Editing Pharmacology (section)

== Major Drug Classes by Body System ==

=== Cardiovascular ===

* '''ACE inhibitors''' (lisinopril): lower blood pressure and reduce cardiac remodeling. Adverse effects: persistent dry cough, hyperkalemia, first-dose hypotension, acute kidney injury, and rarely angioedema, which is an emergency. Contraindicated in pregnancy. If cough is intolerable, an angiotensin receptor blocker is the usual substitute.
* '''ARBs''' (losartan): similar profile without the cough. Still cause hyperkalemia and are contraindicated in pregnancy.
* '''Beta blockers''' (metoprolol, atenolol, carvedilol): decrease heart rate, contractility, and blood pressure. Hold and notify for apical pulse under 60 or systolic blood pressure under 90 unless otherwise ordered. Never stop abruptly because rebound tachycardia, hypertension, and angina can occur. Use caution in asthma with nonselective agents. Beta blockers '''mask''' the tachycardia and tremor of hypoglycemia, which is a key teaching point in diabetes.
* '''Calcium channel blockers''': dihydropyridines (amlodipine, nifedipine) act mainly on vessels and cause peripheral edema, flushing, and headache. Nondihydropyridines (verapamil, diltiazem) also slow the heart rate and are used for rate control. Verapamil commonly causes constipation. Grapefruit juice raises levels.
* '''Diuretics''': loop diuretics (furosemide, bumetanide) are potent and cause hypokalemia, hyponatremia, hypomagnesemia, hypocalcemia, dehydration, and ototoxicity when pushed rapidly. Give intravenous furosemide slowly. Thiazides (hydrochlorothiazide) cause hypokalemia, hyperglycemia, hyperuricemia, and hypercalcemia. Potassium-sparing agents (spironolactone, triamterene) cause '''hyper'''kalemia; spironolactone also causes gynecomastia. Teach patients to take diuretics in the morning to avoid nocturia and to weigh daily, reporting a gain of 2 to 3 pounds in a day or about 5 pounds in a week.
* '''Digoxin''': positive inotrope, negative chronotrope. Therapeutic serum range is roughly 0.5 to 2.0 ng/mL, with 0.5 to 0.9 ng/mL targeted in heart failure. Take the apical pulse for a full minute and hold for a rate under 60 in an adult. Early toxicity presents as anorexia, nausea, vomiting, fatigue, visual disturbance including yellow-green halos, and dysrhythmias. '''Hypokalemia potentiates digoxin toxicity''', so watch potassium closely in patients also taking loop diuretics. The antidote is digoxin immune Fab.
* '''Nitrates''' (nitroglycerin): venodilation reduces preload and relieves angina. Sublingual dosing for an outpatient is one tablet, repeated every 5 minutes up to three doses, with emergency services called per current guidance if pain is unrelieved. Expect headache. Absolutely contraindicated with phosphodiesterase-5 inhibitors such as sildenafil or tadalafil because of profound hypotension. Hold for systolic blood pressure under 90. Transdermal nitrates require a nitrate-free interval, typically 10 to 12 hours, to prevent tolerance.
* '''Statins''': lower low-density lipoprotein. Monitor for myalgia and, rarely, rhabdomyolysis; teach patients to report unexplained muscle pain, tenderness, weakness, or dark urine. Monitor liver enzymes at baseline. Avoid grapefruit juice with simvastatin, lovastatin, and atorvastatin. Contraindicated in pregnancy.
* '''Antidysrhythmics''': amiodarone is broadly effective but causes pulmonary toxicity, thyroid dysfunction (both hypo and hyper), hepatotoxicity, corneal microdeposits, blue-gray skin discoloration, and QT prolongation. Adenosine is given as a rapid intravenous push followed immediately by a saline flush and produces a brief period of asystole.
* '''Vasoactive infusions''' (registered nurse scope): norepinephrine, dopamine, epinephrine, phenylephrine, vasopressin, nitroglycerin drip, nitroprusside, and dobutamine are titrated to a hemodynamic target. Give through a central line when possible because extravasation of a vasoconstrictor causes tissue necrosis; the antidote for that extravasation is phentolamine infiltrated locally. Nitroprusside carries a risk of cyanide and thiocyanate toxicity with prolonged or high-dose use and must be protected from light.

