What types of drugs are most commonly associated with drug reactions?
- Opioid Analgesics
Who is at high risk for Drug-Drug interactions?
- Multiple drugs to treat one disorder
- Multiple disorders requiring different drugs
- OTC Meds, Caffeine, Nicotine, Alcohol, etc
What kind of increases can Drug-Drug Interactions cause?
- Increased Therapeutic effects: such as sulbactam and ampicillin
- Increased Adverse effects: such as with aspirin and warfarin or alcohol
What kind of decreases can Drug-Drug interactions cause?
- Reduces Effects: Inhibitatory- interactions that result in reduced effects
- Reduced Therapeutic effect: Such as Propranolol and albuterol
- Reduced Adverse Effects: such as naloxone to treat opioid/narcotic overdose
What is one key body mechanism that Drug-Drug interactions can change?
Metabolism of the drug or of another drug, making it ineffective or toxic
What are the four basic mechanisms through which drugs can interact?
- 1. Direct chemical or physical interaction
- 2. Pharmacokinetic interaction
- 3. Pharcodynamic interaction
- 4. Combined toxicity
What is an example of direct chemical or physical interaction of medications?
- Combining drugs in the same container, such as with an IV bag
- If you see precipitate, do not administer
- if you do not know if 2 solutions are compatible to mix, look it up and ask the pharmacist!
What are the Pharmacokinetic drug-drug interactions?
- Altered Absorption: drugs that may inhibit absorption of other drugs across membranes
- -such as anti-ulcer drugs that coat the stomach may decrease GI absorption of other drugs
- Altered Metabolism: Most important and most complex mechanism in which drugs interact
What are the mathematical models for Addition, Synergism, Potentiation and Antagonism interactions?
- Additions: 1+1=2
- Synergism: 1+1=3
- Potentiation: 0+1=2
What are some of the clinical significances of Drug-Drug interactions
- Risk for serious drug interaction is directly proportionate to the number of drugs a client is taking
- Drug interactions have the potential to significantly impact the outcome of therapy
- Many interactions have yet to be identified
What are some ways to minimize the risk of drug interactions?
- Be knowledgeable of high risk drugs and those with a narrow TI
- Be knowledgeable of which clients are high risk (diabetes, asthma, cancer, renal and cardiac disease, pregnant clients
- Advocate for your clients that they only receive what is necessary
- Take a thorough drug history upon admission (including illicit drug use)
- Monitor for early signs of toxicity
- Monitor blood levels for drugs with a narrow TI such as Digozin, litium, phytoin (Dilantin), carbamazepine (Tegretol), and warfarin (coumadin)
What is the biggest Drug-Food Interaction?
Unless a drug needs to be administered on an empty stomach or with food, what is a good way to time medication?
2 hrs before or after meals to avoid interactions
What is the role of the FDA is drug reactions?
The Adverse Event Reporting System (AERS) and Medwatch safety information
According to WHO, what are ADR (ADE)?
- Adverse Drug Reactions/Events are any noxious, unintended, and undesired effect that occurs at normal drug doses
- Can range from annoying to life threatening
What terms are used with ADR?
- Side effects
- Allergic Reaction
- Idiosyncratic Effect
- Iatrogenic disease: caused by medical treatment
- Physical dependence
- Carcinogenic effect: Cancer Causing
- Teratogenic effect: birth defects
What drugs most commonly cause allergic reactions?
Also sulfonamides, diuretics and oral hypoglycemic agents
Why do drugs cause hepatotoxicity?
- Most drugs are metabolized in the liver
- Medications are the number 1 cause of liver failure in the US
What are the s/s of liver injury?
Jaundice, dark urine, light-colored stools, n/v, malaise, abdominal discomfort, loss of appetite
What are some questions to ask when identifying an ADR?
- Did the symptoms appear shortly after the drug was first used?
- Did symptoms disappear/lessen when the drug was discontinued?
- Did symptoms reappear when the drug was restarted
- Is the illness itself sufficient to explain the event?
- Are other drugs in the regimen sufficient to explain the event?
What is a black box warning?
- Strongest safety warning a drug can carry and still remain on market
- Very high risk
- Concise summary of adverse effects of concern in black with black border
What factors can determine an individual's drug response?
- Body weight and composition
- Pathological diseases like kidney and liver disease as well as acid-base imbalances
What factors play into variability in absorption?
- Bioavailability- ability of drug to reach systemic circulation from the site of administration, esp with PO meds
- Changes in pH
- Diarrhea, constipation, food in stomach
What does it mean if someone develops a tolerance?
- A client will exhibit a decreased response to a drug as a result of repeated drug administration
- Requires higher doses
- One phenomenon of addition
What are some drugs associated with tolerance?
- Rare-local anesthetics
How do race and gender also effect variation in drug response?
- Gender: Alcohol is metabolized more slowly by women, certain opiod medications are more effective in women, Quinidine causes greater Qt interval prolongation in women
- Race: Genetic variations and psycho-social factos