7/28/2019 PCOL Chp 4-6 (Situational Analysis)

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Situational Analysis:

4.1 A patient with an acute attack of glaucoma is treated

with pilocarpine. The primary reason for its effectiveness

in this condition is its:

Answer:Ability to lower intraocular pressure.

- Pilocarpine can abort an acute attack of glaucoma,because it causes papillary constriction to lower

intraocular pressure. It binds mainly to muscarinic

receptors and can enter the brain. It is not effective ininhibiting secretions.

4.2A soldiers unit has come under attack with a nerve

agent. The symptoms exhibited are skeletal muscle

paralysis, profuse bronchial secretions, miosis,

bradycardia, and convulsions. The alarm indicates

exposure to an organophosphate. What is the correct

treatment?

Answer:Administer atropine and 2-PAM (pralidoxime)

- Organophosphates exert their effect by irreversiblybinding to acetylcholinesterase and, thus, can cause a

cholinergic crisis. Administration of atropine willblock the muscarinic sites; however, it will not

reactivate the enzyme, which will remain blocked for a

long period of time. Therefore, it is essential to also

administer 2-PAM as soon as possible to reactivate the

enzyme before aging occurs. Administering 2-PAM

alone will not protect the patient against the effects of

acetylcholine resulting from acetylcholinesterase

inhibition.

4.3 A patient is being diagnosed for myasthenia gravis

would be expected to have improved neuromuscular

function after being treated with:

Answer: Edrophonium- Edrophonium = is a short acting inhibitor of

acetylcholinesterase that is used to diagnose

myasthenia gravis. It is a quaternary compound and

does not enter the CNS.

- Donepezil = is used in the treatment of Alzheimersdisease.

- Ecothiophate = has some activity in treating open-angle glaucoma.

- Neostigmine = is used in the treatment of myastheniagravis but is not employed in its diagnosis.

- Atropine = is a cholinergic antagonist and, thus, wouldhave the opposite effects.

4.4 The drug of choice for treating decreased salivation

accompanying head and neck irradiation is:

Choices: Physostigmine, Scopolamine, Carbachol,

Acetylcholine, or Pilocarpine.

Answer: Pilocarpine

- Pilocarpine has proven to be beneficial in thissituation. All the others except scopolamine are

cholinergic agonists. However their ability to

stimulate salivation is less than that of pilocarpine,

and their other effects are more troublesome.

5.1 A 75-year-old man who was a smoker is diagnosed

with chronic obstructive pulmonary disease and suffers

from occasional bronchospasm. Which of the following

would be effective in treating him? (Ipratropium aerosol,

Scopolamine patches, Mecamylamine, Oxygen)

Answer: Ipratropium aerosol

- This is a drug of choice, especially in patient whocannot tolerate an adrenergic agonist, which would

dilate the bronchioles.- Scopolamines main effect is atropinic, and is themost effective anti-motion sickness drug.

- Mecamylamine is a ganglionic blocker and completelyinappropriate in this situation.

- Oxygen would improve aeration but would not dilatethe bronchial musculature.

5.2 Which of the following may precipitate an attack of

open-angle glaucoma if instilled into the eye?

(Physostigmine, Atropine, Pilocarpine, Echothiophate)

Answer:Atropine

- The mydriatic effect of atropine can result in thenarrowing of the canal of Schlemm leading to anincrease in intraocular pressure. The other agents

would cause miosis.

5.3 The prolonged apnea sometimes seen in patients who

have undergone an operation in which succinylcholine was

employed as a muscle relaxant has been shown to be due

to: (urinary atony, Depressed levels of plasma

cholinesterase, A mutation in acetylcholinesterase, A

mutation in the nicotinic receptor at the neuromuscular

junction)

Answer: Depressedlevels of plasma cholinesterase

-

These patients have a genetic deficiency of thenonspecific plasma cholinesterase that is required for

the termination of succinylcholines action.

5.4 A 50-year-old male farm worker is brought to the

emergency room. He was found confused in the orchard

and since then has lost consciousness. His heart rate is 45,

and his blood pressure is 80/40 mmHg. He is sweating and

salivating profusely. Which of the following treatments is

indicated? (Physostigmine, Norepinephrine,

Trimethaphan, Atropine, Edrophonium)

Answer:Atropine

- The patient is exhibiting signs of cholinergicstimulation. Because he is a farmer, insecticidepoisoning is a likely diagnosis. Thus either

intravenous or intramuscular doses of atropine are

indicated to antagonize the muscarinic symptoms.

- Physostigmine and edrophonium are cholinesteraseinhibitors and would exacerbate the problem.

- Norepinephrine would not be effective in combatingthe cholinergic stimulation.

- Trimethaphan, being a ganglionic blocker, would alsoworsen the condition.

7/28/2019 PCOL Chp 4-6 (Situational Analysis)

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6.1 A 69-year-old man presents to the emergency

department with acute heart failure. You decide that this

patient requires immediate drug therapy to improve his

cardiac function. Which one of the following drugs would

be most beneficial? (Albuterol, Dobutamine, Epinephrine,

Norepinephrine, Phenylephrine)

Answer: Dobutamine

- Dobutamine increases cardiac output withoutsignificantly increasing heart rate a complicatingcondition in heart failure. Because epinephrine can

significantly increase heart rate, it is not usually

employed for acute heart failure. Both norepinephrine

and phenylephrine have significant a1-receptor-

stimulating properties. The subsequent increase in

blood pressure would worsen the heart failure.

Albuterol, a b2-selective-receptor agonist, would not

improve contractility of the heart significantly.

6.2 Remedies for nasal stuffiness often contain which one

of the following drugs? (Albuterol, Atropine, Epinephrine,

Norepinephrine, Phenyephrine)

Answer: Phenylephrine- Phenylephrine is an a-agonist that constricts the nasal

mucosa, thereby decreasing airway resistance,

- Norepinephrine and epinephrine also constrict themucosa but have much too short a duration of action.

- Albuterol is a b2-agonist and has no effect on mucosalvolume. Atropine, a muscarinic atagonist, only dries the

mucosa it does not decrease its volume.

6.3 Which one of the following drugs, when admin. IV, can

decrease blood flow to the skin, increase blood flow to the

skeletal muscle, and increase the force and rate of cardiac

contraction? (epinephrine, Isoproterenol, Norepinephrine,

Phenylephrine, Terbutaline)Answer: Epinephrine

- Exogenous epinephrine stimulates alpha and betareceptors equally well, leading to the constriction of

blood vessels in tissues such as skin and dilation of

other blood vessels in tissues such as skeletal muscle.

- Epinephrine also has positive chonotropic andinotropic effects in the heart. Exogenous

norepinephrine constricts blood vessels only and

causes a reflex bradycardia because of its strong alpha

adrenergic stimulating properties. Phenylephrine has

similar effects. Isoproterenol stimulates beta receptors

and would not cause vasoconstriction of cutaneousvessels.

6.4 The following circles represent papillary diameter in

one eye prior to and following the topical application of

Drug X:

Control Drug X

Which of the following is most likely to be Drug X?

(Physostigmine, Acetylcholine, Terbutaline, Phenyephrine,

Isoproterenol)

Answer: Phenylephrine

- Phenylephrine is the only drug in the list that causesmydriasis, because it stimulates a-receptors. Both

physostigmine and acetylcholine cause papillary

constriction. The b-blockers, terbutaline and

isoproterenol, do not influence papillary diameter.