Medicine safety
السلامة والامن الدوائيMedicine safety
Principles in the use of medicines
• Medicines should be used only when they are necessary.
• The benefit of administration of medicines should be considered in relation to the risk involved.
Examples of benefits vs. risk of medicine use :-
• Antibacterials: treating infection vs. occurrence of gastrointestinal side-effects .
• Anticancer agents: increased life expectancy vs. gastrointestinal side-effects, hair loss.
Drugs and driving:-
• Whenever a product that is likely to affect ability to drive is dispensed, patients should be advised.
• These effects are increased by consumption of alcohol.
Examples include hypnotics such as benzodiazepines (e.g. lorazepam) or antihistamines (e.g. Chlorpheniramine).
Safety in the home :-
1- To keep all medicines out of reach of children
(note :- use of child-resistant containers)
2- Safe disposal of unwanted medicines
3- Storage at appropriate conditions for the specific medicine e.g. :-
- storing in the refrigerator for products required to be kept at 2–8◦ C e.g. insulin and vaccines .
- storing in a cool place for products requiring storage temperature ranging between 8 and 15◦C e.g. Human chorionic gonadotropin .
- storing at room temperature for products requiring storage between 15 and 25◦C .
4- Proper labeling on container to include dosage regimen and cautionary labels (e.g. ‘Warning: may cause drowsiness’). Include advisory labels (e.g. ‘Shake the bottle’)
5- Do not change containers or remove from carton .
Cautionary labels
e.g.
1- Warning :- May cause drowsiness. If affected do not drive or operate machinery e.g. antihistamine-containing preparations .
2- Warning :- Avoid alcoholic drink e.g. metronidazole .
3- Do not take indigestion remedies at the same time of day as this medicine (e.g. enteric-coated tablets).
4- Do not take indigestion remedies or medicines containing iron or zinc at the same time of day as this medicine (e.g. tetracyclines, quinolones).
5- Take at regular intervals. Complete the prescribed course unless otherwise directed e.g. antibacterial medications.
6- take with or after food (e.g. non-steroidal anti-inflammatory drugs).
7- Swallow whole, do not chew (e.g. enteric-coated and modified-release oral formulations such as omeprazole).
8- To be spread thinly (e.g. corticosteroid preparations for application on the skin).
Advisory labels
e.g.
1- Shake the bottle e.g. calamine lotion.
2- For external use only e.g. for products to be applied externally.
3- Discard 4 weeks after opening e.g. eye drops.
4- This medicine may colour the urine (brown colour) e.g. levodopa.
Barriers to proper use of medicines
1- Patient incompliance and inadherence with treatment
2- Patient confusion
3- Communication problems
4- Side-effects
5- Dispensing errors
6- Cost of medicines
7- non-Accessibility and non-availability.
Liver disease
1- Liver disease may alter the response to drugs due to impaired drug metabolism.
2- Drug prescribing should be kept to a minimum in all patients with severe liver disease and doses need to be reviewed in patients with liver disease.
For example, the use of paracetamol in patients with liver disease:- dose-related toxicity may occur, large doses should be avoided.
Renal impairment
1- The use of drugs in patients with reduced renal function can give rise to problems such as failure to excrete drug or its metabolites.
2- In patients with renal impairment dose adjustment is recommended.
Drug-related problems
• Untreated indications
• Drug therapy not indicated
• Improper drug selection
• Sub-therapeutic dose
• Failure to receive drug
• Overdose or toxic dose
• Adverse drug reactions
• Drug interactions.
Adverse drug reactions
• Any drug may produce unwanted or unexpected adverse reactions.
• Detection and recording of adverse drug reactions (ADRs) are important.
Definitions
• Side-effect: ‘Expected, well-known reaction resulting in little or no change in patient management.’ The effect has a ‘predictable
frequency’.
• Adverse drug reactions: ‘An unexpected, unintended, undesired or excessive response’ to a drug with sequelae.
An ADR can lead to (sequelae of ADRs):-
• drug discontinuation
• dose modification
• hospital admission
• prolonged hospitalization
• requirement of supportive treatment
• complication of diagnosis
• negative impact on prognosis
• temporary/permanent harm, disability or death.
Adverse drug reaction monitoring and reporting programmes
· ADR surveillance: monitoring occurrence.
· ADR documentation: documenting incident.
· Reporting of ADRs: reporting to national regulatory authority (e.g. MHRA in the UK). MHRA = medicines and healthcare products regulatory agency
The national regulatory authority undertakes coordination and monitoring of suspected ADRs on a local and an international level.
• Pharmacists should participate in mechanisms that monitor the safety of drug use in high-risk populations (e.g. older people, children, HIV patients).
• Pharmacists should lead education of health professionals regarding potential ADRs.
Processes of an ADR monitoring programme
1- Monitoring
2- Detecting
3- Evaluating
4- Documentation
5- Reporting to authorities
6- Updates and discussions with healthcare team members.
