Basics of Pharmacology for the MSLP Student
Importance of Pharmacological Knowledge for Speech-Language Pathologists
Crucial Role in Monitoring: Speech-language pathologists (SLPs) are vital in monitoring for potential negative side effects of medications and drug interactions. This includes noting clinical observations and consulting with nursing staff and physicians regarding these issues.
Interdisciplinary Collaboration: SLP awareness is critical for success in clinical settings. SLPs should work together with nursing staff and physicians to identify, track, and document side effects, particularly when they impact therapy outcomes.
Risks in Elderly Populations: Elderly patients are at an increased risk due to:
Taking multiple medications (polypharmacy).
Age-related physiological changes making the body more susceptible to side effects.
Definitions and Foundations of Pharmacology
Pharmacology: The study of the biological effects of chemicals.
Drugs: Chemicals introduced into the body to cause some sort of change.
Pharmacotherapeutics (Clinical Pharmacology): The specific use of drugs to prevent and treat disease.
Inclusions: Drugs include prescription medications, over-the-counter (OTC) medications, vitamins, and herbal supplements.
Sources of Drugs:
Plants: Active chemicals found in plants. Examples include the poppy for morphine and foxglove for digitalis.
Fungus: Active compounds such as penicillin and ergotamine.
Animal Products: Used to replace human chemicals not produced due to disease or genetics; for example, porcine insulin.
Inorganic Compounds: Salts of various elements that have therapeutic effects, such as lithium for mood disorders and antacids for GI issues.
Synthetic Sources: Produced through genetic engineering or using bacteria, such as modern insulin, monoclonal antibodies, and vaccines.
Historical Regulation and Federal Legislation
19th and Early 20th Centuries: Chemical access was unregulated; ingredients were often unlisted, and labels frequently contained false or outlandish claims.
Major Federal Legislation:
1906 - Pure Food and Drug Act: Prevented marketing of adulterated drugs; required labeling to eliminate false or misleading claims.
1938 - Federal Food, Drug and Cosmetic Act: Mandated tests for drug toxicity, provided for drug recalls, established procedures for introducing new drugs, and gave the FDA enforcement power.
1951 - Durham-Humphrey Amendment: Tightened control of certain drugs; specified that certain drugs must be labeled "may not be distributed without a prescription."
1962 - Kefauver-Harris Act: Tightened control over drug quality, gave the FDA regulatory power over drug investigations, and required that both efficacy and safety be established.
1970 - Controlled Substances Act: Defined drug abuse and classified drugs based on their potential for abuse; provided strict controls over distribution, storage, and use.
1983 - Orphan Drug Act: Provided incentives for developing drugs for rare diseases.
Safety, Regulation, and Controlled Substances
FDA Approval Process: Designed to ensure safety and reliability. Includes a series of tests to determine therapeutic and toxic effects. This process can take 5–6 years.
Scope of FDA Regulation: Regulates prescription and OTC medications. Dietary and herbal supplements are NOT regulated by the FDA.
Controlled Substance Schedules:
CI: Highest abuse potential, no accepted medical use (e.g., heroin, LSD).
CII: High abuse and dependence potential (e.g., narcotics, amphetamines).
CIII: Less abuse potential than CII (e.g., certain sedatives, non-amphetamine stimulants).
CIV: Limited abuse potential (e.g., certain anti-anxiety medications).
CV: Lowest abuse potential of the regulated drugs; contains small amounts of narcotics (e.g., codeine in antitussives or antidiarrheals).
Over-the-Counter (OTC) and Herbal Supplements
OTC Drugs:
Available without prescription for self-treatment.
Historical Origin: Some were previously prescription drugs (e.g., loratidine/Claritin), while others were "grandfathered" and never underwent full modern FDA testing.
Risks: Failure to follow directions can lead to overdose or toxicity.
Herbal Supplements:
Classified as dietary supplements, not drugs.
No regulation by any industry; active ingredients are not FDA-tested, and incidental ingredients may be unknown.
Complications: May mask signs and symptoms of underlying disease, or cause dangerous drug-drug interactions.
Pharmacodynamics and Pharmacokinetics
Pharmacodynamics: Defined as what the drug does to the body. It deals with interactions between living organisms and foreign chemicals.
Drug Actions:
Replace/substitute missing chemicals (e.g., Insulin replaces deficient hormones).
Increase/stimulate certain cellular activities (e.g., monoamine oxidase inhibitors (MAOIs) stop the breakdown of norepinephrine).
Depress/slow cellular activities (e.g., beta-adrenergic blockers depress sympathetic nervous system response).
Interfere with foreign cell functioning (e.g., antibiotics inhibiting bacteria cell wall formation).
Pharmacokinetics: Defined as what the body does to the drug. This includes four phases: absorption, distribution, metabolism, and excretion.
Absorption: The movement of a drug from introduction into the body until it reaches circulating fluids and tissues.
Faster Routes: Intravenous, sublingual, inhalation (seconds to minutes).
Slower Routes: Oral, intramuscular injection, subcutaneous injection (minutes to hours).
First Pass Effect: Oral medications are metabolized by the liver before entering the systemic circulation, which reduces the drug’s strength.
Distribution: Movement to body tissues impacted by blood flow, solubility, and protein binding.
Lipid-soluble drugs cross the blood-brain barrier more easily than water-soluble drugs.
Drug portion bound to protein is inactive; only free/unbound portions are active.
Metabolism (Biotransformation): Breaks down medications. The liver is the most important site for metabolism.
Excretion: Removal of drugs from the body. The kidneys play the most important role, though excretion also occurs through skin, lungs, intestines, and exocrine glands.
