P24: Digestive System

What are the classifications of drugs affecting the mouth and pharynx?

salivary stimulants (sialagogues), salivary inhibitors (antisialagogues)

What is an example of a sialagogue?

gentian

What is an example of an antisialagogue?

(parasympatholytic) atropine

Why are drugs affecting the oesophagus used?

to relax its tonus (spasmolytic),
to increase peristalsis,
to close the oesophageal groove

What is an example of drug used to relax the tonus of the oesophagus?

acepromazine

What are the classifications of drugs affecting the rumen, stomach and proventriculus?

carminatives and antispasmodics, emetics, antiemetics, antitympanics

What are examples of carminatives and antispasmodics?

turpentine oils, peppermint, atropine

What are examples of emetics?

apomorphine HCl, xylazine

What are examples of antiemetics?

chlorpromazine, acepromazine

What are classifications of drugs affecting the intestines?

purgatives and laxatives, antidiarrhoeal drugs, spasmolytics

What are examples of purgatives and laxatives?

liquid paraffin, magnesium sulphate, aloe, senna leaves

What are examples of antidiarrhoeal drugs?

activated charcoal, tanninum

What are examples of spasmolytics used for the intestines?

atropine, papaverine, metamizolum natricum

What are stomachic drugs used for?

promoting appetite or assisting digestion

What are digestant drugs used for?

promotes or aids digestion

What are antacids used for?

neutralises stomach acidity

What are emetics used for?

induce vomiting

What are antiemetics used for?

suppress nausea and vomiting

What are adsorbent drugs used for?

absorb noxious substances on their surfaces and carry them out of the digestive system

What are astringent drugs used for?

form a protective layer between toxic substances and the epithelial surface in the GI tract

What are spasmolytic drugs affecting the forestomach used for?

relieve spasms of smooth muscle

What are antitympanic drugs used for?

decrease or prevent gas production

What are prokinetic drugs used for?

help control acid reflux

What is the most common digestive disorder affecting bovine species?

tympany

When does tympany occur?

after excessive food intake

What happens in tympany?

rumen content undergoes fermentation with consequent liberation of a large volume of gas, which is not regurgitated as rapidly and distends the walls of the organ, which paralyses movement and normal regurgitation becomes impossible

What effect can tympany have?

asphyxia due to pressure on the diaphragm

What types of tympany are there?

gas tympany, foam tympany

What class of drugs is used to treat gas tympany?

antitympanics

What class of drugs is used to treat foam tympany?

antifrothing drugs

What is gas tympany characterised by?

cumulation of gas in proventricles (ruminants) and in stomach and/or intestines (horses)

What is foam tympany characterised by?

decreased surface tension of the rumen content causes the formation of foam, trapping gas in the bubbles, so it cannot be eructated

When does foam tympany occur?

legume pastures or high concentrated rations are grazed or fed

What are examples of antitympanic drugs?

volatile oils (turpentine), formalin, phenol, chlorophorm, alcohol, calcium hydroxide

What physical methods can be used to treat the acute phase of gas tympany?

trocar, stomach tubing

What is the mode of action of antifrothing drugs?

increase the surface tension of the rumen content allowing them to break

What are examples of anti-frothing agents?

dimeticon, simeticon,
sunflower oil, olive oil, linseed oil

What are dimeticon and simeticon?

polymerised methylsilicones

How long after administration do dimeticon and simeticon act after oral administration?

5-15 minutes

How can dimeticon and simeticon be administered?

stomach tube or drench (diluted with water), or injected directly into the rumen

Chemically, what are adsorbents?

water insoluble, inert substances

What are adsorbents used to treat?

bacterial toxins, poisons of organic and inorganic origin, intestinal gases

What are examples of adsorbents?

activated charcoal, while clay (kaolin), tannins

What are the characteristics of activated charcoal?

fine, black, odourless powder that in insoluble in water or alcohol;
binds particles carrying both positive and negative charge;
broad spectrum activity and rapid action;
has a very large surface area (1g = 500-1500 m2)

What is given after activated charcoal is administered and why?

saline laxatives to accelerate passing of activated charcoal and toxin

What are the characteristics of kaolin?

binds to only electro-negative particles;
does not adsorb E.coli enterotoxins

When and where does kaolin have negative effects?

intestinal microflora after prolonged use

In which animals is kaolin less effective?

young animals

In which animals is kaolin more effective?

older animals

Where is kaolin used?

external to protect the skin (pastes, ointments, gels, powders)

What are examples of adstringents?

tannin and its derivatives, mucilage from linseed, pectins, bismuth salts

What are the characteristics of tannins?

bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids

What role does tannin play in plants?

protection from predation and in plant growth regulation

What is tannin used for the treatment of?

diarrhoea, toxicosis of alkaloids (atropine, morphine, strychnine)

What is administered after tannin and why?

saline bulk purgatives for rapid elimination

What bismuth salts are adstringents?

carbonate, salicylate, subnitrate

Why are bismuth salts used?

adsorbent acitvity,
absorb E. coli enterotoxins

What is bismuth carbonate used for in GIT other than adstringent effects?

antacid

What is bismuth salicylate used for in GIT other than adstringent effects?

local anti-inflammatory effect (inhibition of prostaglandin synthesis)