Clinical Pharmacology Flashcards by Annie Caldwell

Drugs for acid suppression

Antacids
Alginates
H2 receptor antagonists
Proton pump inhibitors

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What drugs affect GI motility?

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

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Drugs used to treat IBD

Aminosalicylates
Corticosteriods
Immunosuppressants
Biologics

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What drugs affect intestinal secretions?

Bile acid sequestrants

Ursodeoxycholic acid

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Features of antacids

Neutralise gastric acid

Taken when the symptoms occur

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Example of an antacid

Maalox

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Example of an alginate

Gaviscon

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How do alginates work?

Form a viscous gel that floats on the stomach contents and reduces reflux

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How do H2RA work?

Block histamine receptor and therefore reduce acid secretion

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Example of a H2RA

Ranitidine

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What is H2RAs indicated in?

GORD

Peptic ulcer disease

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How do PPIs work?

Irreversibly block proton pump and therefore reduce acid secretion

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What are PPIs indicated in?

GORD
Peptic ulcer disease
In triple therapy for H pylori

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Example of a PPI

Omeprazole

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S/Es/Complications of PPI use

GI upset
Predisposition to C diff
Hypomagnesia
B12 deficiency

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What do prokinetic agents do?

Increase gut motility and gastric emptying

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Examples of drugs that decrease motility

Loperamide (immodium)

Opiods

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What can anti-spasmodics be used in?

IBS

Renal colic

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How do drugs that decrease motility of the gut work?

Via opiate receptors in GI tract to decrease ACh release

increased smooth muscle contraction
increased anal sphincter tone

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Types of anti-spasmodics

Anti-cholinergic muscarinic antagonists
Direct smooth muscle relaxants
CCBs (peppermint oil)

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How do anti-cholinergic muscarinic antagonists work?

Inhibit smooth muscle contraction in the gut wall, producing muscle relaxation and reduction spasm

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How do CCBs work as anti spasmodics?

Reduce calcium required for smooth muscle contraction

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Types of laxatives and an example of each

Bulk (Isphagula)
Osmotic (lactulose)
Stimulant (senna)
Softeners (arachis oil)

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How do laxatives work?

By increased bulk or

Drawing fluid into the gut

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Adverse effects of aminosalicylates for IBD

GI upset Blood dyscarias Renal impairment

Examples of aminosalicylates for IBD

Mesalazine | Olsalazine

Complications of corticosteriods for IBD

Osteoporosis Cushings Increased susceptibility to infection Addisonian crisis with abrupt withdrawal

Example of an immunosuppressant used for IBD

Azathioprine

How do immunosuppressants work in IBD?

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

S/Es of immunosuppressants in IBD

Bone marrow suppression Azathioprine hypersensitivity Organ damage (lung, liver, pancreas) Numerous drug interactions

Examples of biologics used in IBD

Anti-TNFa antibodies e.g. infliximab

How do biologics work in IBD?

Prevents action of TNFa (key cytokine in inflammatory response) Addresses inflammatory response but not underlying disease process so course of disease after discontinuation is unclear

Contraindications to infliximab

Current TB / other serious infections MS Pregnancy/breast feeding

S/Es of infliximab

``` Risk of infection, particularly TB Infusion reaction (fever, itch) Anaemia Thrombocytopenia Neutropenia May cause demyelination Pleurodynia Malignancy ```

Definition of pleurodynia

Severe pain in the muscles between the ribs or in the diaphragm

Examples of other biologics to control IBD

Certolizumab Adalimuab Natalizumab

How does cholestyramine work?

Reduces bile salts by binding with them in the gut and then excreting them as an insoluble complex

S/Es of cholestyramine

May affect absorption of other drugs | May affect fat soluble vitamin absorption - so may decrease vit K levels

What is ursodeoxycholic acid used to treat?

Gallstones | Primary Biliary cirrhosis (PBC)

How does ursodeoxycholic work?

Inhibits an enzyme involved in the formation of cholesterol, altering the amount of bile and slowly dissolving non-calcified stones

Processes of a drug

Absorption Distribution Metabolism Excretion

How could the absorption of a drug be altered due to the GI tract?

Ph Gut length Transit time e.g. digoxin, warfarin

How could the distribution of a drug be altered due to the GI tract?

Low albumin

How could the metabolism of a drug be altered due to the GI tract?

Liver enzymes Increased gut bacteria Gut wall metabolism (first pass metabolism) Liver blood flow

How may the excretion of a drug be altered due to the GI tract?

Biliary excretion (increased toxicity if hepatobiliary disease)

What drugs can cause diarrhoea / constipation?

Cholinergics Antimicrobials Opiates Anticholinergics

Which type of drug in particular is associated with diarrhoea as an adverse effect?

Antimicrobials

What type of drug in particular can cause changes to the gut bacteria?

Antimicrobials

What drug in particular can antibiotics effect? Why?

OCP Relies on metabolism/circulation by gut bacteria Antibiotics kill of the gut bacteria so reduce metabolism/circulation and therefore reduces the effectiveness of the OCP

Effects of using antimicrobials on the gut

Diarrhoea Reduced OCP effectiveness Reduced vit K absorption (increased prothrombin time) Overgrowth of pathogenic bacteria (C diff)

Types of drug induced liver injury

Intrinsic hepatotoxicity | Idiosyncratic hepatotoxicity

Differences between intrinsic and idiosyncratic hepatotoxicity

Intrinsic - predictable, dose dependent, acute | Idiosyncratic - unpredictable, non dose dependent, may occur at any time

Risk factors for liver disease

``` Elderly Female Alcohol consumption Genetics Malnourishment ```

What drugs can cause acute hepatitis?

Paracetomal Isoniazid Ritonavir Troglitazone

What drugs can cause chronic hepatitis?

Diclofenac Methyldopa Minocycline Nitrofurantoin

What drugs can cause acute cholestasis?

ACE inhibitors Co-amoxiclav Chloropromazine Erythromycins

What drugs can cause non alcoholic steatohepatitis?

Amoidarone | Tamoxifen

What drugs can cause fibrosis/cirrhosis of the liver?

Methotrexate

What drugs can cause veno occlusive disease?

Cyclophosphamide

What classification is used to classify the severity of liver disease?

Child-Pugh Classification

What types of drugs should you take care in prescribing in liver disease?

Drugs which can be toxic due to changes in pharmacokinetics Hepatotoxic drugs - methotrexate - azathioprine Drugs which may worsen the non liver aspects of liver disease (e.g. encephalopathy) e.g. benzodiazepines

Why should care be taken if prescribing warfarin/anti-coagulants?

Clotting factors are already low in liver disease

NSAIDs in liver disease

Can worsen ascites due to fluid retention

Opiates/benzodiazepines in liver disease

May precipitate encephalopathy by increasing sedation