Pharmacology Week 7: Endocrine Medications

Comprehensive practice flashcards reviewing all 11 endocrine medications, drug classes, mechanisms, adverse effects, and nursing interventions from Week 7 lecture notes.

Homeostasis (Endocrine System)

The maintenance of internal balance within the body through complex glandular activities that either stimulate or suppress hormone release.

Antidiuretic Hormone (ADH)

Also known as vasopressin, a hormone released by the posterior pituitary gland that promotes water retention by the kidneys.

Diabetes Insipidus

A condition in which the body cannot retain water, resulting in the excretion of massive quantities of dilute urine.

Desmopressin Drug Class

Antidiuretic Hormone, identifiable by the drug stem -pressin.

Desmopressin Indications

Diabetes insipidus (inability to retain water) and hemophilia (an inherited condition where blood fails to clot normally).

Desmopressin Mechanism of Action

Selectively binds $V_2$ receptors in renal collecting ducts to increase water permeability and reabsorption, concentrating urine and decreasing urine output.

$V_2$ Receptors

Water-holding receptors located in the renal collecting ducts of the kidney targeted by desmopressin.

Renal Collecting Ducts

The final tubular segment of the nephron where desmopressin promotes water reabsorption back into systemic circulation.

Desmopressin Administration Routes

Oral ($\text{PO}$), Intranasal, Subcutaneous, Sublingual, and Intravenous ($\text{IV}$).

Desmopressin Adverse Effects

Fluid retention, hyponatremia, vasoconstriction (blood vessel constriction), and seizures.

Hyponatremia (Desmopressin Adverse Effect)

Dangerously low serum sodium resulting from excessive water retention and dilution of the bloodstream.

Desmopressin Contraindications

Vasopressin allergy, coronary artery disease, chronic nephritis, electrolyte imbalances (for oral form), and renal failure.

Desmopressin Cautions

Older adults, cardiovascular disease, hypertension, history of hyponatremia, severe heart failure, and history of thromboembolic events.

Desmopressin Enhancing Drug Interactions

Carbamazepine and chlorpropamide, which enhance the antidiuretic (water-holding) action of desmopressin.

Desmopressin Inhibiting Drug Interactions

Vasopressors and lithium, which diminish the antidiuretic action of desmopressin.

Desmopressin IV Site Complications

Extravasation (medication leakage into surrounding tissue) and local tissue gangrene (tissue death).

Enuresis

Bedwetting in pediatric patients, an indication for desmopressin requiring strict fluid restriction due to high hyponatremia risk.

Desmopressin Water Intoxication Protocol

Holding the medication, checking serum sodium, notifying the healthcare provider, restricting fluids, and initiating seizure precautions.

Triiodothyronine ($T_3$)

The active form of thyroid hormone produced either directly by the thyroid or by peripheral conversion of $T_4$.

Thyroxine ($T_4$)

The primary circulating prohormone secreted by the thyroid gland, converted peripherally to active $T_3$.

Thyroid Stimulating Hormone (TSH)

An anterior pituitary hormone that stimulates the thyroid gland to produce and secrete $T_3$ and $T_4$.

Thyroid Function Test

A laboratory evaluation measuring serum levels of $T_3$, $T_4$, and $TSH$ to assess endocrine function.

Levothyroxine Drug Class

Thyroid Hormone, indicated for the replacement therapy of hypothyroidism.

Levothyroxine Mechanism of Action

Synthetic $T_4$ converted peripherally to active $T_3$ that binds nuclear receptors to regulate gene transcription for metabolic rate, growth, and development.

Levothyroxine Administration Routes

Oral ($\text{PO}$) taken on an empty stomach, and Intravenous ($\text{IV}$) reserved for myxedema coma.

Myxedema Coma

A severe, life-threatening manifestation of hypothyroidism managed with intravenous ($\text{IV}$) levothyroxine.

Thyrotoxicosis

A clinical syndrome resulting from excessive levels of thyroid hormone, which can occur with levothyroxine toxicity or hyperthyroidism.

Levothyroxine Adverse Effects

Thyrotoxicosis, headache, irritability, insomnia, abdominal cramping, diarrhea, tachycardia, arrhythmias, heat intolerance, diaphoresis, and menstrual irregularities.

Levothyroxine Contraindications

Thyrotoxicosis and recent myocardial infarction ($\text{MI}$).

Levothyroxine Absorption-Reducing Substances

Cholestyramine, antacids, iron supplements, calcium supplements, sucralfate, and food.

Four-Hour Separation Rule (Levothyroxine)

The clinical mandate to avoid administering levothyroxine within $4\text{ hours}$ of cholestyramine, antacids, iron, calcium, or sucralfate.

Levothyroxine-Lowering Medications

Antiseizure and antidepressant drugs, including carbamazepine, phenytoin, phenobarbital, and sertraline, which decrease circulating levothyroxine levels.

