Prescribing for Specific Groups

Question 1

Who are these specific groups of patients you need to be wary of when prescribing ?

Answer 1

• Patients with hepatic or renal impairment
• Elderly
• Pregnant women
• Breastfeeding women
• Neonates, infants, young people, “children”
• Terminally ill/end of life
• Ethnic minorities or if English is not their first language
• Incapacitated patients
• Culturally diverse groups e.g. Travellers, immigrants, refugees
• Patients unable to consent to treatment
• A typical patient group in your own specialist area e.g. respiratory patients or patients with mental health problems
• Those with co-morbidities
• Others?

Question 2

Explain Prescribing in Hepatic Impairment

Answer 2

• The liver is the main drug to metabolise drugs.
• Hypalbuminaemia (hypoproteinaemia) in severe liver disease limits availability for drug binding, thus increasing unbound concentration
  Toxicity may occur in highly protein bound drugs with a narrow therapeutic index eg phenytoin or prednisolone.
• Hepatic encephalopathy, ascites and deficiencies in clotting factors can increase sensitivity to some drugs
• Drugs that cause sedation, constipation or hypokalaemia are contraindicated in severe liver disease as these can cause encephalopathy e.g. opiates & benzodiazepines
• Ascites may be worsened by any drug that causes fluid retention e.g. NSAIDs
• Anticoagulants will require careful monitoring if used at all & care with aspirin, NSAID
• Hepatotoxcitity – Many drugs can cause liver damage and theoretically should be avoided in patients with liver disease
• In practice most can be used safely with dose adjustment e.g. paracetamol EXCEPT:
• Methotrexate in alcoholic liver disease

Question 3

Prescribing in renal impairment

Answer 3

• The kidney is a major organ involved in excretion of drugs
• Any decrease in GFR can potentially affect drug clearance
• Reduced excretion of a drug (or its metabolites) can cause toxicity
• Sensitivity to some drugs is increased even if elimination is unimpaired;
• Many side effects are poorly tolerated by patients with renal impairment (Pharmacodynamic effects)
• Some drugs are ineffective when renal function is reduced
• Nephrotoxic drugs should be avoided if possible in patients with renal disease
• Many of these problems can be avoided by reducing the dose or by using alternative drugs.
• If even mild renal impairment is considered likely on clinical grounds, renal function should be checked before prescribing any drug which requires dose modification.

Question 4

What are nephrotoxic drugs

Answer 4

Nephrotoxins
* Antibiotics (gentamycin)
* NSAIDs and COX-2 inhibitors (naproxen)
* ACE inhibitors and ARBs (ramipril)
* Diuretics (Bendroflumethiazide)
* Renally cleared drugs (insulin)