Cardiac and Antiarrhythmic Medications

• The chapter aims to provide a basic understanding of major drug classifications, their names, and how they work.
• This knowledge helps imaging technologists quickly assess a patient's medical status.

Cardiac Medications

• Encompass a broad range of agents used to treat cardiovascular pathologies.

Antiarrhythmic Medications (or Antidysrhythmic)

• Affect the myocardium's electrical conduction system.
• Actions vary among individual drugs but generally block the SA node, AV node, His-Purkinje system, or electrical membrane current in myocardial cells.
• Achieved by blocking electrolyte channels (sodium, calcium, potassium) or beta receptors in the myocardium.
• Aim to suppress excess electrical conduction and reduce arrhythmia production.
• Common examples: lidocaine, procainamide, flecainide, disopyramide, mexilitine, moricizine, amiodarone, atenolol, metoprolol, acebutolol, esmolol, labetolol, sotalol, propafenone, diltiazem, verapamil, adenosine, ibutilide, dofetilide, and digoxin.

Antihypertensive Medications

• Assist in lowering blood pressure to safe levels and improve heart failure symptoms.
• Can improve the duration of life.
• Actions vary among drugs; patients with severe hypertension often require multiple medications.
• Work by causing vasodilation, decreasing heart rate, decreasing sympathetic nerve outflow, decreasing sodium and water retention, inhibiting the renin-angiotensin-aldosterone system, or direct vasodilation.
• Examples include verapamil, diltiazem, nifedipine, nicardipine, amlodipine, nisoldipine, captopril, enalopril, fosinopril, lisinopril, trandolapril, ramipril, quinapril, moexipril, perindopril, valsartan, olmesartan, candesartan, telmisartan, propranolol, acebutolol, atenolol, metoprolol, labetolol, nadolol, penbutolol, bisoprolol, pidolol, furosemide, bumetanide, torsemide hydrochlorothiazide, chlorothiazide, amiloride, sprionolactone, eprenolone, metolazone, hydralazine, isosorbide mononitrate, isosorbide dinitrate, bosentan, prazocin, terazosin, minoxidil, clonidine, guanethidine, methyldopa, and reserpine.

Heart Failure Medications

• A variety of classes with positive inotropic effects (increased contraction force).
• Digoxin increases myocardial contraction force by stimulating calcium release from the sarcoplasmic reticulum and can block the AV node, useful in atrial fibrillation.
• Intravenous medications like dobutamine, milrinone, dopamine, norepinephrine, and epinephrine increase contraction force and blood pressure.
• Patients on these meds are less stable and can develop problems quickly.

Lipid-lowering Medications

• Used to lower serum cholesterol and improve outcomes for patients with coronary syndromes or hypercholesterolemia.
• Common drugs include lovastatin, simvastatin, pravastatin, ezetimibe, fluvastatin, atorvastatin, gemfibrozil, colestipol, cholestyramine, and niacin.

Diuretics

• Frequently called "water pills" to eliminate excess fluid and sodium from the bloodstream, decreasing vessel pressure.
• Overuse can cause dehydration and kidney failure.
• Common types include hydrochlorothiazide, chlorthalidone, furosemide, torsemide, bumetanide, acetazolamide, amiloride, chlorothiazide, ethacrynic acid, spironolactone, triamterene, metalozone, and indapamide.

Anticoagulant, Antiplatelet, and Thrombolytic Medications

• Patients on these are at risk for bleeding.
• Imaging technologists should recognize stroke symptoms.
• Anticoagulants are used for patients with a history or potential for blood clots.
• Warfarin prevents vitamin K absorption, affecting blood-clotting factors.
• Heparin, enoxaparin, deltaparin, fundoparinox, bivalirudin, lepirudin, and argatroban affect thrombin activity to inhibit clot formation.
• Antiplatelet agents are for patients who have experienced an acute ischemic event.
• Aspirin, clopidogrel, and dipyridamole are common oral medications for inhibiting platelet effects.
• Eptifibatide, abciximab, and tirofiban are intravenous medications for inhibiting platelet function.
• Thrombolytics break up new clots, such as in acute myocardial infarction or stroke.
• Alteplase, retaplase, streptokinase, tenecteplase, and urokinase are common examples.
• Patients on these are at high risk for bleeding; use caution with IV sites.

