💧 Module 11 · Diuretics, IV Fluids & Poisoning

11 drugs · 11 concepts · tested on Exam 6

💡 The big idea

Three related fluid topics. Diuretics are sorted by WHERE in the nephron they act, which decides how strong they are and which electrolyte they waste. IV fluids are sorted by tonicity, which decides which direction water moves relative to the cell. Antidotes are simple pairs — the only work is knowing which poison goes with which reversal agent and how fast you have to act.

🧠 How to think about this module

Walk the nephron and strength follows: loop diuretics act on the loop of Henle (strongest), thiazides on the distal tubule (moderate), potassium-sparing on the collecting duct (weakest). Osmotics pull water from everywhere.
The potassium answer drives everything: loops and thiazides WASTE potassium; spironolactone and eplerenone KEEP it.
Tonicity is about the cell. Hypotonic fluid drives water INTO cells and swells them. Hypertonic pulls water OUT and shrinks them. Isotonic stays in the vascular space.
Every antidote question is a pairing question. Learn the pairs cold — they are free points.
For any diuretic the nursing assessment is the same four things: daily weight, intake and output, blood pressure with orthostatics, and electrolytes.

🏷️ The whole module in 10 classes

Learn these groups and the drug list stops being 11 separate names.

Class	What it does	Examples	What gets tested
Loop diuretics	Block sodium reabsorption in the ascending loop of Henle. Strongest diuretic and still works when kidney function is poor.	furosemide, bumetanide, torsemide	Hypokalemia, hypotension, hypovolemia, and ototoxicity when pushed too fast — give IV furosemide slowly, no faster than about 20 mg per minute. Daily weight is the best measure of effect: 1 kg equals about 1 L of fluid.
Thiazide diuretics	Moderate diuresis at the distal tubule; first-line for uncomplicated hypertension.	hydrochlorothiazide, chlorthalidone, metolazone	Hypokalemia, hyponatremia, hyperglycemia, and hyperuricemia (can trigger a gout flare). Sulfa-based. Largely ineffective when GFR is low — that is when you switch to a loop.
Potassium-sparing diuretics / aldosterone antagonists	Weak diuresis, but potassium is retained.	spironolactone, eplerenone, triamterene, amiloride	Hyperkalemia — no salt substitutes (they are potassium chloride) and no potassium supplements. Spironolactone causes gynecomastia and menstrual irregularity.
Osmotic diuretics	Pull water out of tissue into the vascular space, then out through the urine.	mannitol	Used for cerebral edema and raised intracranial pressure and for acute glaucoma. Use a filter needle or in-line filter and inspect for crystals. It EXPANDS volume first, so it can precipitate pulmonary edema and heart failure. Monitor serum osmolality, electrolytes, and neuro status.
Carbonic anhydrase inhibitors	Weak diuretic; mostly used to lower intraocular pressure and for altitude sickness.	acetazolamide, dorzolamide (ophthalmic)	Metabolic acidosis, hypokalemia, and paresthesias. Sulfa-based — ask about sulfa allergy.
Isotonic IV fluids	Stay in the vascular space. Volume replacement and resuscitation.	0.9% sodium chloride (normal saline), lactated Ringer's, D5W (in the bag)	Fluid overload: crackles, jugular venous distension, bounding pulse, sudden weight gain, shortness of breath. Large volumes of normal saline cause hyperchloremic metabolic acidosis; lactated Ringer's is avoided in liver failure and hyperkalemia.
Hypotonic IV fluids	Move water INTO cells to rehydrate them.	0.45% sodium chloride, 0.225% sodium chloride	NEVER for increased intracranial pressure, head injury, stroke, or burns — cellular swelling makes those worse. Monitor sodium and neuro status; infuse slowly.
Hypertonic IV fluids and concentrates	Pull water OUT of cells into the vascular space.	3% sodium chloride, dextrose 50%, 25% albumin, dextran, D5NS	3% saline requires a pump, frequent sodium levels, and usually central access. Correcting sodium too quickly causes osmotic demyelination. Watch for fluid overload — these expand volume fast.
Electrolyte replacement	Replaces a specific electrolyte deficit.	potassium chloride, magnesium sulfate, calcium gluconate, sodium bicarbonate	Potassium chloride is NEVER given IV push — it causes cardiac arrest. Always diluted, always on a pump; peripheral infusion generally does not exceed 10 mEq/hr and central 20 mEq/hr with cardiac monitoring. Confirm adequate urine output before giving. Oral potassium goes with food and a full glass of water. For acute HYPERkalemia the emergency combination is IV calcium gluconate to protect the heart plus regular insulin with dextrose to drive potassium into the cells — insulin here is not being given for glucose.
Antidotes and reversal agents	Reverse or neutralize a specific poison.	acetylcysteine (acetaminophen), naloxone (opioids), flumazenil (benzodiazepines), glucagon (beta blocker overdose and hypoglycemia), sodium bicarbonate (TCA overdose, severe acidosis, urine alkalinization), ammonium chloride (acidifier for metabolic alkalosis and to acidify urine), dimercaprol and edetate calcium disodium (heavy metals), activated charcoal (recent ingestion)	Acetylcysteine works best when started within 8 to 10 hours of the acetaminophen ingestion — do not wait for symptoms, because the client looks fine while the liver is dying. Flumazenil can precipitate seizures in a chronic benzodiazepine user or a mixed overdose.