Warfarin Interaction with Levothyroxine

A drug interaction in which levothyroxine enhances the anticoagulant (blood-thinning) action of warfarin.

Catecholamine Interaction with Levothyroxine

An interaction where levothyroxine augments the cardiac response to catecholamines such as epinephrine.

Thyroxine Form Non-Interchangeability

The teaching instruction that different commercial or generic formulations of thyroxine are not interchangeable.

Cretinism

A pediatric condition of stunted physical growth and intellectual disability caused by untreated congenital hypothyroidism.

Levothyroxine Pregnancy Adjustments

A necessary dosage increase during pregnancy to prevent deficits in fetal neurocognitive development.

Propylthiouracil (PTU) Drug Class

Anti-Thyroid Agent, utilized for suppressing thyroid hormone synthesis.

Propylthiouracil Indications

Hyperthyroidism, thyrotoxic crisis (thyroid storm), and suppression of thyroid hormone production prior to thyroidectomy.

Thyrotoxic Crisis (Thyroid Storm)

A critical emergency characterized by dangerously high thyroid hormone levels, treated with propylthiouracil.

Thyroidectomy Preparation

Preoperative medical management using propylthiouracil to suppress thyroid hormone levels prior to surgical removal of the thyroid.

Propylthiouracil Mechanism of Action

Inhibits thyroid peroxidase, blocks the oxidation of iodide, and decreases the synthesis of $T_3$ and $T_4$.

Thyroid Peroxidase

An enzyme essential for building thyroid hormones by oxidizing iodide, inhibited pharmacologically by propylthiouracil.

Propylthiouracil Administration Schedule

Administered orally ($\text{PO}$) at regular, evenly spaced intervals.

Agranulocytosis

A life-threatening adverse effect of propylthiouracil causing a severe drop in white blood cells, presenting as fever and sore throat.

Hepatotoxicity (Propylthiouracil)

Severe liver injury caused by propylthiouracil, presenting as a significant clinical risk across all age groups.

Aplastic Anemia (Propylthiouracil)

A rare bone marrow failure syndrome where blood cell synthesis halts, listed as an adverse effect of propylthiouracil.

Propylthiouracil Bone Marrow Depression Interaction

Concurrent administration with antineoplastic agents or radiation therapy leading to additive bone marrow suppression.

Phenothiazine Interaction with PTU

Concurrent administration of older antipsychotics with propylthiouracil that increases the risk of agranulocytosis.

Lithium and Potassium Iodide Interaction with PTU

Concurrent use with propylthiouracil that produces additive, increased antithyroid effects.

Glucose Homeostasis

The physiological balancing of energy conservation with energy consumption, utilizing glucose as the primary fuel source.

Counter-Regulatory Hormones

Endogenous hormones that counteract insulin and raise glucose levels: glucagon, epinephrine, cortisol, and growth hormone.

Type 1 Diabetes Mellitus

An autoimmune disorder characterized by destruction of pancreatic beta cells, resulting in absolute insulin deficiency.

Type 2 Diabetes Mellitus

A metabolic disease characterized by cellular insulin resistance paired with progressive pancreatic beta cell dysfunction.

Beta Cells

Pancreatic endocrine cells responsible for the synthesis and secretion of endogenous insulin.

Hypoglycemia

Abnormally low blood glucose concentration, presenting with symptoms like shaking, diaphoresis, and confusion.

Beta-Blocker Masking Effect

The pharmacologic suppression of adrenergic hypoglycemia signs (specifically masking tachycardia) by beta blockers.

Oral Hypoglycemia Treatment Protocol

Providing $4\text{ oz}$ of orange juice, $2\text{ to }3\text{ tsp}$ of sugar, honey in water, or glucose tablets, rechecking in $15\text{ to }20\text{ minutes}$.

Unconscious Hypoglycemia Management

The parenteral administration of glucagon indicated when a hypoglycemic client cannot swallow safely or is unconscious.

Insulin Drug Class

Insulin, indicated for Type 1 Diabetes, Type 2 Diabetes, and gestational diabetes.

Insulin Mechanism of Action

Binds specific cellular insulin receptors to promote cellular uptake of glucose and regulate fuel metabolism.

Rapid-Acting Insulin

Insulin lispro (Humalog), insulin aspart (Novolog), and insulin glulisine (Apidra), which carry the highest risk for hypoglycemia.

Rapid-Acting Insulin Pharmacokinetics

Onset of $5\text{ to }30\text{ min}$, peak of $30\text{ to }90\text{ min}$, and duration of $3\text{ to }5\text{ hrs}$.

Short-Acting Insulin (Regular Insulin)

Insulin formulations (Humulin R, Novolin R); the only form authorized for intravenous ($\text{IV}$) use.

Short-Acting Insulin Pharmacokinetics

Onset of $30\text{ to }60\text{ min}$, peak of $2\text{ to }4\text{ hrs}$, and duration of $5\text{ to }7\text{ hrs}$.