Pharmacist actions in an ADR monitoring programme:-
1- Analysis of ADR reports
2- Identification of drugs and patients at high risk
3- Participation in the development of policies and procedures and description of responsibilities of healthcare professionals in the programme.
4- Development and maintenance of the programme in an institution.
5- Educating prescribers and other health professionals on the implementation and running of an ADR programme
6- Dissemination of information obtained from the programme
7- Reporting to authorities.
Drug interactions
- Administration of two or more drugs at the same time may lead to an exertion of their effects independently or may cause an interaction .
- The interaction may be potentiation or antagonism of one drug by the other.
- Occurrence and impact of drug interactions should be evaluated on the basis of :-
1- clinical significance.
2- potential for hazardous outcomes.
Examples of clinically significant drug interactions :-
1– aspirin/ibuprofen + warfarine → enhanced anticoagulant effect.
2– aspirin/ibuprofen + phenytoin → enhanced effect of phenytoin.
Medication errors
These may occur as a result of inappropriate drug prescribing.
For example :-
- cisapride was withdrawn from the market because the drug could not be used safely due to its interaction with macrolides or due to inappropriate patient monitoring.
( cisapride were withdrawn due to their high potential for inhibiting certain CYP enzymes and causing fatal cardiac arrhythmias when combined with certain CYP- enzyme inhibitors )
Types of medication errors
1- Prescribing error: medication prescribed is inappropriate.
2- Dispensing error: medication dispensed is inappropriate (e.g. due to incorrect interpretation of the prescription).
3- Omission error: dose skipped or medication is not being administered.
4- Wrong time error/improper dose error/wrong administration technique error: medication administered in an incorrect manner.
5- Deteriorated drug error: medication dispensed is not of good quality.
Practices to reduce medication errors
1- Avoid unnecessary use of decimal points:
- quantities less than 1 gram should be written in milligrams
- quantities less than 1 milligram should be written in micrograms .
2- Avoid use of abbreviations: micrograms and not μg, nanograms and not ng .
3- Names of drugs written clearly and not abbreviated.
Pharmacists and prevention of medication errors
1- Participation in drug therapy monitoring .
2- Participation in selection of appropriate drug therapy.
3- Establish contact with nurses and physicians.
4- Maintain medication profiles
5- Participation in procurement, distribution and storage of drugs in pharmacy and at ward level.
6- Check calculations
7- Confirm confusing medication orders.
8- Storage guidelines: avoid having lookalike medications stored close to each other, use of containers and labels to reduce risk of confusing medications
9- Documentation systems to trace medication dispensing error .
Managing medication errors :-
1- Classification of medication errors.
2- Determination of cause.
3- Documented and reported.
4- Corrective actions identified and documented.
5- Supportive therapy to patient.
6- Quality improvement programme and dissemination of corrective action.
Classification of medication errors according to risk
medication errors classified into six levels of severity, according to the following :-
1 - No clinically significant harm to the patient occurred.
2 - Need to increase patient monitoring but no patient harm.
3 - Change in vital signs but no ultimate patient harm occurred.
4 - Need for treatment with another drug or increased length of stay in hospital.
5 - Permanent patient harm occurred.
6 - Patient death occurred.
Poisoning
• All patients who show features of poisoning should generally be admitted to hospital.
• Poisoning may take place with :-
- immediate action poisons (e.g. alcohol (ethanol)) or
- delayed action poisons (e.g. paracetamol).
• It may be difficult to establish with certainty to identity of the poisoning agent and the size of dose administered, particularly in cases of premeditated poisoning.
• Supportive care is undertaken and treatment is aimed at managing symptoms (e.g. hypertension). Vital functions should be monitored.
Methods to remove the poisons:-
1- Removal of the poison from the gastrointestinal tract :-
• Carried out by gastric lavage.
• Only considered if a life-threatening amount of a poison has been ingested within the preceding hour.
2- Prevention of absorption of poison
• Carried out by using activated charcoal.
• Charcoal binds to many poisons and reduces their absorption. It is relatively safe and the sooner it is given the more effective the
procedure will be.
3- Use of antidotes:-
This is limited in that antidotes are available for only a few poisons:
1- Paracetamol: acetylcysteine to protect the liver if given within 10–12 hours of ingestion of the excessive dose .
2- Iron:- desferrioxamine which chelates iron.
3- Opiate poisoning presents with sedation, cough suppression and respiratory depression leading to coma. The antidote naloxone, is an opioids receptor antagonist available as an IV injection.
4- Enhancing elimination of poison by alkalinisation of urine:-
• Aspirin is an acid.
• Poisoning with aspirin is associated with stimulation of respiratory centre (hyperpnoea) and abdominal pain, nausea, tinnitus, deafness, vertigo.
• Rehydration and alkalinisation of urine to enhance drug elimination will promote ionization of aspirin, thus preventing reabsorption in the kidney.
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