⚖️ Tonicity — which way does the water go?

Hypotonic	Isotonic	Hypertonic
0.45% NaCl, 0.225% NaCl	0.9% NaCl, lactated Ringer's, D5W in the bag	3% NaCl, D50, 25% albumin, D5NS, D5LR
Water moves INTO the cell — cells swell	Water stays put — expands the vascular space	Water moves OUT of the cell — cells shrink
For cellular dehydration, hypernatremia, DKA after initial resuscitation	For hypovolemia, hemorrhage, shock, and surgery	For severe symptomatic hyponatremia and cerebral edema
NEVER with increased ICP, head injury, stroke, or burns	Watch for fluid overload in heart failure and kidney disease	Pump required, frequent sodium checks, usually central access

🚨 Red flags DANGER

Potassium chloride is never given IV push and never undiluted. Confirm the dilution, the pump, and adequate urine output before hanging it.
Hypotonic fluid ordered for a head-injured client or one with increased ICP: question the order. It worsens cerebral edema.
A client on a loop diuretic with muscle cramps, weakness, and flattened T waves or U waves: check the potassium. Hypokalemia plus digoxin on board is a lethal combination.
Acetaminophen overdose: give acetylcysteine early, ideally within 8 hours. A client who looks well at hour 6 is still in danger — hepatic failure arrives days later.
Flumazenil in a chronic benzodiazepine user or an unknown mixed overdose can cause status epilepticus. Support the airway first and reverse selectively.

🧵 Exam traps ⭐ HIGH YIELD

Furosemide wastes potassium; spironolactone saves it. The 'eat bananas and oranges' teaching belongs to loops and thiazides only, and is actively harmful advice for a client on spironolactone.
D5W is isotonic in the bag but acts hypotonic in the body once the dextrose is metabolized — which is why it is not a resuscitation fluid and not used in head injury.
Mannitol is a diuretic that first EXPANDS the vascular volume. In a client with heart failure that is a hazard, not a benefit.
Thiazides, loops, acetazolamide, sulfonylureas, and celecoxib all carry a sulfonamide group. Ask about sulfa allergy.
Naloxone reverses opioids and flumazenil reverses benzodiazepines. Neither reverses alcohol, barbiturates, or a stimulant. Match the receptor.
Daily weight, not intake and output, is the most reliable measure of fluid status — 1 kg equals about 1 L. Same scale, same time, same clothing.

🧠 Ways to remember it

Nephron order is strength order: Loop (strongest), Thiazide (middle), Potassium-sparing (weakest).
Loops Lose potassium. Spironolactone Spares it.
hypOtonic = cells blOw up. hypERtonic = cells shrivel (water Exits).
Potassium IV push Kills. Never push K.
Antidote pairs: acetaminophen-acetylcysteine, opioid-naloxone, benzo-flumazenil, beta blocker-glucagon, heparin-protamine, warfarin-vitamin K, magnesium-calcium gluconate.

🧠 The concepts 11

What are the different pharmaceutical classifications of diuretics? Give examples of drugs in each class.⭐ HIGH YIELD

Five classes: LOOP (furosemide, bumetanide, torsemide), THIAZIDE (hydrochlorothiazide, chlorthalidone, metolazone), POTASSIUM-SPARING (spironolactone, eplerenone, amiloride, triamterene), OSMOTIC (mannitol), and CARBONIC ANHYDRASE INHIBITORS (acetazolamide). They differ by where in the nephron they act, which determines potency and which electrolytes are lost.

LOOP diuretics are the most POTENT. They block reabsorption in the loop of Henle and cause loss of sodium, potassium, calcium, and magnesium. Onset within 1 hour orally, peak in the first or second hour, duration 6 to 8 hours. Used for acute fluid overload and pulmonary edema, and they still work when the GFR is low. OTOTOXIC if pushed too fast IV - give furosemide no faster than 20 mg/min. Sulfa-allergic patients may need ethacrynic acid.
THIAZIDES act near the distal tubule and are NOT effective for immediate diuresis - they are maintenance antihypertensives. They lose sodium and potassium but RETAIN CALCIUM (useful in osteoporosis, bad in hypercalcemia). They stop working when the GFR falls below about 30. They raise uric acid (gout), glucose, and lipids, and cause photosensitivity. HCTZ plus large amounts of licorice causes hyperkalemia per the textbook.
POTASSIUM-SPARING agents are weak diuretics used mainly for their potassium-sparing and, for spironolactone, mortality benefit in heart failure. HYPERKALEMIA is the danger: no salt substitutes, no potassium supplements, and caution with ACE inhibitors and ARBs. Spironolactone also causes GYNECOMASTIA, menstrual irregularity, and hirsutism because it blocks androgen receptors; eplerenone does not.
MANNITOL is an osmotic diuretic that pulls fluid out of cells and tissues by raising the osmotic pressure of the glomerular filtrate. It is used for increased INTRACRANIAL PRESSURE and cerebral edema, and for increased intraocular pressure. Give through an in-line FILTER, inspect for crystals (warm the bottle if crystallized), monitor serum osmolality and neuro status, and expect a transient rise in intravascular volume that can precipitate heart failure.
ACETAZOLAMIDE is weak as a diuretic and causes metabolic ACIDOSIS with potassium loss. It is used for glaucoma, altitude sickness, and some seizure disorders.
FOR ALL DIURETICS: daily weights at the same time on the same scale (1 kg equals about 1 liter), strict intake and output, monitor electrolytes and renal function, monitor for orthostatic hypotension and falls, and GIVE IN THE MORNING so the patient can sleep. Report weight gain over 3 pounds in a day. Loops and thiazides cause HYPOkalemia (encourage potassium-rich foods: bananas, oranges, potatoes, spinach). Potassium-sparing agents cause HYPERkalemia. Both matter enormously if the patient is also on digoxin, because hypokalemia potentiates digoxin toxicity.

