Pharmacology Key Concepts final

Key Concepts

• Bioavailability refers to the amount of a drug that reaches the bloodstream after administration.
  • IV administration has 100% bioavailability.
  • Oral administration has less than 100% bioavailability.
• Pharmacokinetics involves the four phases of drug movement within the body: absorption, distribution, metabolism, and excretion (ADME).
  • ADME is the order of the four phases.
• In elderly patients, excretion rates decrease, leading to a higher risk of adverse effects due to drug accumulation; starting doses should be low and increased slowly.
• The ideal therapeutic index for a drug is wide.

Routes of Administration

• Enteral routes include oral, sublingual, buccal, NG tube, and rectal.
  • They are associated with the first-pass effect, gastric irritation, slow effect, and decreased bioavailability.
• Parenteral routes include IV, IM, SubQ, ID, and epidural.
  • They have 100% bioavailability and no first-pass effect.
• Topical routes include transdermal, eye, ear, and vaginal.
• Inhalation routes include vaporization, gas inhalation, and nebulization.

Herbal Supplements

• Black cohosh is indicated for post-menopausal symptoms.
• Echinacea is used to increase immunity and prevent infection.
• Ginger is indicated for nausea, motion sickness, and morning sickness.
• Saw palmetto is indicated for benign prostatic hyperplasia (BPH).
• St. John’s wort is used for depression.

Antibiotics, Antifungals, and Antivirals

• Acyclovir is indicated for herpes simplex virus (HSV), varicella, and herpes zoster.
• Cephalexin should be avoided in patients with severe penicillin allergies.
• Efavirenz's mechanism of action (MOA) is as a non-nucleoside reverse transcriptase inhibitor (NNRTI).
• Enfuvirtide's MOA is as an entry inhibitor.
• Lopinavir's MOA is as a protease inhibitor.
• Metronidazole functions as an anti-protozoal and antibiotic, indicated for protozoal infections such as vaginal trichomoniasis, Clostridium difficile, and Helicobacter pylori.
• Nystatin is indicated for oral thrush/candidiasis.
• Patients taking tetracycline should avoid sunlight due to photosensitivity and be monitored for skin rashes.
• Vancomycin, an IV antibiotic, can cause red man syndrome and is ototoxic (ringing in ears); peak and trough levels, BUN/SCr, hearing acuity, and infusion reactions should be monitored.

Immunomodulators and Antineoplastic Agents

• Azathioprine is used for the management of Crohn's disease, rheumatoid arthritis (RA), lupus, ulcerative colitis, and other autoimmune diseases.
• Bone marrow suppression can cause fever, fatigue, bleeding/bruising, and petechiae; medications like carbamazepine and cyclosporine are potential causes.
• Cyclophosphamide can cause hemorrhagic cystitis, and patients should be monitored for blood in the urine.
• Cyclosporine can cause myelosuppression, organ rejection, hypertension (HTN), and lymphoma.
• Doxorubicin can cause heart failure; EKG monitoring is necessary.
• Interferon beta is an immunostimulant used to treat hepatitis B.
• Live vaccines, such as rotavirus, MMR, and varicella, should be avoided in immunocompromised patients (pregnant, chemo, etc.).
• Rhogam is given to pregnant patients at 28 weeks to prevent maternal antibodies from forming an immune response to the fetus.
• Tamoxifen can cause deep vein thrombosis (DVT); patients should be monitored for pain/redness/swelling in the calf area with unilateral leg swelling.
• Vincristine can cause peripheral neuropathy.

Pain, Inflammation, Substance Abuse, and Neurodegenerative Disorders

• Alcohol withdrawal can be treated with clonidine (also for decreasing blood pressure) and diazepam/lorazepam for seizures.
• Baclofen is used to manage cerebral palsy and should be tapered slowly to avoid seizures if stopped abruptly.
• Bupropion is used for smoking cessation and depression management but is contraindicated in patients with a history of seizures.
• Diazepam is a benzodiazepine used for anxiety and to manage/prevent seizures associated with alcohol withdrawal.
• Ibuprofen can cause heartburn due to peptic ulcer disease (PUD).
• Levodopa/carbidopa is used for Parkinson's disease but can cause confusion, psychosis, and hallucinations.
• Opioids can cause myosis, sedation, respiratory depression, pruritus, hypotension, constipation, urinary retention, nausea, emesis/euphoria (MORPHINE mnemonic).
• Smoking cessation can be treated with bupropion and varenicline to help with cravings, and clonidine to manage hypertension symptoms associated with withdrawal.
• Sumatriptan, a vasoconstrictor, is used for migraines but is contraindicated in patients with a history of myocardial infarction (MI); angina should be reported immediately.

Mental Health Drugs

• Carbamazepine, an anti-epileptic and mood stabilizer, can cause myelosuppression; patients should report any fevers immediately.
• Chlorpromazine, a first-generation antipsychotic, can cause extrapyramidal symptoms like restlessness and stooped posture.
• Clozapine requires monitoring of complete blood count (CBC) and neutrophil levels.
• Extrapyramidal symptoms include dystonia, parkinsonism, akathisia, restlessness, and tardive dyskinesia (DPART).
  • DPART = Dystonia, Parkinsonism's, Akathisia, Restlessness, Tardive dyskinesia
  • Dystonia: involuntary muscle contractions
  • Parkinsonism's: stooped posture
  • Akathisia: Pacing, rocking
  • Tardive dyskinesia: lip/tongue smacking, chewing motion
• Lithium requires monitoring of TSH, Na, BUN/SCr.
• Methylphenidate can cause weight loss, insomnia, and tachycardia; weight, sleep, and heart rate should be monitored.
• Phenelzine, a monoamine oxidase inhibitor (MAOI), is contraindicated with aged meats and cheeses, stimulants (due to hypertensive crisis risk), and other antidepressants (due to serotonin syndrome risk).
• Phenytoin, an anti-epileptic, can cause nystagmus (rapid eye movement).

