Test 197  (Pharmacology)

1. Ethylene oxide:

a. can achieve sterilization at a temperature of 55⁰C

b. can be used to sterilize instruments that can not 
    withstand autoclaving

c. acts quicker than heat sterilization

d. is an efficient way of sterilizing plastic instrument

e. is toxic to the skin

 
Answera.T   b.T  c.F   d.F  e.T
Ethylene oxide is used for chemical sterilization. It is
a gas at room temperature. It can achieve sterilization at 55 degrees C in a humid atmosphere but the time
is relatively lengthy. It can used to sterilize delicate 
instruments that can not withstand autoclaving. When used to sterilize materials such as rubber or plastic, the gas is absorbed by the materials which should not be used for a few days. The chemical is toxic to skin. 

2. Hyalurodinase:

a. breaks down collagen

b. increases the permeability of the blood vessels

c. helps the spread of local anaesthesia 

d. does not affect tissue permeability beyond 48 hours

e. should be avoided in retrobulbar anaesthesia due to 
    the high risk of brainstem anaesthesia

 

Answera.T  b.F  c.T  d.T  e.F
Hyalurodinase breaks down collagen by digesting the hyaluronic acid. This helps to spread the local anaesthesia. The blood vessels and especially the capillaries are not affected by hyaluronidase as hyaluronic acid is not found in their walls. The permeability of tissue returns to normal after 48 hours due to formation of new hyaluronic acid. It is used in peribulbar and retrobulbar anaesthesia. There is a theoretical risk of increased brainstem anaesthesia when hyaluronidase is used but this complication is rare.

 
 

3. The following are true about adrenaline:
 

a. it decreases the metabolism of local anaesthetic

b. when combined with local anaesthetics gives a solution 
    with acidic pH

c. when combined with local anaesthetic increases the 
    pain of injection 

d. it should be avoided in peribulbar injection due to 
    the risk of central retinal artery occlusion

e. its total dose should not exceed 500mg in adult

 
Answer
a.T   b.T  c.T  d.F  e.T
Adrenaline when combined with local anaesthetics 
reduces blood flow and the metabolism of the local 
anaesthetic. The effect of anaesthesia is prolonged. 
An acidic pH occurs when adrenaline is combined
with local anaesthetic and this accounts for the increase in pain during injection. Sodium bicarbonate can be used to increase the pH of this solution and reduce the pain of injection. The use of adrenaline should be avoided
in digits and appendages. Central retinal artery occlusion is uncommon with the concentration of adrenaline used in peribulbar anaesthesia. 

 

. 4. Detergents:

a. with antiseptic properties are made up of 
    cationic agents

b. are combined with iodine to prepare the eyes for 
    intraocular operation

c. are more effective against Gram positive than Gram 
    negative bacteria

d. can cause corneal endothelium damage if allowed to 
    enter the anterior chamber

e. are used pre-operatively as surgical scrub

Answer
a.T  b.F  c.T  d.T  e.T
All detergents with antiseptic properties are cationic 
agents. They are generally more effective against Gram positive than Gram negative bacteria. Detergents can 
be combined with iodine as surgical scrub but the 
combination should not be used to prepare the eye for intraocular surgery due to the toxicity to corneal epithelium (de-epithelization). Contamination by detergent residue inside reusable cannulas can be toxic to the endothelium

5. Alcohol:

a. causes protein coagulation

b. of 70% concentration can be used as an antiseptic

c. causes de-epithelization when applied to the cornea

d. can be injected retrobulbarly to treat painful blind eye

e. found in Medi-swab is isopropyl alcohol (isopropanol)

 
Answer
a.T   b.T  c.T  d.T  e.T

 

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