P2

Question 1

Dimorphine

Answer 1

An analgesic

Mu-opioid agonist

MoA: Heroin, targets 4 endogenous neurotransmitters (beta-endorphin, dynorphin, leu-enkephalin, and met-enkephalin). Heroin reduces (and sometimes stops) production of the endogenous opioids. Endorphins are regularly released in the brain and nerves, attenuating pain.

Question 2

Atenolol

Propranolol

Answer 2

Beta-adrenergic antagonist

MoA: Atenolol has similar properties to propranolol, but does not have a negative inotropic effect. Higher doses of Atenolol also competitively block beta(2)-adrenergic responses in the bronchial and vascular smooth muscles.

SE:

• Bronchoconstriction in asthma
• Heart block/failure in coronary disease
• Decreased warning in hypoglycaemia
• Fatigue/lethargy
• Peripheral vasoconstriction (cold extremities)
• Metabolic (decreased HDL, increased TGs, increased risk of new onset DM)

Question 3

Bendroflumethiazide

Answer 3

Sodium chloride cotransporter inhibitor

Thiazide diuretic

MoA:
o It inhibits the Na-Cl cotransporter, blocking active chloride reabsorption in the early distal tubule. This results in an increase in the excretion of sodium, chloride, and water.
o It inhibits sodium ion transport across the renal tubular epithelium through binding to the thiazide sensitive sodium-chloride transporter. This results in an increase in potassium excretion via the sodium-potassium exchange mechanism.

Question 4

Amiodarone

Answer 4

Antianginal and antiarrhythmic agent.

Amiodarone is a Vaughan-Williams Class III antiarrhythmic agent.

MoA: Prolonging the myocardial cell-action potential (phase 3) duration and refractory period and it acts as a noncompetitive a- and b-adrenergic inhibitor.

Question 5

Norepinephrine

Answer 5

Norepinephrine is a precursor of epinephrine secreted by the adrenal medulla.

MoA: Norepinephrine is the principal transmitter of most postganglionic sympathetic fibres and of the diffuse projection system in the brain arising from the locus ceruleus.

Norepinephrine functions as a peripheral vasoconstrictor by acting on both alpha-1 and a-2 adrenergic receptors. It is also an inotropic stimulator of the heart and dilator of coronary arteries as a result of it’s activity at the beta-adrenergic receptors

Use: Only given in ICU as infusion for cardiovascular support

Question 6

Verapamil

Answer 6

Class IV anti-arrhythmia agent

MoA: Verapamil inhibits voltage-dependent calcium channels. In the heart it blocks the L-type calcium channels causing a reduction in ionotropy and chronotropy, reducing heart rate and blood pressure.

Use: Verapamil is still used (not commonly) but it can only be given via IV. Diltiazem more common as a non-dihydropyridine Calcium Channel Blocker, but this is not available via IV (although it is in the USA).