Test 210 (Pharmacology)

1. Latanoprost:

a. increases uveoscleral outflow

b. increases trabecular meshwork outflow

c. increases existing inflammation

d. causes iris hyperpigmentation by stimulating the 
    multiplication of melanocytes

e. causes pupillary dilatation

Answer
a. T   b.F   c.T   d.F   e.F
Latanoprost works by increasing uveoscleral outflow. It does not increase trabecular meshwork outflow nor reduce the aqueous production. It can increase existing ocular inflammation. It causes iris hyperpigmentation by increasing the production of melanin by existing melanocytes. It has no effect on pupil size.

2. Cocaine:

a. is a direct-acting sympathomimetic drug

b. causes pupil dilation in normal people

c. causes pupil constriction in Horner's syndrome

d. can be used to differentiate between preganglionic and 
    postganglionic Horner's syndrome 

e. does not affect accommodation

Answer
a.F   b.T   c.F   d.F   e.F
Cocaine is an indirect-acting sympathomimetic drug and inhibits the reuptake of cathecoamines. It causes pupil dilation and partial cycloplegia in normal people. In Horner's syndrome, the pupil does not react to cocaine due to deinnervation. It can not be used to differentiate between preganglionic and postganglionic Horner's syndrome.
 

3. The following side-effects are seen in b-antagonists: 

a. reduced tear production

b. decreased corneal sensation

c. myopic shift

d. impotence

e. poliosis

Answer
a.T   b.T  c.F   d.T   e.F
Reduced tear production and corneal sensation are known side-effects of beta blockers. Impotence can occur with systemic absorption.

4. Regarding steroid used to treat eye disease:

a. removal of corneal epithelium will increase the ocular 
    penetration of corticosteroid

b. acetate preparation then to come in suspension form

c. phosphate preparation has a better corneal penetration 
    than acetate preparation

d. subconjunctival injection of corticosteroid achieve a 
    better ocular penetration than topical instillation

e. chronic use can lead to eyelid retraction

Answer
a.T   b.T   c.F   d.T   e.F
The ideal steroid should be biphasic in polarity, because the cornea contains both hydrophobic and hydrophilic layers. Removal of the corneal epithelium reduces the hydrophobic properties and allows greater penetration by hydrophilic preparations ie. phosphate over the acetate preparation. 

Acetate preparation is hydrophobic whereas phosphate preparation is hydrophilic. Acetate preparation tends to come as suspension whereas phosphate 
preparation as solution form. In the intact cornea, the hydrophobic preparation ie. acetate has a better penetration.
Chronic use of steroid can cause weakness of levator muscle leading to ptosis.

5. The following are true about corticosteroids:

a. they are synthesized in the adrenal medulla

b. they are 21-carbon structures

c. ACTH is essential for the production of corticosteroids 
    from cholesterol

d. 17a-hydroxylation is present in most of the 
    anti-inflammatory steroids

e. they increase renal excretion of potassium 

Answer
a.F   b.T   c.T   d.T  e.T
Corticosteroids are synthesized in the adrenal cortex 
under the influence of ACTH. They are 21-carbon structures. 17 alpha hydroxylation is found in most 
anti-inflammatory steroids. They increase the renal absorption of sodium and renal excretion of potassium.

 

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