Analgesic Medications

• Prescribed more than any other medication for acute and chronic pain syndromes.
• Subclasses include narcotics, nonsteroidal antiinflammatory drugs, muscle relaxants, and acetaminophen.
• Narcotics stimulate opioid receptors, decreasing pain perception.
• They are potent analgesics with addiction potential and are carefully controlled.
• Respiratory depression leading to arrest is a risk; naloxone reverses the effects.
• Common examples include morphine, meperidine, fentanyl, hydromorphone, hydrocodone, codeine, oxycodone, alfentanyl, remifentanyl, tramadol, pentazocine, nalbuphine, and butorphanol.
• Nonsteroidal antiinflammatory drugs (NSAIDs) treat pain related to inflammation.
• Work by inhibiting mediators responsible, such as arthritis and injury by stimulating a nociception.
• Can cause platelet dysfunction, stomach ulceration, and kidney failure.
• Common NSAIDs include ibuprofen, naproxen, nabumetone, diclofenac, ketorolac, indomethacin, fenoprofen, rofecoxib, celocoxib, and valdecoxib. Aspirin is similar to NSAIDs.
• Muscle relaxants treat pain associated with muscle spasms.
• May affect breathing by decreasing the strength of respiratory muscles.
• Common examples include cyclobenzaprine, baclofen, diazepam, lorazepam, clonazepam, alprazolam, methocarbamol, and metaxalone.
• Acetaminophen is a common analgesic, acts by inhibiting prostaglandins in the central nervous system.
• Must not exceed 4000 mg per day due to liver damage risk; long-term use can damage kidneys and heart.

Antihistamine Medications

• Block histamine to reduce symptoms like itching, inflammation, and respiratory issues.
• Common antihistamines include hydroxyzine and diphenhydramine; newer forms like fexofenadine, loratadine, and cetirizine are less sedating.
• Usually sedating, can cause respiratory depression, especially with analgesics.

Endocrine Medications

• Diabetes and hypothyroidism are common.
• Antidiabetic medication is needed for sugar balance.
• Some patients are insulin-dependent (type 1); others are non-insulin-dependent (type 2).
• Types of insulin include ultrashort, short, intermediate, long, and ultralong acting.
• Patients may require regular meals on the administration of insulin.
• Non-insulin-dependent patients may take oral medications like glimeprimide, glipizide, glyburide, rosiglitazone, pioglitazone, nateglinide, and metformin.
• Metformin should be held before and for 48 hours after contrast agent use to prevent metabolic acidosis.
• Thyroid medication for hypothyroidism replaces lacking thyroid hormone.
• Common preparations include levothyroxine, thyroxine, liothyronine, and desiccated thyroid; to block thyroid function include methimazole and propylthiouracil.

Central Nervous System Medications

• Antiseizure medications prevent and treat seizure disorders.
• Some patients may require multiple medications and a failure can be fatal.
• Examples include phenytoin, fosphenytoin, ethotoin, metphenytoin, diazepam, clonazepam, lorazepam, valproic acid, divalproex, topiramate, carbamazepine, oxcarbazine, phenobarbital, amobarbital, pentobarbital, secobarbital, ethosuximide, methsuximide, felbamate, gabapentin, lamotrigine, tiagabine, zonisamide, and levetiracetam.
• Antipsychotic medications treat psychotic episodes like schizophrenia, paranoid behaviors, hallucinations, delusions, bipolar disorder, agitation, antisocial behaviors, and mania.
• Can take weeks or months to become effective.
• Common examples include haloperidol, valproic acid, divalproex, olanzapine, clozapine, quetiapine, aripiprazole, chlorpromazine, fluphenazine, triflupromazine, loxapine, mesoridazine, thioridazine, amoxepine, perphenazine, risperidone, ziprasidone, thiothixine, and pimozide.
• Antidepressants treat depression by enhancing CNS serotonin and norepinephrine levels.
• Requires weeks of therapy to become fully active.
• Common antidepressants include amitriptyline, nortriptyline, desipramine, imipramine, protriptyline, trimipramine, amoxapine, maprotiline, isocarboxazid, tranylcypromine, sertraline, citalopram, escitalopram, fluoxetine, venlafaxine, mirtazapine, trazadone, buproprion, and nefazodone.
• Antianxiety medications treat anxiety states, used with claustrophobic patients in CT and MRI scans.
• Enhancing the gamma-aminobutyric acid and serotonin in the limbic system.
• Drugs include diazepam, lorazepam, midazolam, alprazolam, chlordiazepoxide, clonazepam, and buspirone.

Antiinfective Agents

• Antibiotics and antiinfectives kill or suppress microorganisms.
• Antibiotics target bacteria, antifungals target fungi, and antivirals target viruses.
• Act at the cellular level to affect the cell wall, enzymatic activity, or DNA function.
• Antibiotics include penicillins, cephalosporins, carbapenams, tetracyclines, macrolides, lincosamides, and nitroimidazoles.
• Antifungals include amphotericin B, fluconazole, voriconazole, caspofungin, clotrimazole, flucytosine, itraconazole, miconazole, ketoconazole, nystatin, and terbinazine.
• Antivirals include acyclovir, famciclovir, ganciclovir, ribavirin, valacyclovir, valganciclovir, rimantidine, foscarnet, and interferon.

Chemotherapy Agents

• Designed to kill rapidly growing cells (cancerous) by altering cellular division.
• Require special precautions due to toxicity; avoid skin contact.
• Secreted bodily fluids can pose a threat; use universal precautions.
• Examples include adriamycin, etoposide, vincristine, VP-16, cyclophosphamide, bleomycin, flurouracil, doxirubucin, paclitaxel, docetaxel, methotrexate, and nitrogen mustard.

Herbal Products

• See corresponding chapter.