronic inflammation
What are the five mediators of acute inflammation?
Histamine
Serotonin
Bradykinin
Prostaglandin
Leukotrine
What are the four effects of the acute inflammatory mediators?
Vasodilation
Vascular permeability
Chemotaxis
Pain
Effects: Histamine
Vasodilation ++
Vascular Permeability +++
Effects: Serotonin
Vasodilation +/-
Vascular permeability +
Effects: Bradykinin
Vasodilation +++
Vascular permeability +
Pain +++
Effects Prostaglandin
Vasodilation +++
Vascular Permeabiltiy +
Chemotaxis +++
Pain +
Effects: Leukotrines
Vascular permeability +++
Chemotaxis +++
What is the precursor to LT’s + PG’s?
Arachodonic Acid
What makes LTs?
Lipoxygenases
What makes prostaglandins?
COX 1/2
What is the structure of prostaglandins?
Oxygenation products of polyunsaturated long chain FA’s
How does arachodonic acid leave the membrane?
Via phospholipase A2
Characteristic: COX-1
Constitutively expressed
Housekeeping functions
Widely distributed
Characteristics: COX-2
Inducible
Depends on stimulus
Immediate early response gene
What are the main functions of the products made by COX-2?
Stimulate growth factors
Tumor promoters
Cytokines
What is COX-2 mainly responsible for?
Prostacylcin in endothelial cells
Describe the mechanism by which Asprin Asthma occurs?
NSAID blocks COX enxymes = decrease in PG’s
Increase A. Acid that gets shuttled to Lipoxygenase path
Increased production of Leukotrines
= Increase broncoconstirction + congestion + mucous plugging
Mechanism: Asprin/ASA/Acetylsalicyclic acid
Nonselective, irreversible inhibitor of COX-1/2
Asprin - Effects
Analgesic
Antipyretic
Anti-inflammatory
Platelet
Describe: Asprin’s analgesic effects
Low intensity pain
Pain from integumental structures
Due to peripherial + CNS effects
Prevents sensitization of pain receptros to stimuli
How does asprin act locally?
Hypothalmic area to reduce fevers
When does asprin not work?
As an analgesic in non-inflammed painful conditions
When is aspirin successful at lowering temperature?
Febrile patients
Fever due to inflammation + infection + tissue damage
By what mechanism does aspirin reduce fever?
Resetting the thermostat to normal body temp
Therefore problem needs to be within the hypothalamus
Aspirin - Distribution
Throughout body tissues + ETC compartments
Crosses placenta
Slowly crosses BBB
Aspirin - Metabolism
Hydrolyzed = Plasma + Liver + Erythrocytes
Salicylic acid - Glucuronidated in liver
Aspirin - Elimination
Kidney
Aspirin - Half lives
Dog
Cat
Horse
8 hours - dog
38 hours - cat
30 min - horse
Aspirin - Protein Binding
Plasma protein - 50 ot 90%
Aspirin - Adverse Effects
GI upset
Paradoxical hyperpyrexia
Dehydration
Pulmonary edema in sheep
What happens in canines with chronic asprin use?
Canine chondrocytes are sensitive to COX-1 inhibition
Aggrevation of canine joint disease
How long before surgery must asprin be discontinuesd?
7 days
How does aspirin cause hyperpyrexia?
uncoupling of oxidative phosphorylation
How does asprin cause acid-base disturbances?
1- Alkalosis via stimulation of medullary respiratory center = hyperventilation
2 - Acidosis due to CNS depression
How does aspirin cause pulmonary edema in sheep?
Imbalance of vasodilatory PG’s + Vasocontrictive PG’s
Increased vascular permeability
Aspirin - Administration
Oral
Aspirin - Uses
Adjunct therapy for septic + endotoxic shock
Aspirin - Contraindicated treatment
OA
Colic
Aspirin - Drug interactions
Due to salicylate-mediated displacement of other drugs that compete for same albulmin binding site
Warfarin
Throxin T3
Penicillin
Thiopental
Bilirubin
Phenytonin
Naproxen
How do you treat aspirin toxicity?
Induce vomiting
Increase removal of drug - gastric lavage + activated charcoal
Increase urinary excretion - alkalinizing agent
IV fluids