Download SMU-DDE-Assignments-Scheme of Evaluation PROGRAM Bachelor

SMU-DDE-Assignments-Scheme of Evaluation
PROGRAM
SEMESTER
SUBJECT CODE &
NAME
BK ID
SESSION
MARKS
Q.No
1.
A
Bachelor/Diploma in Medical Imaging Technology
II
BMI 204– Basics of Pharmacology
B1950
WINTER 2015
30
Criteria
Marks
Total
Marks
Define pharmacology. Explain pharmacodynamic and pharmacokinetic principles.
(Unit 1;Section 1.2 & 1.5;Pg 2,17-19)
Pharmacology is the study of drugs and their effects on life processes. It
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is a fundamental science that has reached the forefront of modern
medicine by demonstrating success in treating disease and saving lives.
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The actions of the drug on the body are termed as
pharmacodynamics.
The effect of a drug present at the site of action is determined by
that drug’s binding with a receptor. However, at the molecular level,
drug binding is only the first among a complex set of events.
Types of drug – receptor interactions: Agonist drugs bind to and
activate the receptor in some fashion, which directly or indirectly
brings about the effect. Some receptors incorporate effector
machinery in the same molecule, so that drug binding brings about
the effect directly, e.g., opening of an ion channel or activation of
enzyme activity. Other receptors are linked through one or more
intervening coupling molecules to a separate effector molecule.
"Agonists" that inhibit their binding molecules and partial agonists:
Some drugs mimic agonist drugs by inhibiting the molecules
responsible for terminating the action of an endogenous agonist. For
example, acetylcholinesterase inhibitors, by slowing the destruction
of endogenous acetylcholine, cause cholinomimetic effects that
closely resemble the actions of cholinoceptor agonist molecules.
Duration of drug action: Termination of drug action at the receptor
level results from one of several processes. In some cases, the effect
lasts only as long as the drug occupies the receptor, so that
dissociation of drug from the receptor automatically terminates the
effect. In many cases, however, the action may persist after the drug
has been dissociated.
Receptors and inert binding sites: To function as a receptor, an
endogenous molecule must first be selective in choosing ligands
(drug molecules) to bind; and second, it must change its function
upon binding in such a way that the function of the biologic system
(cell, tissue, etc) is altered.
4.5
SMU-DDE-Assignments-Scheme of Evaluation
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Pharmacokinetic processes govern the absorption, distribution, and
elimination of drugs and are of great practical importance in the
choice and administration of a particular drug for a particular
patient, e.g., one with impaired renal function.
In practical therapeutics, a drug should be able to reach its intended
site of action after administration by some convenient route. In
some cases, a chemical that is readily absorbed and distributed is
administered and then converted to the active drug by biologic
processes inside the body. Such a chemical is called a prodrug.
In only a few situations it is possible to directly apply a drug to its
target tissue E.g., Topical application of an anti-inflammatory agent
to inflamed skin or mucous membrane.
Most often, a drug is administered into a body compartment, like the
gut, and is moved to its site of action in another compartment, say
the brain.
This requires that the drug be absorbed into the blood from its site
of administration and distributed to its site of action, permeating
through various barriers that separate these compartments.
For an oral drug affecting the central nervous system, these barriers
include the tissues comprising the intestinal wall, the capillary wall
that perfuse the gut and the blood-brain barrier or the walls of
capillary that perfuse the brain.
Finally, after bringing about its effect, a drug should be eliminated
at a reasonable rate by metabolic inactivation, by excretion from the
body, or by a combination of these processes.
4.5
Discuss the classification, pharmacological actions, uses and adverse effects of cholinergic
agonists.
(Unit 2;Section 2.3;Pg 30-32)
Cholinergic agonists are also known as parasympathomimetics or
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cholinomimetics. These are the drugs that produce the action similar to
that of parasympathetic simulations. They basically act either by directly
interacting with cholinergic receptors (cholinergic agonists) or by
increasing availability of Ach at these sites (anticholinesterases).