Class	Site of action	Examples	Key point
Loop	Loop of Henle	furosemide, bumetanide, torsemide, ethacrynic acid	MOST POTENT; loses K+, Ca++, Mg++; OTOTOXIC if pushed fast
Thiazide	Distal tubule	hydrochlorothiazide, chlorthalidone, metolazone	Maintenance HTN, not for acute overload; RETAINS calcium; raises uric acid and glucose
Potassium-sparing	Collecting duct	spironolactone, eplerenone, amiloride, triamterene	HYPERKALEMIA risk; spironolactone causes gynecomastia; HF mortality benefit
Osmotic	Glomerulus / proximal tubule	mannitol	Increased ICP and IOP; use a FILTER; watch for crystals and fluid overload
Carbonic anhydrase inhibitor	Proximal tubule	acetazolamide	Glaucoma, altitude sickness; causes metabolic ACIDOSIS

Loops LOSE everything. Thiazides KEEP calcium. Spironolactone KEEPS potassium. Mannitol pulls water off the BRAIN.

What are the indications for hypotonic, isotonic, and hypertonic solutions?⭐ HIGH YIELD

ISOTONIC fluids stay in the vessels and expand blood volume - use for dehydration, hemorrhage, shock, and blood administration. HYPOTONIC fluids move water INTO cells - use for cellular dehydration, hypernatremia, and DKA after initial resuscitation. HYPERTONIC fluids pull water OUT of cells into the vessels - use for severe symptomatic hyponatremia and cerebral edema.

ISOTONIC (same osmolality as plasma, about 275 to 295 mOsm/L): no fluid shift. Indications include hypovolemia, hemorrhage, vomiting and diarrhea, burns, shock, and as the only fluid compatible with blood products (0.9% NaCl). RISK: fluid overload, so monitor lungs, edema, jugular veins, and daily weights, especially in heart failure and renal failure.
HYPOTONIC (lower osmolality): water leaves the vessels and enters cells, rehydrating them. Indications: hypernatremia, cellular dehydration, DKA maintenance after the initial isotonic bolus, and as a maintenance fluid. DANGER: it makes cells swell, so it is CONTRAINDICATED in increased intracranial pressure, head trauma, stroke, and neurosurgery (worsens cerebral edema), and in burns, trauma, and hypovolemia, where it can worsen hypotension and cause vascular collapse.
HYPERTONIC (higher osmolality): water is pulled out of cells into the vascular space. Indications: severe symptomatic hyponatremia, cerebral edema and increased ICP, and third-spacing with hypovolemia. DANGER: fluid overload and pulmonary edema, cell shrinkage and dehydration, and phlebitis. Give slowly, on a PUMP, usually through a CENTRAL line, with frequent neuro checks and serum sodium.
THE SODIUM CORRECTION RULE: correct sodium NO FASTER than about 8 to 10 mEq/L in 24 hours. Correcting too fast causes OSMOTIC DEMYELINATION SYNDROME (central pontine myelinolysis), which is permanent and devastating.
For every IV fluid: assess lung sounds, edema, jugular venous distention, daily weight, strict intake and output, electrolytes, and mental status. Use an infusion pump for hypertonic solutions and for anyone at risk of overload.
The direction of water movement is the whole concept: water always moves TOWARD the higher concentration of solute. Hypotonic fluid is dilute, so water leaves it and goes into the cell. Hypertonic fluid is concentrated, so it pulls water out of the cell.

Tonicity	Water moves	Use for	Do NOT use in
ISOTONIC	Stays in the vascular space	Hypovolemia, hemorrhage, shock, vomiting/diarrhea, burns, blood administration (NS)	Heart failure, renal failure, cerebral edema (overload risk)
HYPOTONIC	Out of vessels INTO cells	Hypernatremia, cellular dehydration, DKA maintenance, maintenance fluid	Increased ICP, head trauma, stroke, burns, trauma, hypovolemia
HYPERTONIC	Out of cells INTO vessels	Severe symptomatic hyponatremia, cerebral edema/increased ICP, third-spacing	Dehydration, heart or renal failure; give slowly on a pump, central line preferred

HypOtonic goes Out to the cells (they swell). HyperTonic pulls water back To the vessels (cells shrink). Isotonic stays put.

Give examples of IV fluids that are hypotonic, isotonic, and hypertonic.⭐ HIGH YIELD

HYPOTONIC: 0.45% NaCl (half normal saline), 0.33% NaCl, 0.225% NaCl, and D5W once the dextrose is metabolized. ISOTONIC: 0.9% NaCl (normal saline), lactated Ringer's, and D5W in the bag. HYPERTONIC: 3% and 5% NaCl, D10W, D5 in 0.45% NaCl, D5 in 0.9% NaCl, D5 in lactated Ringer's, and D50W.

