Download Prescribing in Disease

Prescribing in Disease
Clive Roberts
So what are drugs good at treating (or
preventing)?
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Pain
Inflammation
Infection
Fluid retention
Heart problems
High blood pressure
Epilepsy
Parkinsonism
Asthma / COPD
Peptic ulcer disease
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Diarrhoea/constipation
Depression
Anxiety/sleeplessness
Psychosis
Metabolic /endocrine
diseases
Malignant disease
Degenerative disease
Haematological
problems
Etc Etc
What could happen to this man?
1) Massive fluid overload
2) Hepatic encephalopathy
3) Gross electrolyte abnormality
4) Renal Failure
5) GI or other Haemorrhage
6) Metabolic abnormaility
7) Exacerbation of liver disease
8) Infection
9) Drug accumulation
And so the risks of drug use in decompensated liver
disease
• Precipitate encephalopathy
– CNS effect
– Electrolyte effect
– GI effect
• Worsen metabolic effect/features of hepatic failure
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Fluid retention
Sodium retention
Electrolyte abnormality
Hypoglycaemia
Clotting abnormalities
Continued:
• Profound pharmacokinetic disturbance leading to drug
accumulation and dose related adverse effects
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Decreased systemic clearance of lipid soluble drugs
Increased bioavailability of drugs with high extraction ratio
Decreased plasma protein binding
Altered apparent volume of distribution
Associated impairment of renal function
Failure of pro-drugs
Hepatic blood flow reduction
• Worsened hepatic state
– Hepatotoxic drugs
Some examples from the BNF table
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Anticoagulants
Antidepressants, anxiolytics and hypnotics
Anti-psychotics
NSAIDs
Diuretics
Phenytoin, Carbamazepine
Glibenclamide
Opioids
Rifampicin
• Co-amoxyclav, clarythromycin,
erythromycin, ketoconazole, isoniazid
• Chloramphenicol
• Clopidogrel
• Cyclophosphamide, methotrexate
• Lignocaine
• ACE inhibitors
• Metformin
• Verapamil and some dihydropyridine Ca
blockers
• Statins
• Antacids
• Theophylline
Other risk situations
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Renal disease
The Elderly
Need for many drugs
Allergy
Lung disease
Heart disease
Gastrointestinal disease
Inherited diseases
Blood diseases
Bone disease
Skin disease
Pregnancy
The renal patient
• Pharmacokinetic disturbance
– Mainly affecting drug clearance
– Also protein binding
• Increased sensitivity
• Poor tolerance of adverse effects
• Decreased effectiveness of some drugs
Drugs in the elderly
• Multiple indications leads to polypharmacy
• Pharmacokinetic disturbance of
metabolism, excretion, protein binding and
drug distribution
• Increased sensitivity to the actions of drugs
on CVS, CNS, GIT
• Poor tolerance of adverse effect
Other risk situations
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Renal disease
The Elderly
Need for many drugs
Allergy
Lung disease
Heart disease
Gastrointestinal disease
Inherited diseases
Blood diseases
Bone disease
Skin disease
Pregnancy
Remember
• Every disease represents a potential contraindication to particular drugs
• Prescribing any drug should only follow a
decision that potential benefit outweighs
potential risk