Lecture 20: Misuse of OTC Drugs & Poisonings Flashcards
FDA definition of abuse
“the intentional, non-therapeutic use of a drug, even once, for its desirable or physiological effects”.
FDA definition of misuse
“the intentional use, for therapeutic purposes, of a
drug by an individual in a way other than prescribed by a health care provider
Misuse→
intent to treat therapeutic need
Abuse →
non-therapeutic use
Common Reasons for Misuse/Abuse of OTC Drugs
● Weight loss
● Suicide
● Euphoria
● Stimulant effects/wakefulness
Dextromethorphan
Used/abused for euphoria
○ ‘Robotripping’
Normal dose: up to 120mg, given in divided doses
Dextromethorphan Abuse dose
○ 100 -120mg per dose - restlessness and euphoria
○ >200mg - auditory/visual perception changes
○ >1000mg - complete dissociation and hallucinations
Dextromethorphan Mechanism of abuse:
Blocks NMDA receptor
○ Similar to abuse of PCP, ketamine
Dextromethorphan Risks
○ Serotonin syndrome
○ QT prolongation
○ CNS depression
○ Death
Dextromethorphan Restrictions:
○ RX only in some states
○ Must be 18 years old to purchase in some states
Loperamide
● Used/abused for euphoria (or to avoid/treat opioid withdrawal)
Normal dose: 8mg daily (self-care) up to 16mg daily (RX)
Loperamide Abuse Dose
Abuse dose: 70-100mg daily (reports of up to 1200mg daily)
Loperamide Mechanism of Abuse
○ Weak opioid receptor agonist
○ Requires very high doses
■ Combine with CYP3A4 and CYP2C8 to increase metabolism
■ Combine with pgp-inhibitor to enhance absorption in CNS
Loperamide Risks
○ Cardiac arrest
○ QT prolongation
○ Syncope
○ Cardiac arrhythmias
Loperamide Restrictions
○ September 2019: FDA approved a change limiting packages to a maximum 48mg
First Generation Antihistamines
● Used/abused for euphoria, high energy, positive mood
● Normal dose: 25-50mg every 4 to 6 hours
First Generation Antihistamines Abused Dose
Abuse dose: 3-5x usual dose
75-150mg or 125-250mg every 4-6 hrs
First Generation Antihistamines Mechanism of Abuse
○ Increase dopamine transmission
First Generation Antihistamines Risks
○ Psychosis
○ Changes in heart rhythm
○ Urinary retention
○ CNS depression
First Generation Antihistamines Limitations
None
Tetrahydrozoline
Used/abused for potential to impair another individual
○ CNS depression, muscle weakness, decreased heart rate, and decreased blood pressure
○ Onset in 15-30 minutes and effects diminish within 24 hours
○ Clear and odorless
● Normal dose: 1-2 drops applied to eyes/nose
Tetrahydrozoline Abused Dose
Abuse dose: Ingested orally
Tetrahydrozoline Mechanism of Abuse
○ Lipophilic, so low systemic absorption/ADRs if absorbed after nasal/ocular administration
○ Crosses BBB after ingestion to stimulate alpha-2 receptors and agonize imidazoline-1 receptor
Tetrahydrozoline Restrictions
None
Pseudoephedrine/Ephedrine
Used/abused for stimulant properties
○ Increases heart rate and BP, elevates mood, appetite suppression
● Normal dose: 120mg daily ephedrine
Pseudoephedrine/Ephedrine Abused Dose
1450mg daily ephedrine
Pseudoephedrine/Ephedrine Mechanism of Abuse
○ Sympathomimetics
○ Structurally similar to norepinephrine
Pseudoephedrine/Ephedrine other notes
● ALSO - used to make methamphetamine ● 2005 Combat Methamphetamine Epidemic Act ○ Led to restrictions on pseudoephedrine purchases (daily and monthly)
Laxatives
Used/abused for weight loss
○ Rare in typical population (0.7-5.5%)
○ High rate in population with anorexia/bulimia diagnosis (3-70%)
○ Stimulants are most commonly abused class
Laxatives
○ Used to stimulate bowel movements (purging)
Laxatives
○ Electrolyte imbalance
○ Nutritional deficiencies
Laxatives
○ UK just passed a law limiting sales ■ Retail outlets can sell to 18 and older ■ Pharmacists can sell for use in 12 and older ■ Additional warnings about abuse potential added to labelling
Pharmacist Prevention Tactics
● Keep drugs out of sight ● Question purchase of the medication ● Refusal to sell ● Referral to physician ● Counseling about abuse/misuse potential
Barriers to Pharmacist Prevention
● Challenges in identifying drug related problems
○ Lack of record-keeping with OTC medications
● Lack of widespread tracking or tracking between pharmacies
○ Pseudoephedrine is the exception with the 2005 Combat Methamphetamine Epidemic Act
● Other pharmacist tasks
○ How can technicians help?