=== Anticoagulants, Antiplatelets, and Thrombolytics ===

* '''Heparin (unfractionated)''': monitored by aPTT, with a therapeutic target commonly 1.5 to 2.5 times the control value, or by anti-Xa level per facility protocol. Antidote is '''protamine sulfate'''. Watch for heparin-induced thrombocytopenia, an immune reaction in which the platelet count falls, typically 5 to 10 days after exposure, and the patient paradoxically clots. If suspected, stop all heparin including flushes and notify the provider.
* '''Enoxaparin''': low molecular weight heparin, more predictable, usually no routine monitoring, dose-reduced in renal impairment. Same subcutaneous technique points listed above.
* '''Warfarin''': vitamin K antagonist. Monitored by prothrombin time and INR, with a usual therapeutic INR of 2.0 to 3.0 for atrial fibrillation and venous thromboembolism, and 2.5 to 3.5 for a mechanical mitral valve. Onset takes several days, so heparin bridging is common. Antidote is '''vitamin K (phytonadione)'''; fresh frozen plasma or prothrombin complex concentrate is used for urgent reversal. Teach '''consistent''', not zero, intake of vitamin K rich foods such as spinach, kale, broccoli, and Brussels sprouts. Contraindicated in pregnancy. Many interactions, including antibiotics, amiodarone, and NSAIDs.
* '''Direct oral anticoagulants''': apixaban and rivaroxaban (factor Xa inhibitors, reversal agent andexanet alfa) and dabigatran (direct thrombin inhibitor, reversal agent idarucizumab). No routine INR monitoring.
* '''Antiplatelets''': aspirin, clopidogrel, ticagrelor. Bleeding and bruising are the main risks. Clopidogrel effect is reduced by strong CYP2C19 inhibitors such as omeprazole.
* '''Thrombolytics''' (alteplase): dissolve existing clot in acute ischemic stroke, ST elevation myocardial infarction, and massive pulmonary embolism. Absolute exclusions include active internal bleeding, recent intracranial hemorrhage, and recent intracranial or intraspinal surgery. During and after infusion, minimize venipunctures and injections and monitor neurologic status closely.

Universal anticoagulant teaching: use a soft toothbrush and an electric razor, avoid contact sports, report black tarry stools, pink or brown urine, bleeding gums, nosebleeds that will not stop, unusual bruising, or a fall with head strike, and wear medical identification.

=== Endocrine ===

* '''Insulin''': the only insulin given intravenously is '''regular''' insulin. Approximate profiles: rapid acting (lispro, aspart, glulisine) onset about 15 minutes, peak about 1 hour, give with the meal in front of the patient; short acting regular onset about 30 to 60 minutes, peak about 2 to 4 hours; intermediate NPH onset about 1 to 2 hours, peak about 4 to 12 hours (the only cloudy insulin, and the only one routinely mixed); long acting glargine and detemir with no pronounced peak and no mixing with other insulins. When mixing, draw '''clear before cloudy''' (regular before NPH) after injecting air into both vials. Hypoglycemia signs: shakiness, diaphoresis, tachycardia, hunger, confusion, irritability. Treat a conscious patient with 15 grams of fast-acting carbohydrate, recheck in 15 minutes, and repeat as needed; treat an unconscious patient with intravenous dextrose or glucagon.
* '''Oral antidiabetics''': metformin does not cause hypoglycemia alone and carries a risk of lactic acidosis; hold it before and after iodinated contrast studies per protocol and check renal function. Sulfonylureas (glipizide, glyburide) '''do''' cause hypoglycemia. SGLT2 inhibitors (''-flozin'') cause genital mycotic and urinary infections and euglycemic ketoacidosis. GLP-1 agonists (''-tide'') cause nausea and delay gastric emptying.
* '''Levothyroxine''': take in the morning on an empty stomach with water, at least 30 to 60 minutes before food, and separate from calcium, iron, and antacids by about 4 hours. Signs of excess dose mimic hyperthyroidism: tachycardia, palpitations, weight loss, heat intolerance, insomnia. Lifelong therapy.
* '''Corticosteroids''' (prednisone, methylprednisolone): expect hyperglycemia, immunosuppression and masked infection, fluid retention, hypokalemia, mood changes, osteoporosis and cushingoid features with long-term use, and delayed wound healing. Take with food. '''Never stop abruptly''' after prolonged therapy because adrenal insufficiency can result; taper.