Diabetic Ketoacidosis ($\text{DKA}$) Insulin Route

Intravenous ($\text{IV}$) infusion of regular insulin to treat severe hyperglycemia and acidosis.

Intermediate-Acting Insulin (NPH)

A cloudy insulin suspension (Humulin N, Novolin N) administered subcutaneously and never given intravenously.

Intermediate-Acting Insulin Pharmacokinetics

Onset of $1\text{ to }2\text{ hrs}$, peak of $4\text{ to }12\text{ hrs}$, and duration of $18\text{ to }24\text{ hrs}$.

Long-Acting Insulin

Insulin glargine (Lantus) and insulin detemir (Levemir), which provide basal coverage with no peak and lowest hypoglycemia risk.

Long-Acting Insulin Pharmacokinetics

Onset of $1\text{ to }2\text{ hrs}$, peak: none, and duration of $24+\text{ hrs}$.

Lantus ('Lonely Insulin') Mixing Restriction

The directive stating that insulin glargine cannot be mixed in a syringe with any other insulin type.

Lipodystrophy and Lipohypertrophy

Localized subcutaneous fat loss or fatty lumps caused by repeated injections into the same anatomical site.

Insulin Hypoglycemic Synergists

Sulfonylureas, meglitinides, beta blockers, salicylates (aspirin), and alcohol, which enhance insulin's sugar-lowering effect.

Insulin Antagonistic Drugs

Thiazide and loop diuretics, sympathomimetics, thyroid hormones, and glucocorticoids, which increase blood glucose levels.

Insulin-Induced Hypokalemia

An intracellular potassium shift driven by insulin, necessitating ongoing potassium level and electrocardiogram ($\text{ECG}$) monitoring.

Cloudy Insulin Resuspension Technique

Gently rolling the suspension vial between the palms to disperse particles before drawing up the medication.

'Clear Before Cloudy' Principle

The procedural order when mixing insulins: regular insulin (clear) is drawn up into the syringe before NPH (cloudy).

Insulin Storage Guidelines

Refrigerating unopened vials; opened vials remain stable and good for use at room temperature for $1\text{ month}$.

Insulin Dose Adjustment Triggers

Caloric intake variations, systemic infection, exercise, emotional stress, adolescent growth spurts, and pregnancy.

Insulin Injection Temperature Rule

The clinical recommendation instructing patients never to inject cold insulin directly from refrigeration.

Puberty Resistance to Insulin

A developmental consideration where pubertal growth surges induce temporary physiologic resistance to insulin.

Glyburide Drug Class

Sulfonylureas, an oral antidiabetic drug class.

Glyburide Indication

Type 2 Diabetes Mellitus.

Glyburide Mechanism of Action

Stimulates endogenous insulin release from functioning pancreatic beta cells.

Glyburide Route of Administration

Oral ($\text{PO}$).

Glyburide Gastrointestinal Adverse Effects

Anorexia (loss of appetite), nausea, vomiting, heartburn, and diarrhea.

Hemolytic Anemia (Glyburide Adverse Effect)

Pathological destruction of red blood cells requiring complete blood count ($\text{CBC}$) monitoring during therapy.

Disulfiram-Like Reaction (Glyburide)

An unpleasant adverse reaction (nausea, palpitations, flushing) triggered when alcohol is consumed during glyburide therapy.

Glyburide Contraindications

Pregnancy and diabetic ketoacidosis ($\text{DKA}$).

Glyburide Hypoglycemia Potentiators

Sulfonamide antibiotics, NSAIDs, oral anticoagulants, salicylates, MAOIs, and cimetidine.

Thiazide Diuretics Interaction with Glyburide

A drug interaction where mild water pills (thiazides) elevate glucose and counteract glyburide's hypoglycemic effect.

Glyburide Blood Glucose Monitoring Interval

Checking blood glucose every $15\text{ to }20\text{ minutes}$ during an acute hypoglycemic episode.

Metformin Drug Class

Biguanides, identifiable by the drug stem -formin.

Metformin Indication

Type 2 Diabetes Mellitus.

Metformin Hepatic Mechanism

Decreases hepatic gluconeogenesis, reducing the synthesis of new glucose by the liver.

Metformin Peripheral Mechanism

Increases peripheral insulin sensitivity and promotes glucose uptake in peripheral body tissues.

Metformin Intestinal Mechanism

Decreases the absorption of glucose from the gastrointestinal tract.

Metformin Route of Administration

Oral ($\text{PO}$).

Lactic Acidosis (Metformin Adverse Effect)

A rare but potentially fatal buildup of blood lactate, presenting with weakness, fatigue, lethargy, and hyperventilation.

Dysgeusia (Metformin Adverse Effect)

An altered sense of taste characterized specifically by a persistent metallic taste.