D5W IS THE TRICK QUESTION. It is ISOTONIC IN THE BAG (about 252 mOsm/L) but becomes HYPOTONIC IN THE BODY as soon as the dextrose is metabolized, leaving free water. That is why it is dangerous in head injury and increased ICP.
Any 'D5 plus something isotonic' is HYPERTONIC: D5NS, D5 half-NS, and D5LR. Adding dextrose to an already isotonic solution pushes the osmolality above plasma.
LACTATED RINGER'S is isotonic and contains sodium, chloride, potassium, calcium, and lactate (which the liver converts to bicarbonate). It is preferred for burns and large-volume resuscitation. Avoid in liver failure (cannot metabolize lactate), in hyperkalemia (it contains potassium), and NEVER with blood products (the calcium clots the line).
0.9% NORMAL SALINE is the only fluid that may be given with blood. Large volumes cause hyperchloremic metabolic acidosis.
3% NaCl is the hypertonic saline used for symptomatic hyponatremia and cerebral edema. It requires a pump, frequent sodium checks, and usually a central line and an ICU setting.
Memory anchor: the number tells you the tonicity for saline. Below 0.9% is hypotonic, exactly 0.9% is isotonic, above 0.9% is hypertonic. For dextrose, 5% alone is isotonic in the bag, and anything higher (10%, 50%) is hypertonic.

HYPOTONIC	ISOTONIC	HYPERTONIC
0.45% NaCl (half NS)	0.9% NaCl (NS)	3% NaCl and 5% NaCl
0.33% NaCl	Lactated Ringer's	D10W, D50W
0.225% NaCl (quarter NS)	D5W (in the bag only)	D5 in 0.45% NaCl
D5W once dextrose is metabolized	Ringer's solution, Plasma-Lyte	D5 in 0.9% NaCl, D5 in LR

Under 0.9 is hypo, 0.9 is iso, over 0.9 is hyper. D5W is iso in the bag and hypo in the body.

Dextran 40🚨 DANGER

Dextran 40 is a low-molecular-weight COLLOID plasma volume EXPANDER. It stays in the vascular space and pulls interstitial fluid in with it, so it expands blood volume by MORE than the volume infused. Used for hypovolemic shock and to improve microcirculation and prevent thrombosis.

IT INTERFERES WITH BLOOD TYPING AND CROSSMATCHING. DRAW THE TYPE AND CROSSMATCH SPECIMEN BEFORE STARTING THE INFUSION. This is the number one nursing point.
It has ANTIPLATELET and antithrombotic effects: it coats platelets and reduces blood viscosity, so it INCREASES BLEEDING RISK. Monitor for bleeding, and avoid in thrombocytopenia and active hemorrhage.
ANAPHYLAXIS can occur, sometimes with the first few milliliters. Stay with the patient and infuse the first 5 to 10 minutes slowly with close observation. Keep emergency equipment available.
RENAL FAILURE is a real risk, especially in dehydrated patients: dextran is filtered by the kidney and can cause osmotic nephrosis and tubular obstruction. Ensure adequate hydration, monitor urine output hourly, and monitor BUN and creatinine.
Because it is a volume expander, it can cause FLUID OVERLOAD and pulmonary edema. Monitor lung sounds, jugular veins, and daily weights. Contraindicated in severe heart failure and severe renal disease with oliguria or anuria.
Dextran 70 is the higher-molecular-weight version used mainly for volume expansion; dextran 40 is preferred when improving microcirculatory flow is the goal. Colloids (dextran, albumin, hetastarch) stay in the vessels and expand volume more efficiently than crystalloids (NS, LR), but they cost more and carry these specific risks.

Dextran pulls fluid IN, but draw the crossmatch FIRST and watch for bleeding and kidneys.

Dextrose in water 5%🚨 DANGER

Dextrose 5% in water (D5W) is ISOTONIC IN THE BAG but functionally HYPOTONIC IN THE BODY, because the dextrose is metabolized within minutes leaving free water that shifts into cells. It provides free water and about 170 calories per liter, and is used as a maintenance fluid, a drug diluent, and to treat hypernatremia and free water deficit.

DO NOT GIVE D5W IN HEAD INJURY, INCREASED ICP, STROKE, OR NEUROSURGERY. The free water shifts into brain cells and worsens cerebral edema. This is the most tested fact about D5W.
Do not use it as a resuscitation fluid in hypovolemia or shock. Only about a tenth of it stays in the vascular space, so it will not restore blood pressure. Use an isotonic crystalloid.
NEVER give D5W with blood products - it causes red cell hemolysis. Only 0.9% normal saline may run with blood.
The 170 calories per liter are not nutrition. They protect against ketosis and spare a little protein, but a patient on D5W alone is being starved.
Monitor for hyponatremia and water intoxication with prolonged or rapid infusion: headache, nausea, confusion, lethargy, and seizures. Also monitor blood glucose in diabetic patients, because the dextrose load raises glucose.
Do not use it in a patient who is already at risk for fluid overload, and do not use plain D5W in a hypoglycemic emergency - the concentration is far too low. Use D50W.

D5W: isotonic in the bag, hypotonic in the vein, and poison for a swollen brain.

Dextrose in water 50%🚨 DANGER

Dextrose 50% in water (D50W) is a HYPERTONIC concentrated sugar solution given IV PUSH as the emergency treatment for SEVERE HYPOGLYCEMIA in a patient who is unconscious, NPO, seizing, or otherwise unable to swallow. One 50 mL prefilled syringe contains 25 grams of dextrose.

