Drug Interaction: OTC,Drugs of abuse and Herbals

Drug Interaction: OTC ,Drugs of abuse and Herbals Nursing Pharmacology Lecture notes


Drug Interactions
An altered or modified action or effect of a drug as a result of an interaction with one or more other drugs
Example: warfarin and levofloxacin result in an excessive increase in the INR


Drug Interactions
Pharmacokinetics
Absorption
Change gastric pH
↑ or ↓ gastric emptying time
Forming drug complexes
Distribution
Drug concentration in the blood
Protein-binding "power" of the drug
Volume of distribution


Drug Interactions
Pharmacokinetics
Metabolism
Enzyme inducers
Enzyme inhibitors
Excretion
Drugs that alter urine pH
Drugs that alter kidney perfusion


Drug Interactions
Pharmacodynamics
Additive effects - 2 or more drugs of similar action are given and is the sum of the effects of the drugs
Synergistic effects – 2 or more drugs are given, one can potentiate effects of others and the sum is greater than expected combined effects
Antagonistic effects – 2 or more drugs are given and one negate the effects of others


Drug-Food Interactions
Food can increase, decrease or delay drug absorption
Example: dairy binds with tetracyclines
Example: food increases metoprolol absorption
Protein intake is important in protein-bound drugs
"Classic" interaction – MAOI and tyramine rich foods (wines, cheeses, beer, yogurt, sour cream, bananas) – results in norepinephrine release resulting in hypertensive crisis


Drug-Laboratory Interactions
Abnormal laboratory values (albumin, electrolytes, etc) can affect drug actions
Example: Hypokalemia with digoxin can result in digoxin toxicity

Drug-Induced Photosensitivity
Photosensitivity – skin reaction that can occur with exposure to sunlight
Examples:
Sulfa drugs
Tetracyclines
Methotrexate
Amiodarone

Over-the-Counter (OTC) Drugs
OTC drugs – those available without a prescription
FDA responsible for monitoring


Over-the-Counter (OTC) Drugs
Concerns with OTCs
Delays in diagnosis of potentially serious illness in those that self-treat
Symptoms may be masked making diagnosis difficult
Labels and instructions not clearly followed
Not consulting a healthcare professional before use
Potential for interactions with prescribed, otc, or herbal medications
Potential for overdose


Drugs of Abuse
Drug Misuse – indiscriminate use of a substance for a purpose other than which it is intended
Drug Abuse – drug use inconsistent with medical or social norms
An overindulgence in a substance that results in physical, psychological or social harm to an individual
Drug Addiction – compulsive, uncontrolled craving for the substance that causes severe physical or psychological reactions


Drugs of Abuse
Tolerance – reduced responsiveness of neurons in the brain leads to tolerance, requiring a larger dose of the substance to obtain the same "high"
Cue-induced craving – craving for the substance after a period of abstinence due to circumstances that prompt an association with the substance


Drugs of Abuse
Intoxication – state of being poisoned by the drug or substance
Detoxification – treatment to diminish or remove the substance or effects from the body
Withdrawal syndrome – s/s that occur in physically dependent persons when the substance is stopped
Alcohol, opioids, benzos cause strong reaction
Cannaboids, amphetamines weak reaction
Hallucinogens little to no reaction


Stimulants - Nicotine
Pharmacodynamics
Stimulates release of dopamine
Pharmacokinetics
Rapidly absorbed into blood from lungs; transfers easily into breast milk
Elimination 1-2h
Side Effects
CNS stimulation
Treatment
Nicotine replacement therapy; bupropion (Zyban), Chantix


Stimulants - Cocaine
Pharmacodynamics
Stimulates dopamine receptors resulting in rapid dependence; increases norepinephrine release
Pharmacokinetics
Peak depends upon route; duration generally lasts 60 – 90 min
Easily crosses placental barrier
Side Effects
CNS stimulation, mood swings, memory loss, paranoia, depression
Treatment
Control sx
Other tx remains investigational


Stimulants - Amphetamines
Pharmacodynamics
Similar to cocaine
Pharmacokinetics
Peak 60 -90 min, duration 2-4h
Side Effects
Increased alertness, anorexia, increased HR and BP, anxiety, paranoia
Treatment
Sx control
No specific medications helpful


Stimulants - Caffeine
Pharmacodynamics
Stimulates cns; diuretic effect
Pharmacokinetics
Peaks 1h
Side Effects
CNS irritability, insomnia, gastric hyperacidity, tachycardia
Treatments
Tx sx
Gradual reduction of caffeine


Depressants - Alcohol
Pharmacodynamics
Binds to dopamine receptors; CNS depressing effects
Pharmacokinetics
Food delays absorption
Metabolized at a constant rate (1drink/hr)
Side Effects
Relaxation, impaired judgment and motor skills, vomiting, coma, seizures, death
Treatments
Benzodiazepines, antipsychotics, disulfuram (Antabuse), naltrexone (ReVia), acamprosate (Campral)


Depressants – Sedatives/Hypnotics
Pharmacodynamics
CNS depressing effects
Pharmacokinetics
Effects can vary depending on route of administration
Side Effects
Respiratory depression, death, little cross-tolerance with opioids
Withdrawal peaks 2-3d short-acting, 7d for long-acting
Treatments
Flumazenil (Romazicon) – antidote for benzo OD
Sx control


Depressants - Opioids
Pharmacodynamics
CNS depressing effects
Pharmacokinetics
Vary depending upon route of administration
Side Effects
Drowsiness, slurred speech, flushed feeling, feeling of euphoria, respiratory depression, death
Treatments
Naloxone (Narcan) – antidote for OD
Methadone, Naltrexone (ReVia), Suboxone


Other Drugs of Abuse
Cannabis
Psychedelic Agents
Inhalants


Herbal Therapy
Herbal therapy – plant or plant part used for its medicinal properties
NOT approved by the FDA
Some oversight by the FDA and National Center for Complimentary and Alternative Medicine (Branch of NIH)


Herbal Therapy
Fresh herbs
Dried herbs
Extracts
Oils
Salves
Teas
Tinctures
Syrups


Common Herbal Remedies
Aloe
Used to tx burns, insect bites, psoriasis
Can be toxic if ingested in large quantities
Chamomile
Used for GI complaints, mild sedating effects
Careful with ragweed allergy
Echinacea
Used as immune booster
Uninterrupted use not recommended
Garlic
Used to lower cholesterol, blood pressure and anti-platelet activity, anti-infective properties
Can cause bleeding


Common Herbal Remedies
Ginger
Used for GI complaints, migraines, joint pain
Highly protein bound
Milk Thistle
Used to protect the liver
St John’s Wart
Used to treat depression and anxiety
Concerns with increased suicide risk
Valerian
Used to treat anxiety and insomnia


Concerns About Herbals
Little is known about many herbs
Some forms of administration safe, others toxic
Variability in purity and active ingredients
Patients consider these "natural" remedies and may not report their use unless specifically asked


Patient Education Related to Herbals
Avoid if pregnant (or attempting to conceive) or nursing
Avoid in young children
Treat the herb just like any other medicine
Store in a safe place
Use products from reputable companies and buy products from the same companies
Discuss herb use with your health care provider