=== Neurologic and Psychiatric ===

* '''Opioids''' (morphine, hydromorphone, fentanyl, oxycodone): the most dangerous adverse effect is respiratory depression, and sedation precedes it, so monitor the level of arousal. Constipation is the effect that does not develop tolerance, so start a bowel regimen. Antidote is '''naloxone''', which has a shorter duration than most opioids, so continued monitoring and repeat dosing may be needed. Hydromorphone is substantially more potent than morphine milligram for milligram, a frequent source of serious errors.
* '''Non-opioid analgesics''': acetaminophen has a maximum of 4 grams per day for most healthy adults, with lower limits in liver disease, chronic alcohol use, and older adults; the antidote for overdose is '''acetylcysteine'''. NSAIDs cause gastrointestinal bleeding, kidney injury, and fluid retention, and should be taken with food and avoided with anticoagulants.
* '''Benzodiazepines''' (lorazepam, diazepam, midazolam): sedation, respiratory depression especially when combined with opioids, and dependence. Antidote is '''flumazenil''', used cautiously because it can precipitate seizures in chronic users.
* '''Antiepileptics''': phenytoin has a narrow therapeutic range of roughly 10 to 20 mcg/mL and causes gingival hyperplasia (teach meticulous oral care), nystagmus and ataxia with toxicity, and severe skin reactions. Intravenous phenytoin is compatible with normal saline only, not dextrose, and must be given slowly. Valproate and carbamazepine require monitoring of liver function and blood counts; carbamazepine is a strong enzyme inducer. Levetiracetam is associated with behavioral changes.
* '''Antidepressants''': SSRIs take 2 to 4 weeks for mood response, and energy may improve before mood, transiently increasing suicide risk in young patients. Watch for '''serotonin syndrome''': agitation, hyperthermia, hyperreflexia, clonus, diaphoresis, and tremor, especially when an SSRI is combined with another serotonergic drug such as tramadol, triptans, linezolid, or St. John's wort. Tricyclics cause anticholinergic effects, orthostatic hypotension, and cardiac conduction problems, and are dangerous in overdose. MAO inhibitors require a '''tyramine-restricted diet''' (avoid aged cheese, cured and smoked meats, fermented soy, tap beer, and overripe or fermented foods) to prevent hypertensive crisis, and require a washout period of about 2 weeks when switching to or from an SSRI.
* '''Lithium''': therapeutic serum range about 0.6 to 1.2 mEq/L; levels above 1.5 mEq/L are toxic. Early toxicity presents as nausea, vomiting, diarrhea, fine tremor, and thirst; advancing toxicity brings coarse tremor, confusion, ataxia, and seizures. Teach adequate and consistent sodium and fluid intake, since dehydration, sodium loss, thiazide diuretics, NSAIDs, and ACE inhibitors all raise lithium levels. Monitor thyroid and renal function.
* '''Antipsychotics''': first generation agents (haloperidol, fluphenazine) most often cause extrapyramidal symptoms including acute dystonia, akathisia, pseudoparkinsonism, and tardive dyskinesia, which may be irreversible. Second generation agents (risperidone, olanzapine, quetiapine, aripiprazole) carry a greater metabolic burden with weight gain, hyperglycemia, and dyslipidemia. '''Neuroleptic malignant syndrome''' is a medical emergency: high fever, lead-pipe rigidity, altered mental status, autonomic instability, and elevated creatine kinase. Clozapine requires ongoing absolute neutrophil count monitoring because of agranulocytosis risk.

