Dose-Response, Efficacy, Potency | Direct Parasympathomimetics | CCBs

Question 1

DR response types and their uses | Efficacy and Potency

Answer 1

DR response relationship is a plotted graph showing the dose/concentration of a drug and its response on the cell/receptor

It is a Pharmacodynamic measurement

We can determine pharmacodynamic relations like Efficacy, Potency, Affinity to receptor

They can be Hyperbolic curves or Sigmoid curves [log function of dose]

Efficacy - maximal effect or amount of effect a drug has to its receptor measured in % ??
Potency - amount of drug needed to produce a specific effect, compared with other drugs
Affinity - measured with Km or Emax/2, lower the Km higher is the drugs affinity to the receptor

Make graphs of 2 drugs and compare its efficacy, potency and affinity and explain

Question 2

Direct acting Parasympathomimetics

Answer 2

These drugs are non-selective, Acetylcholine receptor agonists. They can effect both Nicotinic and Muscarinic receptors however they tend to have effects specifically on Muscarinic receptors
Nicotinic receptor agonists are mainly Indirect Acetylcholine agonists and tend to involve both neuronal and muscular type

These agents directly bind to nAchR or mAchR, they are:
- Acetylcholine [endogenous]
- Methacholine [lung disease subtypes dx like bronchial asthma, or diseases causing bronchoconstriction]
- Bethanochol [treat non-obstructive decreased motility GI like postoperative Ileus or neurogenic Ileus, increase urination via detrusor muscle contraction and sphincter relaxation]
- Carbochol [Acute glaucoma treatment by pupillary constriction]
- Nicotine/Muscarine [plant alkaloids]
- Pilocarpine [plant alkaloids, treatment for Xerostomia in Sjogrens and glaucoma]

Main effects of these agonists are on: [think, REST and DIGEST]
- Eye
- Heart
- Glands [NOT sweat glands]
- Blood vessels
- Lungs
- GI
- Bladder

Question 3

Calcium channel blockers

Answer 3

2 types:
- Dihydropyridine derivatives [Amlodipine, Nifedipine]
- Non-Dihydropyridine derivatives [Verapamil, Diltiazem]

Main effect: Verapamil, Diltiazem
- Nodal Action potentials of SA and AV [L and T type calcium channels]
- Phase 0 and Phase 4, leading to slower subsequent AP generation and decrease in heart work
- Considered Rate Control drugs [not given in AV blocks or heart failure]

Main effect: Amlodipine, Nifedipine
- Vasodilation and decrease in TPR
- Decreased Afterload and decreased venous return
- Lowering of BP and workload of heart