Give it through a LARGE-BORE IV in a LARGE VEIN, preferably a central line, and push SLOWLY. It is extremely hypertonic (about 2,525 mOsm/L) and is a VESICANT: extravasation causes tissue necrosis and sloughing.
Verify IV PATENCY and blood return before pushing. Assess the site during and after. If extravasation occurs, stop, aspirate, elevate, and follow the institutional extravasation protocol.
In an unconscious patient with no IV access, give GLUCAGON 1 mg IM or subcutaneously instead. Never put anything in the mouth of a patient who cannot protect their airway.
GIVE THIAMINE FIRST OR CONCURRENTLY in a patient with alcohol use disorder or malnutrition. A glucose load without thiamine can precipitate WERNICKE ENCEPHALOPATHY.
Recheck the blood glucose in 15 to 20 minutes and repeat if still low. Once the patient is awake and able to swallow, give a complex carbohydrate plus protein snack, because the effect of D50 is short-lived and rebound hypoglycemia is common - especially with a long-acting insulin or sulfonylurea on board.
Monitor for rebound HYPERglycemia and for hypokalemia (glucose drives potassium into cells). Continue to monitor closely for 24 hours per the textbook, and notify the provider and the oncoming nurse. D50 is also used in hyperkalemia treatment (with insulin, to drive potassium into cells) and in some pediatric protocols at lower concentrations (D10 or D25) because D50 is too concentrated for small veins.

D50 is the syringe for the unconscious diabetic. Big vein, slow push, thiamine first in an alcoholic, and feed them when they wake up.

Sodium chloride 0.9%⭐ HIGH YIELD

Sodium chloride 0.9% (normal saline, NS) is an ISOTONIC crystalloid that stays in the vascular space and expands blood volume. It is used for hypovolemia, dehydration, hemorrhage, shock, hyponatremia, DKA resuscitation, and it is the ONLY solution compatible with BLOOD PRODUCTS.

THE BLOOD RULE: only 0.9% NaCl may be hung with blood. Lactated Ringer's contains calcium and clots the line; dextrose solutions cause hemolysis.
It is also the standard flush for IV lines and the standard diluent for many IV medications, and it is used for irrigation and for nasal and wound care.
It contains 154 mEq/L each of sodium and chloride, which is MORE chloride than plasma. Large volumes cause HYPERCHLOREMIC METABOLIC ACIDOSIS and can worsen kidney injury, which is why balanced solutions like lactated Ringer's and Plasma-Lyte are often preferred for large-volume resuscitation.
FLUID OVERLOAD is the main risk. Use cautiously and monitor closely in heart failure, renal failure, cirrhosis, and older adults: assess lung sounds for crackles, jugular venous distention, peripheral edema, dyspnea, and daily weights. Report a weight gain over 2 to 3 pounds in a day.
It can also cause HYPERNATREMIA with excessive use. Monitor serum sodium, chloride, and bicarbonate along with intake and output.
0.9% is the reference point for tonicity: below 0.9% is hypotonic, 0.9% is isotonic, above 0.9% is hypertonic.

Normal saline is the default and the ONLY fluid that runs with blood. Watch the lungs for overload.

Sodium chloride 3%🚨 DANGER

Sodium chloride 3% is HYPERTONIC saline. It pulls water OUT of cells and into the vascular space. It is used for SEVERE SYMPTOMATIC HYPONATREMIA (seizures, coma, altered mental status) and for CEREBRAL EDEMA with increased intracranial pressure.

THE CORRECTION RATE IS THE WHOLE SAFETY ISSUE: raise the serum sodium NO FASTER than about 8 to 10 mEq/L in 24 hours (some sources say 6 to 8 in high-risk patients). Correcting too quickly causes OSMOTIC DEMYELINATION SYNDROME (central pontine myelinolysis), which produces permanent quadriparesis, dysarthria, dysphagia, and locked-in syndrome.
Administer on an INFUSION PUMP, slowly, ideally through a CENTRAL LINE, in an ICU or monitored setting. Peripheral administration causes phlebitis, pain, and infiltration; assess the site frequently.
Check SERUM SODIUM FREQUENTLY, often every 2 to 4 hours during active correction, along with neurologic status.
Monitor for FLUID OVERLOAD as water is pulled into the vasculature: crackles, dyspnea, jugular venous distention, bounding pulse, hypertension, and headache. Contraindicated or used with extreme caution in heart failure and renal failure.
Watch for cellular dehydration on the other side: thirst, dry mucous membranes, restlessness, and rising sodium above the target.
The signs the patient needs it are neurologic: hyponatremic seizures, obtundation, and coma. Asymptomatic chronic hyponatremia is corrected slowly with fluid restriction, not with 3% saline.

3% saline pulls water off the brain, but raise sodium too fast and you destroy the pons. 8 to 10 mEq in 24 hours, no more.

Ammonium chloride🚨 DANGER

Ammonium chloride is an ACIDIFYING agent. Given IV or orally, it supplies hydrogen and chloride ions to treat severe METABOLIC ALKALOSIS and HYPOCHLOREMIA that have not responded to sodium chloride and potassium chloride replacement. It is also used to acidify urine.

