Oral administration
In a toxicity test involving oral administration of the drug/compound of interest, several methods can be considered mainly the oral gavaging and the dietary method
Gavaging is the process of force feeding whereby a tube is inserted into the mouth and down the oesophagus of the rat and the substance is subsequently emptied into the stomach via the syringe connected to the gavage tube.
Gavage VS Dietary method
The dietary method can be used if compound is suitable for mixing with the diet and that is stable under storage conditions similar to the diet. The compound must also be palatable to the animal.There are pros and cons to the dietary method. The advantage include beeing less laborious as compared to the need to gavage. The disadvantages include the exact concentration of compound for test which is mixed with food is hard to determine rather it is based on predicted food consumption and body weight. With the gavage method of dosing, a more precise amount of test compound can be delivered. However, there is a risk of punturing the oesophagus or even the lung if mishandled.
Gavage Techniques
1. Measure the distance from the tip of the nose to the last rib. This is the length of the needle that should be used. A curved needle is easiest to use and least likely to induce trauma
2. Fill syringe with appropriate amount of article to be dosed.
3. Restrain rat as mentioned in previous post
4. Place tip of the needle in rat's mouse
5. Slide ttip down back of the mouth, moving tip forward in one smooth motion
6. Needle should slide down the oesophagus easily. Resistance felt indicates that needle is not in place
7. Once everything is in place, administer the article
Gavaging is the process of force feeding whereby a tube is inserted into the mouth and down the oesophagus of the rat and the substance is subsequently emptied into the stomach via the syringe connected to the gavage tube.
Gavage VS Dietary method
The dietary method can be used if compound is suitable for mixing with the diet and that is stable under storage conditions similar to the diet. The compound must also be palatable to the animal.There are pros and cons to the dietary method. The advantage include beeing less laborious as compared to the need to gavage. The disadvantages include the exact concentration of compound for test which is mixed with food is hard to determine rather it is based on predicted food consumption and body weight. With the gavage method of dosing, a more precise amount of test compound can be delivered. However, there is a risk of punturing the oesophagus or even the lung if mishandled.
Gavage Techniques
1. Measure the distance from the tip of the nose to the last rib. This is the length of the needle that should be used. A curved needle is easiest to use and least likely to induce trauma
2. Fill syringe with appropriate amount of article to be dosed.
3. Restrain rat as mentioned in previous post
4. Place tip of the needle in rat's mouse
5. Slide ttip down back of the mouth, moving tip forward in one smooth motion
6. Needle should slide down the oesophagus easily. Resistance felt indicates that needle is not in place
7. Once everything is in place, administer the article
Fig 1: Gavaging of rat with tube
Fig 2: Measuring the tip and the anatomy of the rat
Fig 3: Gavage needles/tubes
5 comments:
hi raymon,
can i know what is the more preferred method of oral administration of drug?
and for the gavaging method,
isn't there a chance of choking the animal? and with the struggling of the animal, will the gavaging method be harder to perform??
(:
LIM JIA HUI (JOEY)
tg01 0703605f group 2
Hi Raymon,
Will the rat struggle if they are forced to put a tube into their mouth? Do you have to inject anesthetic into the mouse first before going through gavaging method?
Thanks
Lok Pui
hi raymon!
may i know what's the substance that you administer into the rat?
thanks!
stella
@ jia hui(joey): i have did a search and no books indicate which is the more preferred method however for accuracy purposes in a toxicity test i think the gavage tube is recommended as the exact concentration furthermore it potentially increases the bioavailability of the drug that might be loss possibly through the process of feeding(not gavaging) and also for the powdered form to be mixed with the regular diet, the homogenity is hard to determine.
with regards to the question on choking,the rats do struggle alot initially when they are handled because they are not accustom to human handling but after they get used to the routine they struggle less, the rats do choke and choking can be a sign indicating that the test material is poured into the lungs instead of the stomach so to prevent this from happening always restrain the rat firmly and maintain the animal in an upright (vertical) position and pass the gavage needle through the side of the mouth. Following the roof of the mouth, advance the needle into the esophagus and toward the stomach. If resistence is encountered you may be attempting to enter the trachea and you should alter your needle position.
if you are encountering difficulty in gavging, you can request for someone to hold the rat legs and tails to minimise the struggling
@lok phui: the struggling part is as mentioned in the reply to joey. Anesthetic is not required
@stella: for my experiment i gavage water to the control group and tea,herb extract to the experimental group
hi raymon,
can i know that is it the gavage needles is attached to the syringe or not when you transfer the drug solution into the syringe?
michi loh
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