The Pharmacist’s Role in Drugs of Misuse
● Drug take-back programs ○ Partner with local sheriff’s office ○ Sell drug disposal products ○ Advertise for local events ● Educate parents and grandparents ● Health literacy
Behind the Counter?
● Drugs that are available only after consultation with a pharmacist
○ No prescription required, but cannot be purchased OTC
● Has been reviewed by the FDA in the past → not currently a formal category
in the U.S.
● Would allow a pharmacist to assess safety, efficacy, appropriateness
● Requires more training for pharmacists and technicians in order to offer the
required assessment
● Proposed medications: codeine products, pseudoephedrine,
diphenhydramine, statins, insulin
Poisoning Epidemiology
● Poisonings are the #1 cause of injury death in the United States and a significant cause of morbidity ● Poisoning tends to be accidental in children ● Poisoning may be accidental or intentional in adults ○ Suicide attempt ○ Substance abuse ○ Medication misuse ● Exposure: ○ Ingestion ○ Topical ○ Inhaled ○ Bites/envenomation
Acetaminophen: One of the leading causes of poisoning from OTC medications
○ Misunderstandings/confusion about use/misuse
○ Accidental overdose from using multiple APAP containing products
○ Intentional misuse - easy access
Acetaminophen: ● Initiatives to improve patient understanding
○ Knowyourdose.org
○ Convert children/infant doses to same concentration to prevent math errors
○ Highlight APAP ingredient on product labels
Poison Control Centers
● 24 hours sources of: ○ Poison information ○ Clinical toxicology consultation ○ Poison prevention education ● Staffed by pharmacists, nurses, physicians, PAs who have additional tox training ● Available for public or healthcare provider consultation ● Contact for assessment/treatment of poisonings OR for educational material
Poison Control Number
1-800-222-1222
Poisoning Stats
● 47.7% of reported cases are in children <6 ● Common non-RX products: ○ Analgesics ○ Cough/cold ○ Topical preparations ○ Vitamins ○ Antihistamines ● 70% of calls to Poison Control Centers can be managed at home
Poison Prevention Packaging Act (1970)
● Purpose: Protect children under 5 from accidental poisoning and death
● Legislated requirement for child-resistant closures (CRC) on possible poisons
● This has reduced the fatalities due to both RX and non-RX exposure
PPPA - OTC Medications
● Mouthwash containing ≥3g ethanol
● Aspirin
● Prescription and controlled medications
PPPA - OTC Medications Products containing:
○ ≥1g acetaminophen ○ ≥1g ibuprofen ○ ≥66mg diphenhydramine base ○ ≥0.045mg loperamide ○ ≥250mg elemental iron ○ ≥250mg naproxen ○ ≥14mg minoxidil
Child Resistant Packaging
● “Designed or constructed to be significantly difficult for children under 5 to
open or obtain a harmful amount of the contents within a reasonable amount
of time”
● 80% of the children tested must not be able to open the package within 10
minutes
● Also tested in adults to make sure it can be opened: 90% of adults must be
able to open within 5 minutes
Exemptions to Child Resistant Packaging
● OTC brands may package one size with non-child resistant packaging
○ Must offer other sizes that are child resistant
● OTC exempted products must label:
○ “This package for households without young children”
○ “Package not child resistant”
● Individuals may request that prescriptions are not placed in child resistant
packaging
Clinical Presentation of Poisoning
● Presentation may vary depending on the drug
● May mimic side effect profile with normal use