CONTRAINDICATED IN HEPATIC IMPAIRMENT AND RENAL FAILURE. The liver converts ammonium to urea; if it cannot, AMMONIA ACCUMULATES and causes hepatic encephalopathy, and the failing kidney cannot excrete the acid load. Monitor for confusion, asterixis, and altered mental status.
AMMONIA TOXICITY presents as pallor, sweating, irregular breathing, bradycardia, twitching, seizures, and coma. Stop the infusion and notify the provider immediately.
Give IV doses SLOWLY and DILUTED. Rapid infusion causes pain, irritation at the site, and toxicity. It is an IRRITANT - monitor the site.
Monitor: serum electrolytes, chloride, bicarbonate, pH and arterial blood gases, ammonia level, and liver and kidney function. Correcting alkalosis too fast can flip the patient into acidosis.
Because it acidifies urine, it can be used adjunctively in some poisonings and to enhance excretion of certain drugs, and it will alter the excretion of other drugs (it speeds elimination of weak bases like amphetamines and slows elimination of weak acids).
GI side effects with oral use are common: nausea, vomiting, and gastric irritation. Give with food. Think of it as the mirror image of sodium bicarbonate: bicarb treats acidosis, ammonium chloride treats alkalosis.

Ammonium chloride ACIDIFIES. The liver has to handle the ammonia, so never give it in liver failure.

Dimercaprol🚨 DANGER

Dimercaprol (BAL in Oil, British Anti-Lewisite) is a CHELATING agent for heavy metal poisoning: ARSENIC, GOLD, and MERCURY, and LEAD when combined with edetate calcium disodium. It binds the metal into a stable complex that the kidneys excrete.

IT IS PREPARED IN PEANUT OIL, so it is CONTRAINDICATED IN PEANUT ALLERGY. Always ask. This is the classic exam point.
GIVE BY DEEP INTRAMUSCULAR INJECTION ONLY - never IV. The injections are notoriously PAINFUL; rotate sites and consider local comfort measures. Use the Z-track technique.
In severe LEAD ENCEPHALOPATHY, dimercaprol is given FIRST, about 4 hours before edetate calcium disodium, because giving EDTA first can mobilize lead into the brain and worsen encephalopathy.
ALKALINIZE THE URINE to protect the kidneys: the dimercaprol-metal complex breaks down in acidic urine and releases free metal into the tubules. Maintain hydration and monitor renal function.
Expected adverse effects, usually dose-related and transient: HYPERTENSION AND TACHYCARDIA (peak 15 to 30 minutes after the dose), burning of the lips, mouth, and throat, a feeling of constriction in the chest, lacrimation, salivation, rhinorrhea, nausea and vomiting, headache, and paresthesias. Fever occurs in about 30% of children.
Contraindicated in hepatic impairment (except postarsenical jaundice) and used with caution in G6PD deficiency (hemolysis) and in renal impairment. Do NOT use it for IRON, CADMIUM, or SELENIUM poisoning - the resulting complexes are more toxic than the metal itself. Do not give iron supplements during therapy - the dimercaprol-iron complex is toxic. Wait 24 hours after the last dose.

BAL is in PEANUT oil, deep IM, and it goes in FIRST for lead encephalopathy. Never for iron.

Edetate calcium disodium🚨 DANGER

Edetate calcium disodium (calcium EDTA, Calcium Disodium Versenate) is the CHELATING agent for LEAD POISONING. It exchanges its calcium for lead and the lead-EDTA complex is excreted in the urine. Given IV or deep IM.

DO NOT CONFUSE IT WITH EDETATE DISODIUM (Na2EDTA). Edetate disodium has no calcium, binds the patient's OWN serum calcium, and causes FATAL HYPOCALCEMIA, tetany, arrhythmias, and cardiac arrest. Deaths have occurred from this exact mix-up. Read the label twice.
NEPHROTOXICITY is the dose-limiting toxicity: acute tubular necrosis. Ensure adequate HYDRATION and URINE FLOW before and during therapy, monitor urine output hourly, and monitor BUN, creatinine, and urinalysis daily. Do not give if the patient is anuric.
In LEAD ENCEPHALOPATHY, give DIMERCAPROL FIRST, about 4 hours before the EDTA, because EDTA alone can redistribute lead into the brain and worsen the encephalopathy. Avoid rapid IV infusion in encephalopathy because it raises intracranial pressure; the IM route is preferred there.
IM injections are painful; procaine is often added to the solution. Rotate sites.
Monitor serum lead levels, calcium, zinc, iron, and other trace metals - EDTA chelates them too. Rebound of the blood lead level occurs after therapy stops as lead moves out of bone, so repeat courses are often needed. Other adverse effects: fever, chills, malaise, myalgia, headache, GI upset, hypotension, and transient elevation of transaminases.
THE REAL TREATMENT IS REMOVING THE SOURCE. Chelation does not undo neurologic damage. Identify and eliminate the lead exposure (old paint, contaminated water, occupational or hobby exposure), report to public health, and screen other children in the home. Succimer (DMSA) is the oral chelator used for less severe lead poisoning.

Calcium EDTA has the calcium it needs. Plain disodium EDTA steals the patient's and stops the heart.