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Classification
1. Choline esters: ACh, Methacholine, Carbochol, Bethanechol.
2.Natural alkaloids
a) Muscarinic: Muscarine, Pilocarpine, Arecholine.
b) Nicotinic: Nicotine, Lobeline, Dimethylphenylpiperazinium
(DMPP)
3. Synthetic alkaloids: Areclinidine, Oxotremorine.
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Pharmacological actions
Depending on which receptors Ach is binding to, peripheral actions can
be either muscarinic or nicotinic.
a) Cardiovascular system:
i) ACh hyperpolarizes SA nodal cells: ↓ rate of diastolic depolarization
therefore, ↓ rate of impulse generation. Therefore it causes bradycardia
or even cardiac arrest.
ii) At AV node and His-Purkinje fibres: ↑ refractory period and ↓
conduction which causes partial AV blockade leading to ↓ force of atrial
contraction thereby reducing ventricular contractility.
SMU-DDE-Assignments-Scheme of Evaluation
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b) Blood vessels: Decrease in blood pressure due to NO-mediated
vasodilatation.
c) Gastrointestinal tract: The G.I. tract is contracted. There is increased
tone, motility and peristalsis. The sphincters are relaxed, thus there is
rapid propulsion of food. Detrusor muscle is contracted.
d) Respiratory system: Bronchial muscle are contracted to produce
bronchospasm. This may cause apnea (temporary absence or cessation
of breathing). Hence, cholinergic drugs are contraindicated in asthmatic
condition.
e) Glands: Increase secretions from all glands.
f) Eye: Cholinergic drugs cause contraction of circular muscles of iris.
Hence, they produce miosis. It even contracts ciliary muscles which
causes spasm of accommodation and reduction in intraoccular tension.
g) Skeletal muscles: Parasympathomimetics contract the skeletal
muscles through nicotinic effect. Anticholinesterases in particular
increase the strength of muscle contraction and may produce fibrillation
and fasciculations. Some Anticholinesterases are useful in myasthenia
gravis.
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Uses:
 Bethanechol is used in post-operative or post-partum urinary
retention, neurogenic bladder atony, congenital megacolon,
gastroesophageal reflux.
 Carbachol is rarely used therapeutically except in the eye as a
miotic agent to treat glaucoma to decrease the intraocular pressure.
 Pilocarpine is used only in the eyes as 0.5-4% drops in open angle
glaucoma.
 Pilocarpine and cevimeline, a newer muscarinic receptor agonist
increases salivary secretions. They are used to treat Sjogren’s
syndrome (a systemic autoimmune disease in which immune cells
attack and destroy the exocrine glands that produce tears and
saliva.)
 Methacholine is occasionally used to diagnose bronchial
hypersensitivity and asthmatic conditions.
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Adverse effects:
Belching, colic, involuntary urination, defecation, flushing, sweating,
fall in blood pressure, bronchospasm.
Discuss the drugs used for peptic ulcers.
(Unit 5;Section 5.2;Pg 85-89)
SMU-DDE-Assignments-Scheme of Evaluation
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2+2+2+2+2
Explanation of the following
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1. Reduction of gastric acid secretion
a) H2-antihistamines: Cimetidine,
Roxatidine, Loxatidine
Ranitidine,
b) Proton pump inhibitors: Omeprazole,
Pantoprazole, Rabeprazole, Esomeprazole
Famotidine,
Lansoprazole,
c) Anticholinergics: Pirenzepine, Propantheline, Oxyphenonium
d) Prostaglandin analogues: Misoprostol, Enprostil, Rioprostil
2. Neutralizing of gastric acid (Antacids)
a) Systemic: Sodium bicarbonate, Sodium Citrate
b) Non-systemic: Magnesium hydroxide, Magnesium trisilicate,
Aluminium hydroxide gel, Magaldrate, Calcium carbonate
3. Ulcer protectives: Sucralfate, Colloidal bismuth subcitrate (CBS)
4. Ulcer healing drugs: Carbonoxolone sodium
5. Anti-H. pylori drugs: Amoxicillin, Clarithromycin, Metronidazole,
Tinidazole, Tetracycline
*A-Answer
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