Flashcards in Pharmacology Deck (43):
Where are alpha 1 receptors found and what is their action?
Found on vascular smooth muscle --> vasoconstriction
Found on urinary sphincter, iris, liver and kidney
Where are alpha 2 receptors found and what is their action?
Pancreatic islets --> decreased insulin secretion
Where are beta 1 receptors found and what is their action?
Located on heart --> increased HR and AV node conduction
JGA cells --> increase renin --> increase BP
Where are beta 2 receptors found and what is their action?
Lungs - bronchodilation
Vascular smooth muscles and arteries - vasodilation
Gi tract - decreased Gi motility
Pancreas - increase insulin secretion
Uterus - inhibition of labour
Where are beta 3 receptors found and what is their action?
Adipose tissue to increase lipolysis
Urinary sphincter- cause prevention of urination
What is the rawling thompson classification?
Classification of an adverse drug reaction
What is a type A drug reaction?
Predictable, dose dependent and common, usually an extension of a primary effect e.g. hypotension and antihypertensive
What is a type B drug reaction?
Not predictable and not dose dependent. Often involves allergic reaction e.g. penicillin allergy
What is a type C drug reaction?
Regular use of a medication overtime e.g. steroids and osteoporosis
What is a type D drug reaction?
Example malignancies after immunosuppression
What is a type E drug reaction?
End of treatment
Occur after abrupt drug withdrawal
How do you report an adverse drug reaction?
Inform to MHRA - GMC stimulation
Report using yellow card scheme - early warning system for previously unrecognised reactions
What informations should you include on a yellow card?
What the drug is, what the reaction is, patient details and reporter details
What is a black triangle medicine?
Conditional approval of medication which is undergoing additional monitoring
What are the patient risk factors of an ADR?
Gender, age, neonates, genetic predisposition, allergies, polypharmacy, hepatic or renal failure, adherence problems
What are the drug risk factors for an ADR?
1. Low therapeutic index
2. Steep dose/response curve
3. Commonly causes ADR's
Name 5 causes of ADR's?
1. Pharmaceutical variation
2. Receptor abnormality
3. Abnormal biological system unmasked by drug
4. Abnormalities in drug metabolism
5. Drug-drug interaction
In a patient with anaphylactic shock, what are the first 3 management steps?
1. Commence basic life support ABC
2. Adreneline IM 500mg
3. High flow oxygen and IV fluids
How does adrenaline treat anaphylaxis?
Alpha 1 - vasoconstriction --> increase Bp and coronary perfusion
Beta 1 - positive ionotropic and chronotropic effects
Beta 2 - decrease oedema and bronchodilates
Increases cAMP which reduces release of inflammatory mediators
Name 4 of the clinical criteria for an allergy to a drug?
1. Doesn't correlate with pharmaceutical properties of drug
2. No linear relation with dose
3. Reaction similar to those produced by other allergens
4. Induction period of primary exposure
5. Disapearance on cessation
6. Re-apears on exposure
7. Occurs in a minority of patients on the drug
What is type 1 hypersensitivity?
Allergen identified --> IgE binds --> Mast cells activated --> granules released of histamine and cytokines
Cytokines induce a Th2 response
What is type 2 hypersensitivity?
Drug combines with protein, body treats it as foreign and forms antibodies IgG and IgM --> complement activation --> damaged to cells
What is type 3 hypersensitivity?
Antigen and antibody form large complexes which activate the complement
What is type 4 hypersensitivity?
Eg contact dermatitis
Name 5 barriers to concordance?
1. capacity and resources - e.g. cost of drugs
2. Concerns about mediation - worries about side effects
3. Necessity beliefs about medication - feel there is no need for the treatment
4. Practical barriers to adherence
5. specific beliefs about medication
How do you treat opioid induced respiratory depression?
ABC and IV Naloxone
How do opioids work?
Inhibit release of pain transmitters at spinal cord and midbrain, modulate pain perception in the higher centres (euphoria) changes the emotional perception of pain
What happens in phase 1 of drug metabolism?
Transformation of drug to polar metabolite catalysed by cytochrome P450
What happens in phase 2 of drug metabolism?
Conjugation step - involves formation of covalent bond between drug.phase 1 metabolite and endogenous substrate so they are less active and more water soluble
Name 4 things that drug absorption can be affected by?
1. Drug structure eg lipid soluble? pH?
2. Drug formulation e.g. capsule or coating
3. Gastric emptying- metabolism slowed down by food
4. First pass metabolism
Give an example of a drug which is a weak acid?
Give an example of a drug which is a weak base?
How do statins reduce lipids?
Block the rate limiting step in the cholesterol pathway - HMG- CoA reductase
What is first order kinetics?
Change in concentration at any time is proportional to concentration
What is zero order kinetics?
Change is concentration per time is a fixed amount of drug per time, independent of concentration
What is the definition of clearance?
Volume of blood plasma cleared of drug per unit of time
What is the definition of distribution?
Rate and extent of movement of drugs into and out of tissues from the blood
What is the definition of bioavailaibilty?
The fraction of the drug which reaches your circulation un-altered
What is the definition of half-life?
The time taken for the concentration to reduce by one half
What is the definition of efficacy?
How well a ligand activates a receptor
What is the definition of affinity?
How well a ligand binds to a receptor. Define the amount of drug required to produce 50% of the maximum, normally expressed as reciprocal unit
What is the definition of intrinsic ability?
Refers to the ability of a drug-receptor complex to produce a maximum functional response