💉 The drugs 11

💉 Furosemide

Loop diuretic, Sulfonamide derivative

What it is for

Pulmonary edema; edema with HF, hepatic disease, nephrotic syndrome, ascites, hypertension

How it works

Inhibits reabsorption of sodium and chloride at proximal and distal tubule and in the loop of Henle

Watch for

CNS Headache, fatigue, weakness, vertigo, paresthesias
CV Orthostatic hypotension, chest pain, ECG changes, circulatory collapse
EENT Loss of hearing, ear pain, tinnitus, blurred vision
ELECT Hypokalemia, hypochloremic alkalosis, hypomagnesemia, hyperuricemia, hypocalcemia, hyponatremia …

Teaching

To discuss the need for a highpotassium diet or potassium replacement with prescriber
To rise slowly from lying or sitting position because orthostatic hypotension may occur; teach fall prevention strategies
To recognize adverse reactions that may occur: muscle cramps, weakness, nausea, dizziness; teach diabetic patients to monitor blood glucose carefully; blood glucose level …
About the entire treatment regimen, including exercise, diet, stress relief for hypertension

Antidote / reversal: 1

🔗 Full card in the drug guide

💉 Hydrochlorothiazide

Thiazide diuretic, antihypertensive, Sulfonamide derivative

What it is for

Edema, hypertension, diuresis, HF; idiopathic lower extremity edema therapy Unlabeled: Diabetes insipidus, hypercalciuria, nephrolithiasis, premenstrual syndrome, renal calculus

How it works

Acts on distal tubule and ascending limb of loop of Henle by increasing excretion of water, sodium, chloride, potassium

Watch for

CNS Drowsiness, paresthesia, depression, headache, dizziness, fatigue, weakness, fever
CV Irregular pulse, orthostatic hypotension, palpitations, volume depletion, allergic myocarditis
EENT Blurred vision
ELECT Hypokalemia, hypercalcemia, hyponatremia, hypochloremia, hypomagnesemia
GI Nausea …

Teaching

To rise slowly from lying or sitting position to prevent postural hypotension
To notify prescriber of muscle weakness, cramps, nausea, dizziness; hypokalemia is common; rash
That product may be taken with food or milk
To use sunscreen for photosensitivity

Antidote / reversal: 1

🔗 Full card in the drug guide

💉 MannitolBLACK BOX

Diuretic, osmotic; GU irrigant, Hexahydric alcohol

What it is for

Edema; promotion of systemic diuresis in cerebral edema; decrease in intraocular/intracranial pressure; improved renal function in acute renal failure, chemical poisoning, urinary bladder irrigation, kidney transplant

How it works

Acts by increasing osmolarity of glomerular filtrate, which inhibits reabsorption of water and electrolytes and increases urinary output

Watch for

CNS Dizziness, headache, confusion
CV Edema, thrombophlebitis, hypo/hypertension, tachycardia, angina-like chest pains, fever, chills, HF, circulatory overload
ELECT Fluid, electrolyte imbalances, electrolyte loss, dehydration, hypo/hyperkalemia
GI Nausea, vomiting …

Teaching

To rise slowly from lying or sitting position
About the reason for, method of treatment
To report signs of electrolyte imbalance, confusion, pain at injection site, hearing loss, blurred vision

Antidote / reversal: 1

🔗 Full card in the drug guide

💉 Spironolactone/eplerenoneBLACK BOX

Potassium-sparing diuretic, Aldosterone antagonist

What it is for

Edema of HF, hypertension, diuretic-induced hypokalemia, primary hyperaldosteronism (diagnosis, shortterm treatment, long-term treatment), edema of nephrotic syndrome, cirrhosis of liver with ascites

How it works

Competes with aldosterone at receptor sites in distal tubule, thereby resulting in the excretion of sodium chloride and water and the retention of potassium and phosphate

Watch for

CNS Headache, confusion, drowsiness, lethargy, ataxia
ELECT Hyperchloremic metabolic acidosis, hyperkalemia, hyponatremia
ENDO Impotence, gynecomastia, irregular menses, amenorrhea, postmenopausal bleeding, hirsutism, deepening voice, breast pain
GI Diarrhea, cramps, bleeding, gastritis …

Teaching

To avoid foods with high potassium content: oranges, bananas, salt substitutes, dried apricots, dates; to avoid potassium salt substitutes
That drowsiness, ataxia, mental confusion may occur; to observe caution when driving
To notify prescriber of cramps, diarrhea, lethargy, thirst, headache, skin rash, menstrual abnormalities, deepening voice, breast enlargement
To take in am to prevent sleeplessness

Antidote / reversal: 1

🔗 Full card in the drug guide

💉 Potassium chlorideHIGH ALERT

Electrolyte, mineral replacement, Potassium

What it is for

Prevention and treatment of hypokalemia

How it works

Needed for the adequate transmission of nerve impulses and cardiac contraction, renal function, intracellular ion maintenance

Watch for

CNS Confusion
CV Bradycardia, cardiac depression, dysrhythmias, arrest; peaking T waves, lowered R, depressed RST, prolonged P-R interval, widened QRS complex
GI Nausea, vomiting, cramps, pain, diarrhea, ulceration of small bowel
GU Oliguria
INTEG Cold extremities, rash

Teaching

To add potassium-rich foods to diet: bananas, orange juice, avocados, whole grains, broccoli, carrots, prunes, cocoa after product is discontinued
To avoid OTC products: antacids, salt substitutes, analgesics, vitamin preparations unless specifically directed by prescriber; to avoid licorice in large amounts because …
To report hyperkalemia symptoms (lethargy, confusion, diarrhea, nausea, vomiting, fainting, decreased output) or continued hypokalemia symptoms (fatigue, weakness, polyur …
To dissolve powder or tablet completely in ≥120 mL water or juice

