Clinical Pharmacology of Alimentary Flashcards Preview

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Flashcards in Clinical Pharmacology of Alimentary Deck (30)
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1
Q

What are the main drug classes used in the treatment of alimentary disease?

A
Antacids
Alginates
Other mucosal protectors
H2 Receptor antagonists 
Proton pump inhibitors
2
Q

What is the purpose of antacids?

A

Neutralise gastric acids when symptoms occurs

3
Q

What is the purpose of alginates?

A

Reduces reflux by forming a viscous gel that floats on the stomach contents

4
Q

What is the purpose of H2 receptor antagonists?

A

Block histamine receptors to decrease acid secretion

Has GI side effects

5
Q

What is the purpose of Proton pump inhibitors?

A

Block proton pump

6
Q

What drug types affect motility?

A

Anti-emetics
Anti-muscarinics/other anti-spasmodics
Anti-motility

7
Q

What is renal colic?

A

Kidney stones move to the ureter

8
Q

In what way do the three mechanisms help to reduce GORD symptoms?

A
  1. Anti-cholinergic muscarinic antagonists (Hyoscine (Buscopan) & Mebeverine) inhibit smooth muscle constriction in the gut wall, producing muscle relaxation and reduction spasm
  2. Smooth muscle relaxants
  3. Calcium-channel blockers (pep permint oil) reduce calcium required for smooth muscle contraction
9
Q

What are the four types of laxatives?

A

Bulk - Isphagula
Osmotic - Lactulose
Stimulant - Senna
Softeners - Arachis oil

10
Q

What are the issues with laxatives?

A

Obstruction
Route of administration
Need for other measures
Misuse

11
Q

What drugs are used for IBD?

A
Aminosalicylates
Corticosteroids
Immunosuppressants
Biologics
*First two are anti-inflammatory*
12
Q

What do immunosuppressants do?

A

Prevents the formation of purines required for DNA synthesis so reduces immune cell proliferation

13
Q

What do biologics do?

A

Prevents action of TNfα (Key cytokine in inflammatory response) so addresses the response but not the underlying disease process

14
Q

What are the contraindications to infliximab?

A

Current TB or other serious infection
MS
Pregnancy/breast feeding

15
Q

What are the adverse effects of infliximab?

A

Infection risk
Infusion reaction - Fever/Itch
Anaemia/Thrombocytopenia/Neutropenia
?Demyelination

16
Q

What two drugs affect biliary secretions?

A

Cholestyramine

Ursodeoxycholic acid

17
Q

What does cholesytramine do?

A

Pruritis from biliary cause and reduces bile salts by binding with them in the gut and then excreting as an insoluble complex May decrease vitamin K levels and should be taken separately to any other drugs

18
Q

What does Ursodeoxycholic acid do?

A

Used for Gallstones and Primary Biliary Cirrhosis and it inhibits an enzyme involved in the formation of cholesterols, altering amount in bile and slowly dissolving non-calcified stones

19
Q

What is the problem with gastrointestinal or liver disease?

A

It can affect the processes of drug absorption, distribution, metabolism and excretion so GI symptoms may also necessitate a change in route of administration

20
Q

How can distribution be affected?

A

Low albumin

21
Q

How can metabolism be affected?

A

Increased gut bacteria can cause increased metabolism
Gut wall metabolism leading to a disease reducing first pass metabolism e.g. Morphine
Liver enzymes have variable effects but generally toxicity
Liver blood flow as some drugs have a high extraction ratio

22
Q

How can excretion of drugs be affected?

A

Biliary excretion results in an increased toxicity if a patient has hepatobiliary disease e.g. Spironolactone Look at lecture notes

23
Q

What are the adverse effects of GI drugs? (4)

A

GI upset
Diarrhoea/Constipation - Acute or Chornic e.g. NSAIDs
GI Bleeding/Ulceration - Most commonly due to a low dose os aspirin
Changes to gut bacteria

24
Q

How do changes in gut bacteria occur?

A

Mainly antibiotics causing a reduced a vitamin K absorption which caused an increased prothrombin time (Increased time for blood to clot)

25
Q

What are the three types of drug induced liver injury?

A

Type A ADR (Intrinsic Hepatoxocity)
Type B ADR (Idiosyncratic Hepatoxocity)
Drug itself or an active metabolite

26
Q

How can a type A ADR be determined?

A

Predictable
Dose-dependent
Acute

27
Q

How can a type B ADR be determined?

A

Unpredictable
Not dose-dependent
Can occur at any time

28
Q

What classification is used to assess the severity of Liver Disease?

A

Child-Pugh classificaiton

A = 9

29
Q

What types of drugs should be avoided?

A

Drugs that are toxic due to many changes in pharmacokinetics
Hepatotoxic e.g. Methotrexate
Going to worsen the non-liver aspects of liver disease e.g. Ascites & Encephalopathy from Benzodiazepines

30
Q

What drugs should you be careful of?

A

Warfarin/Anti-coagulants – Clotting factors are already low in liver disease
Aspirin/NSAIDs – Can increase bleeding time/NSAIDs can worse ascites due to fluid retention Opiates/Benzodiazepines – May precipitate encephalopathy by increasing sedation