How Drugs Act and Safe Prescribing Flashcards
What is an indication?
What is a contraindication? Name and describe the types of contraindications
Indication: a symptom suggests that a certain medical treatment is necessary
Contraindication: a specific situation in which a drug, procedure or surgery should not be used because it may be harmful to the person
- relative contraindication: acceptable if benefits outweigh risks
- absolute contraindication: life-threatening, do not take!
Name the three factors of dosage form selection:
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- Efficacy/ease of use
- Safety
- Patient access
What is a normal dosage interval based on?
Define this term:
Define an overdose:
- Normal dosage interval is based on 1 half life, the next dose is given when previous dose reaches half life
- Half-life: time taken for the total amount of drug in blood plasma to diminish by half once it reaches peak concentration
- Overdose: an excessive/dangerous dose of drug
List the three categories for drug interactions:
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Major: highly clinically significant - avoid combinations, risk of interaction outweighs benefit
Moderate: moderately clinically significant - use only in special circumstances
Minor: minimally clinically significant - minimise risk, consider alternative or institute monitoring plan
Name the drug-drug interaction mechanisms:
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- Pharmacodynamics: when effects or action of multiple drugs combine to produce adverse effects
- Pharmacokinetic: when one drug affects delivery of another drug to its target, may involve absorption, metabolism or elimination
- Pharmaceuticals: incompatibilities of ingredients
Why do you need to take care when prescribing in pregnant women?
What should you consider when prescribing to pregnant women?
Which drug is established as safe in pregnancy?
- Drugs can harm embryo or foetus at any stage during pregnancy, and we must assume if the drug is orally consumed, it crosses the placenta
- Benefits must outweigh the risks
- avoid prescribing if possible
- if essential, then use smallest effective dose of drugs extensively used which appear to be tested and safe
- Paracetamol is established safe in pregnancy
What do we need to consider when prescribing drugs to a breastfeeding mother?
Drugs taken by mother may pass into breast milk and affect the infant, therefore it is advisable to administer only essential drugs to a mother during breastfeeding
List things to consider when prescribing to children:
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Why may it not be sensible to prescribe a drug to a child?
- Dosing critical, by body weight
- Sugar free versions where available to prevent tooth decay
- Children may find it difficult to swallow a tablet/may need parental support
- Many drugs are not licensed for children so only necessary if benefits outweigh risks
Drug actions and pharmacokinetics may be different in children from adults, may cause delayed adverse reactions and many contain excipients not suitable for children
List some things to consider when prescribing to the elderly:
Prescribe to the elderly with caution:
- physiological function declines with age
- elderly more vunerable to adverse effects of drugs due to impaired renal elimination or increased sensitivity of target organs to drugs (brain, kidneys)
- nervous system more sensitive to drugs
- may be confused when/why to take them
- may have difficulty swallowing tablets
What is polypharmacy?
What does polypharmacy increase?
Someone taking a variety of drugs at the same time, common in the elderly
Polypharmacy increases risk of drug interactions as well as adverse reactions
Write a checklist before prescribing any drug:
- Check pt identity
- Pts age and gender
- Medical history/other conditions
- Any allergies
- Any recent/current medication
- Consider special conditions (pregnancy, lactation, swallow tablets)
- Sugar free suspension?
- Warn pt of any possible side effects