○ Ibuprofen → nausea, vomiting, abdominal pain
○ Diphenhydramine → sedation, stimulation, tachycardia, hypertension, dry mouth, dilated pupils
● Others may have more widespread organ effects
○ Aspirin → GI, CNS, metabolic, CV, pulmonary, hematologic
● Signs/symptoms may be delayed
○ ER or enteric coated products may have delayed absorption
○ Delayed gastric emptying or slowed GI motility (diphenhydramine)
○ Metabolism to toxic metabolites (APAP)
Treatment of Poisoning
First step: Determine if the patient has symptoms and if the exposure puts the
patient at risk of toxicity
● Self-care treatment is ONLY appropriate if:
○ Exposure was unintentional
○ Toxicity risk is assessed to be minor
Exclusions for Self-Care Treatment
● Intentional exposure/substance abuse ● Expected suicide or homicide ● Inadvertent exposure with moderate/severe toxicity risk ● Exhibiting life-threatening clinical effects (coma, convulsion, syncope) ○ Call 911 and transport to ER ● Suspected child abuse or elder abuse ● Debilitated or advanced age ● Absent or poor gag reflex ● CNS depression
What can a hospital do?
● Supportive care ○ Keep airway open ○ Fluids ● Prevent absorption ● Increase elimination ● Utilize antidotes
Nonpharmacologic Management
Inhalation exposure
remove from source to fresh air
Nonpharmacologic Management
Skin/mucosal exposure -
irrigation
○ Wash skin with soap and water (pay attention to nail beds and hair)
○ Use water/saline solution to irrigate eyes
Nonpharmacologic Management
Ingestion
○ Administering large amounts of fluids → may cause spontaneous vomiting
○ Some drugs may require fluid dosing
■ Bisphosphonates + esophageal irritation
■ Ibuprofen + renal injury
○ Avoid stimulating the gag reflex manually
Pharmacologic Options: Activated charcoal
○ Adsorbent
○ Controversial use
Pharmacologic Options: Ipecac syrup
Ipecac syrup
○ Emetic
○ Does not improve outcomes → avoid
○ Also not easily purchased
Activated Charcoal Characteristics
● Tasteless, gritty, fine, black, insoluble powder
● Large surface area so it’s a highly effective adsorbent
● As the ratio of activated charcoal to toxin increases, the proportion of bound
toxin increases
Activated Charcoal: Poor adsorbent of:
○ Lithium, potassium (highly ionized) ○ Alcohols ○ Hydrocarbons ○ Mineral acids ○ Heavy metals ○ Cyanide
● Food in GI tract may effect efficacy
Activated Charcoal
● Approved by the FDA for use as emergency antidote for ingested poison
● Home use should only include ONE DOSE
● Usual dose: 1g/kg
Activated Charcoal
Available in different formulations
○ Premixed with water
○ Premixed with water + carboxymethylcellulose
○ Premixed with sorbitol (decreases GI transit time)
Activated Charcoal
Contraindications:
○ GI tract not anatomically or functionally intact
○ Bariatric surgery may require dose adjustments
○ High risk of aspiration
○ If the toxin does not adsorb to charcoal
Activated Charcoal Patient Education
● Products should be shaken vigorously prior to administration
● Some products may have flavoring agents to improve palatability
● Common ADRs:
○ Vomiting (12-20%)
○ Black stool
Activated Charcoal
Considerations
● Works best if administered quickly (works best within one hour)
● It is available as a non-RX drug
● Not typically found in most homes
● Not routinely recommended by a poison center
● Conclusion: it is relatively safe, but it is probably not something that people need or should be recommended to keep around their house due to its controversial place in practice and possibly limited efficacy (especially in selfcare situations)