=== Respiratory ===

* '''Short-acting beta-2 agonists''' (albuterol): rescue therapy; expect tachycardia and tremor. Increasing rescue inhaler use signals worsening control.
* '''Inhaled corticosteroids''' (fluticasone, budesonide): controller therapy, not rescue. Rinse the mouth after use.
* '''Anticholinergics''' (ipratropium, tiotropium): dry mouth; caution in narrow-angle glaucoma and urinary retention.
* '''Leukotriene modifiers''' (montelukast): controller therapy with a warning for neuropsychiatric effects.
* '''Theophylline''': narrow therapeutic range of roughly 10 to 20 mcg/mL, with toxicity presenting as tachycardia, nausea, restlessness, and seizures. Caffeine adds to the effect.

=== Gastrointestinal ===

* '''Proton pump inhibitors''': take before the first meal of the day. Long-term risks include ''Clostridioides difficile'' infection, fracture, hypomagnesemia, and vitamin B12 deficiency.
* '''Histamine-2 blockers''' and '''antacids''': antacids interfere with the absorption of many drugs, so separate doses by 1 to 2 hours. Aluminum-containing antacids cause constipation, magnesium-containing antacids cause diarrhea.
* '''Antiemetics''': ondansetron prolongs the QT interval. Promethazine is a vesicant, causing severe tissue injury with extravasation, and is preferably given by a route other than peripheral intravenous push. Metoclopramide can cause extrapyramidal symptoms and tardive dyskinesia.

=== Anti-infectives ===

* Obtain '''cultures before''' the first antibiotic dose whenever feasible, and teach patients to complete the full course.
* '''Penicillins and cephalosporins''': monitor for allergy and anaphylaxis; cross-sensitivity with cephalosporins exists but is lower than historically taught.
* '''Vancomycin''': monitor trough levels and renal function. Infuse over at least 60 minutes; rapid infusion causes an infusion reaction with flushing of the face, neck, and upper torso. Ototoxicity and nephrotoxicity are the main toxicities.
* '''Aminoglycosides''' (gentamicin, tobramycin): nephrotoxic and ototoxic. Monitor peaks, troughs, creatinine, and hearing, and report tinnitus or new hearing loss.
* '''Fluoroquinolones''': tendinitis and tendon rupture, QT prolongation, photosensitivity, and central nervous system effects. Separate from antacids, calcium, iron, and zinc by at least 2 hours.
* '''Tetracyclines and doxycycline''': avoid in pregnancy and in young children because of tooth discoloration; chelated by dairy, antacids, and iron; photosensitivity.
* '''Macrolides''': gastrointestinal upset, QT prolongation, and significant CYP interactions with erythromycin and clarithromycin.
* '''Sulfonamides''' (trimethoprim-sulfamethoxazole): encourage fluids, watch for rash including Stevens-Johnson syndrome, hyperkalemia, and interaction with warfarin.
* '''Metronidazole''': avoid alcohol during therapy and for at least 3 days after because of a disulfiram-like reaction; may cause a metallic taste and dark urine.
* '''Antitubercular therapy''': isoniazid causes peripheral neuropathy, prevented with pyridoxine (vitamin B6), and hepatotoxicity. Rifampin turns urine, sweat, and tears orange, permanently stains soft contact lenses, and reduces the effectiveness of oral contraceptives. Ethambutol causes optic neuritis with changes in visual acuity and red-green color discrimination.

=== Oncology and Immune ===

Cytotoxic chemotherapy causes bone marrow suppression with a nadir typically 7 to 14 days after administration, mucositis, alopecia, nausea, and infertility. Teach infection precautions and report a temperature of 38 degrees Celsius or 100.4 degrees Fahrenheit or higher as a potential neutropenic emergency. Many agents are vesicants requiring immediate action for extravasation. Doxorubicin is cardiotoxic with a lifetime cumulative dose limit, cisplatin is nephrotoxic and ototoxic, vincristine causes peripheral neuropathy and is '''fatal if given intrathecally''', and methotrexate is rescued with leucovorin. Preparation and administration of chemotherapy require specialized certification.