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An ABC of Drug-Related Problems. RHB Meyboom, M Lindquist, ACG Egberts Drug Safety 2000;22:415-23. Introduction. The percentage of hospital admissions due to adverse drug reactions in some countries is about or more than 10% Br J Clin Pharmacol 1998, 45(3), 301-308. - PowerPoint PPT Presentation
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An ABC of Drug-Related Problems
RHB Meyboom, M Lindquist, ACG Egberts
Drug Safety 2000;22:415-23
Introduction
• The percentage of hospital admissions due to adverse drug reactions in some countries is about or more than 10%
• Br J Clin Pharmacol 1998, 45(3), 301-308.
• Thèrapie, 1999, 54(1) 21-27. • Ad Drug React Toxico Rev., 1998,
17(1), 19-50.• Norway 11.5%, France 13%, UK 16%
6.7% of hospital patients have serious adverse drug reactions (medication error excluded)Lazarou J. Pomeranz BH, Corey PN. JAMA 1998;279:1200-5
16.2% of hospital admissions are drug-related Therapeutic failure 54.8%Adverse reactions 32.9%Overdose 12.3%
Avoidable 49.3%
Nelson KM, Talbert RL. Pharmacotherapy 1996;16:701-7
• Some countries spend up to 15-20% of their hospital budget dealing with drug complications.– White T et al. Counting the cost of
drug-related adverse events. Pharmacoeconomics, 1999, 15(5). 445-458.
Type A adverse effects Drug actions
Interactions
Type B adverse effects Patient reactions
Type C adverse effectsStatistical effects
Ineffectiveness
Poisoning
Noncompliance Medication error
DependenceLate effectsCarcinogenesis
Organ selective injury
Risk situations
The Zodiac of Drug-Related Problems
Type A adverse effects - Drug actions
Pharmacological side effects
• Common (> 1 %)
• Dose relationship
• Suggestive time relationship (kinetics)
• Reproducible
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type A adverse effects - Drug actions
Examples:•Sedation•Constipation•Diarrhoea•Urinary retention•Impotence•Hypoglycaemia (antidiabetics)•Hypokalaemia (diuretics)•Baldness (oncolytics)
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type A adverse effects - Drug actions
• Organ selective injury
• Long-term use effects
• Carcinogenesis
• Risk situations, e.g.- childhood- elderly- pregnancy- lactation- renal failure- haemodialysis
• Interactions
Type A adverse effects - Drug actions
Methods of study:
• Clinical trial / follow-up study
• Spontaneous reporting
• Prescription event monitoring
• Hospital studies
• Experiments
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type B adverse effects - Patient reactions Rare (< 1 %) No dose relationship Unexpected Mechanism uncertain Causality uncertain Not reproducible Characteristic, serious Suggestive time relationship Low background frequency
Type B adverse effects - Patient reactions Immunoallergic reactions Pseudoallergy Metabolic intolerance Idiosyncrasy
Examples: • Anaphylaxis• Stevens-Johnson syndrome• Blood dyscrasias• Hepatitis
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type B adverse effects - Patient reactions
Methods of study:
• Spontaneous reporting
• Prescription event monitoring
• Case control surveillance
• Large databases / record linkage
Type C adverse effects - 'statistical
effects'
Increased frequency of 'spontaneous' disease
• High background frequency
• Less typical for a drug reaction
• No suggestive time relationship
• Often long latency
• Mechanism unknown
• Not reproducible
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type C adverse effects - 'statistical effects'
Examples:
• Thromboembolic events
• GI haemorrhage
• Pancreatitis
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type C adverse effects - 'statistical effects'
Methods of study:
• Follow up studies (large scale, long-term)
• Case control studies
• Large databases / record linkage
Spontaneous Reporting of limited use
Ineffectiveness55% of drug related problems
• Limited efficacy• Noncompliance• Pharmaceutical defect (counterfeit; generic)• Interaction• Resistance• Tolerance
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Inappropriate use• Wrong dose• Wrong duration• Wrong indication• Wrong administration• Wrong patient • Wrong attitude or expectations
- Noncompliance
- Medication error
- Negligence (contraindication)
- Failure of information, counseling
or monitoring
Medication Error
> 7000 deaths per year from medication error in the USA
To Err is Human: Building a Safer Health System. National Academy Press, 1999
Inappropriate use
Methods of study:
• Spontaneous reporting
• Questionnaire
• Hospital studies
• Follow-up studies
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Dependence• hidden• not only narcotics
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Poisoning (overdose)• iatrogenic• accidental• intentional
Drug actionsType A adverse effects
Interactions
Patient reactionsType B adverse effects
Statistical effectsType C adverse effects
Non-compliance
Overdose
Therapeutic failure
Dependence
Organ selective toxicity
Delayed effects
Special situations
Type A adverse effects Drug actions
Interactions
Type B adverse effects Patient reactions
Type C adverse effectsStatistical effects
Ineffectiveness
Poisoning
Noncompliance Medication error
DependenceLate effectsCarcinogenesis
Organ selective injury
Risk situations
The Zodiac of Drug-Related Problems
Definitions (WHO)• Side Effect: any unintended effect of a drug
occurring at normal doses, which is related to the pharmacological properties of the drug
• Adverse Event: any untoward medical occurrence that may present during treatment with a drug but does not necessarily have a causal relationship
• Adverse Reaction: any response to a drug which is noxious and unintended and occurs at normal doses
Often only suspicions!
Edwards IR, Biriell C. Drug Safety 1994;10:93-102