🔗 Full card in the drug guide

💉 Acetylcysteine

Mucolytic; antidote—acetaminophen, Amino acid l-cysteine

What it is for

Acetaminophen toxicity; bronchitis; cystic fibrosis; COPD; atelectasis

How it works

Decreases viscosity of secretions by breaking disulfide links of mucoproteins; serves as a substrate in place of glutathione, which is necessary to inactivate toxic metabolites with acetaminophen overdose

Watch for

CNS Dizziness, drowsiness, fever, chills
CV Edema, flushing tachycardia
EENT Rhinorrhea, pharyngitis
GI Nausea, stomatitis, vomiting, anorexia
INTEG Urticaria, rash, clamminess, pruritus
RESP Bronchospasm, chest tightness, cough, dyspnea
MISC Anaphylaxis, angiedema, unpleasant odor

Teaching

That foul odor and smell may be unpleasant
To clear airway for inhalation
To report vomiting because dose may need to be repeated
Provide adequate hydration

🔗 Full card in the drug guide

💉 FlumazenilBLACK BOX

Antidote: benzodiazepine receptor antagonist, Imidazobenzodiazepine derivative

What it is for

Reversal of sedative effects of benzodiazepines

How it works

Antagonizes actions of benzodiazepines on CNS, competitively inhibits activity at benzodiazepine recognition site on GABA/benzodiazepine receptor complex

Watch for

CNS Dizziness, agitation, emotional lability, confusion, seizures, somnolence, panic attacks
CV Hypertension, palpitations, cutaneous vasodilation, dysrhythmias, bradycardia, tachycardia, chest pain
EENT Abnormal vision, blurred vision, tinnitus
GI Nausea, vomiting, hiccups
SYST Headache …

Teaching

Not to use with alcohol or other medications for at least 24 hr
That sedation may occur after treatment
To avoid hazardous activities, driving until effects are known
That amnesia may continue

🔗 Full card in the drug guide

💉 Glucagon

Antihypoglycemic

What it is for

Hypoglycemia, used to temporarily inhibit movement of GI tract as a diagnostic test

🔗 Full card in the drug guide

💉 InsulinHIGH ALERT

Antidiabetic, Intermediate-acting human insulin

What it is for

Type 1 and type 2 diabetes, usually twice daily, often paired with a short-acting insulin at meals.

How it works

Regular insulin bound to protamine so it dissolves slowly out of the injection site. Same action as any insulin once absorbed — it just arrives over hours instead of minutes, which is what gives basal-ish coverage.

Watch for

ENDO Hypoglycemia (classically in the afternoon or overnight, at the peak), weight gain.
INTEG Lipodystrophy, injection site reaction.

Teaching

The cloudy one. Roll it gently between the palms to mix — do not shake, shaking makes foam and breaks up the suspension.
Subcutaneous only. NPH must never go IV.
Onset roughly one to two hours, peak around four to twelve. Plan a snack near the peak, and know that an overnight dose puts the peak in the middle of the night.
When mixing with regular: air into NPH first, then air into regular, then draw regular up first. Clear before cloudy.

Antidote / reversal: 1

🔗 Full card in the drug guide

💉 Naloxone

Opioid antagonist, antidote, Thebaine derivative

What it is for

Respiratory depression induced by opioids, opiate agonist overdose Unlabeled: Pruritus (opiate induced)

How it works

Competes with opioids at opiate receptor sites

Watch for

CV Rapid pulse, ventricular tachycardia, fibrillation, hypo/hypertension
GI Nausea, vomiting
CNS Headache, seizures
MS Pain
INTEG Injection site reactions
MISC Withdrawal symptoms in those dependent
EENT Nasal dryness

Teaching

When patient is lucid, about the reasons for, expected results of product; for nasal administration, teach family, caregivers correct use, use of autoinjector
Opioid emergency:
Teach patient and family increased sleepiness, coma, trouble breathing are a sign of overdose; discuss family’s use of this product for overdose

🔗 Full card in the drug guide

💉 Sodium bicarbonate

Alkalinizer, NaHCO3

What it is for

Acidosis (metabolic), cardiac arrest, alkalinization (systemic/urinary), antacid, salicylate poisoning Amyotrophic lateral sclerosis (ALS)

How it works

Orally neutralizes gastric acid, which forms water, NaCl, CO2; increases plasma bicarbonate, which buffers H+ ion concentration; reverses acidosis IV

Watch for

CNS Irritability, headache, confusion, stimulation, tremors, twitching, hyperreflexia, tetany, weakness, seizures of alkalosis
CV Irregular pulse, cardiac arrest, water retention, edema, weight gain
GI Flatulence, belching, distention
META Metabolic alkalosis
MS Muscular twitching, tetany …

Teaching

Not to take antacid with milk because milk-alkali syndrome may result; not to use antacid for >2 wk
To notify prescriber if indigestion accompanied by chest pain; trouble breathing; diarrhea; dark, tarry stools; vomit that looks like coffee grounds; swelling of feet/ank …
About sodium-restricted diet; to avoid use of baking soda for indigestion
sodium phenylbutyrate/taurursodiol (Rx)

🔗 Full card in the drug guide

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Where this came from. The drug cards come from your own drug guide, fact-checked against FDA labeling. The explanations were written from your course textbook, Pharmacology (WTCS, 2e). If anything here contradicts your instructor, believe your instructor — they write the exam.

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