Factors Influencing Drug Effect
Weight: Dosages may be adjusted based on ideal body weight to avoid toxicity.
Age:
Pediatrics: Doses based on weight () or surface area ().
Geriatrics: Increased toxicity/adverse effects due to physiological changes; often require lower starting doses.
Pathological Factors: Vascular changes, GI dysfunction, and liver/kidney function.
Genetic Factors: Can alter enzyme systems involved in metabolism.
Psychological Factors: Placebo effect and personality affecting compliance.
Drug Tolerance: Increased dosage needed after prolonged use.
Cumulative Effect: Occurs if doses are taken too close together or if excretion is impaired.
Interactions: Antagonistic (cancel each other out) or Synergistic (work better together).
Specific Drug and Food Interactions
Potency Changes:
Coumadin + Aspirin = Excessive bleeding.
Sedatives + Alcohol = Excessive sedation.
Food Interactions:
Grapefruit juice: Inhibits HMG-CoA reductase inhibitors (e.g., atorvastatin) or calcium channel blockers (e.g., amlodipine), leading to toxic drug levels.
Vitamin K-rich foods: Antagonize anticoagulants like Coumadin.
Tyramine (aged cheese, cured meats): Can cause fatal hypertension in patients taking MAOIs such as phenelzine.
Undesired Drug Effects
Side Effect: An expected but unwanted effect (e.g., dry mouth).
Adverse Effect: A harmful or dangerous reaction (e.g., allergic reaction, severe dizziness) that can lead to hospitalization or death.
Hypersensitivity Reaction: Anaphylactic allergic reactions (hives, wheezing) are life-threatening emergencies.
Toxicity: Can be hepatic (liver), renal (kidney), or sensory/neurological.
Sensory and Neurological Effects
Ototoxicity/Auditory Damage: Tinnitus, loss of balance, or hearing loss. Caused by antibiotics (gentamicin), cancer drugs (cisplatin), diuretics (furosemide/Lasix), and NSAIDs (aspirin, ibuprofen).
CNS Effects: Confusion, dizziness, sedation, or stimulation. Caused by narcotics (morphine), anti-anxiety meds (lorazepam), muscle relaxants, and blood pressure meds (lisinopril, losartan).
Note: Lisinopril is an ACE inhibitor and can also cause a dry cough.
Anticholinergic Effects: Dry mouth (xerostomia), urinary retention, blurred vision. Caused by antihistamines, antidepressants, and antipsychotics.
Extrapyramidal Symptoms (EPS) & Parkinson-like Syndrome: Muscle tremors, impaired swallowing, gait changes. Caused by neuroleptics/antipsychotics.
Special Populations: Pediatrics
Prevalence: 20% of children/adolescents take prescription drugs (e.g., Bronchodilators/albuterol, stimulants/methylphenidate, antidepressants/fluoxetine).
Comorbidities: 40% of children with speech/language disorders have serious comorbidities (ASD, ID) that may require psychiatric medications.
Side Effects: Nervousness, anxiety, tremor, blurring vision, dry mouth, and possible suicidal ideation with antidepressants.
Special Populations: Geriatrics
Prevalence: 87% take at least one prescription drug; 36% take 5 or more (polypharmacy).
Physiological Changes:
Absorption: Less acidic gastric pH, slowed gastric emptying/peristalsis.
Distribution: Decreased lean body mass, increased fat, reduced body water, fewer protein-binding sites.
Metabolism: Decreased liver blood flow and liver mass.
Excretion: Decreased renal filtration rate and fewer nephrons.
Common Meds: Antidepressants, antipsychotics, diuretics, antiarrhythmics, antihypertensives, statins, and proton pump inhibitors.
Drugs That May Cause Dysphagia
Impaired Muscle Function: Antipsychotics/neuroleptics block dopamine, leading to dystonia, akathisia, bradykinesia, tremor, and tardive dyskinesia.
Specific Drugs: Haloperidol, Clozapine (Clozaril), Risperidone (Risperdal), Olanzapine (Zyprexa), Quetiapine (Seroquel), Aripiprazole (Abilify), Paliperidone (Invega).
Xerostomia (Dry Mouth): Limits bolus formation and transport.
Specific Drugs: Antihistamines (diphenhydramine/Benadryl), blood pressure meds (amlodipine, metoprolol), opiates (MS Contin, hydrocodone), and anticholinergics.
Drug-Induced Esophageal Injury (DIEI): Caustic damage to mucosa.
Specific Drugs: NSAIDs, antibiotics, bisphosphonates (alendronate/Fosamax), Vitamin C, potassium chloride, and ferrous sulfate.
Prevention: Take with a full glass (/8 oz) of water, sit upright for 30 minutes after taking.
Case Study: Sara
Patient Profile: 81-year-old female, history of CVA (stroke), right side weakness.
Medications:
Alendronate (Fosamax) for osteoporosis.
Lisinopril (Prinivil) for high blood pressure.
Aripiprazole (Abilify) for depression/aggression.
Gentamicin (Garamycin) for UTI.
Clinical Implications:
Alendronate: Risk of esophageal injury; requires upright positioning.
Lisinopril: Side effects like dizziness or dry cough may affect speech/therapy.
Aripiprazole: May cause EPS, tremors, or impaired swallowing (dysphagia).
Gentamicin: Potential for ototoxicity (hearing/balance issues).
Questions & Discussion
Question: What impact could side effects like nervousness, dizziness, or dry mouth have on therapy?
Answer: These side effects can directly and indirectly impact a client’s ability to swallow, communicate, and participate in SLP therapy. Understanding these effects allows the SLP to understand the client more fully and ensure safe, effective care.