Bone and Skin Disorders

• Alendronate, for osteoporosis, requires monitoring for jaw changes (bone density); it should be taken with a full glass of water, and the patient should remain upright for 30 minutes due to risk of esophageal issues.
• Colchicine is used for acute gout treatment, secondary to NSAIDs.
• Acute gout is treated with colchicine, while prophylaxis involves allopurinol.
• Hydroxychloroquine is used for rheumatoid arthritis and lupus; eyesight should be monitored with eye doctor visits every 6 months.
• Isotretinoin requires monitoring of liver function tests (LFTs), total cholesterol, and mood for suicidal ideations; females need a negative pregnancy test before administration and monthly.
• Mupirocin is used for impetigo.

Adrenergic and Cholinergic Drugs

• Alpha-1 adrenergic receptors cause vasoconstriction.
• Alpha-2 adrenergic receptors inhibit norepinephrine (NE) release.
• Beta-1 adrenergic receptors increase heart rate.
• Beta-2 adrenergic receptors cause bronchodilation in the lungs.
• Atropine is indicated for excessive oral secretion, organophosphate poisoning, severe bradycardia, and as a reversal agent for cholinergic crisis; adverse effects are DUCCT (dry mouth, urinary retention, constipation, confusion, tachycardia).
• Bethanechol is used for urinary retention but can cause wheezing.
• Epinephrine can cause pupil dilation, tachycardia, hyperglycemia, and decreased bladder contractions.
• Malignant hyperthermia is a risk with succinylcholine.
• Norepinephrine causes vasoconstriction and increases blood pressure.
• Oxybutynin is used for urge incontinence.
• Succinylcholine is used for short surgical procedures and muscle paralysis but can cause malignant hyperthermia (symptoms include fevers, increased HR, and sweating).
• Sympathetic stimulation causes pupil dilation, increased heart rate, bronchiole dilation, increased glycogen to glucose conversion, sweating, decreased digestive activities, vaginal contractions, and bladder relaxation.

Endocrine Drugs

• Glipizide stimulates the pancreas to release insulin and can cause hypoglycemia.
• Lispro and Aspart insulin have a 15-30 minute onset, 30-2.5 hour peak, and 3-6 hour duration; administer before meals (ac).
• Regular insulin has a 30-60 minute onset, 1-5 hour peak, and 6-10 hour duration; administer before meals (ac).
• Intermediate NPH insulin has a 1-2 hour onset, 6-14 hour peak, and 16-24 hour duration; administer once or twice daily (QD/BID).
• Glargine/Detemir insulin has a 70 minute onset, no peak, and 18-24 hour duration; administer once daily (QD).
• Levothyroxine is for hypothyroidism but can cause osteoporosis, hyperthyroidism, and cardiovascular disease; if the dose is too high, palpitations, tremors, and tachycardia may occur, and a feeling of being hot.
• Metformin, for type 2 diabetes, can cause GI upset and diarrhea.
• Prednisone, a steroid, can cause hyperglycemia and, with long-term use, increased risk of osteoporosis and infections including fungal infections.
• Propylthiouracil, an antithyroid drug, can cause agranulocytosis; TSH and WBC should be monitored for signs of infection.
  • Used in adjunct with methimazole to tx hyperthyroidism

Blood Thinners, Hematopoietic Agents, and Blood Products

• Alteplase is a fibrinolytic used to break up clots in MI, stroke, and blocked catheters.
• Oprelvekin is used to increase platelets.
• Erythropoietin is used to increase RBC production.
• Clopidogrel is an antiplatelet used to prevent future MI.
• Filgrastim is used to increase neutrophils in patients with low WBC.
• Heparin requires monitoring of aPTT; protamine is the antidote, and CBC should be used to monitor for thrombocytopenia.
• Warfarin requires monitoring of INR; vitamin K or fresh frozen plasma is the antidote.

Cardiovascular Drugs

• Atorvastatin is used to lower LDL but can cause muscle pain, hepatitis, and elevated LFTs.
• Cholestyramine lowers cholesterol but decreases absorption of vitamins KADE and causes GI upset.
  • Educate pt to increase KADE intake, don't take w/ other meds d/t preventing absorption
• Digoxin can cause vomiting and visual halos; hold if HR < 60; Digoxin toxicity includes anorexia, palpitations, fatal arrhythmias, N/V, halos.
• Diltiazem (similar to verapamil) is a non-DHP calcium channel blocker that decreases HR; hold if HR < 60.
• Metoprolol is a beta blocker that decreases HR.
• Nitroglycerin is used for angina and can cause dizziness and hypotension.
• Ramipril is an ACE inhibitor used for lowering BP but can cause a dry cough, angioedema, and hyperkalemia.

Diuretics, IV Fluids, and Antidotes

• Furosemide, a loop diuretic, can cause hypokalemia and ototoxicity (tinnitus).
• Hydrochlorothiazide, a thiazide diuretic, decreases potassium and is contraindicated in patients with sulfa allergies.
• Mannitol is an osmotic diuretic used for increased intracranial pressure (ICP) / intraocular pressure (IOP); electrolytes, and K levels should be monitored.
• Potassium chloride is used to increase potassium levels; do not administer IV push and monitor EKG if IV drip.
• Sodium bicarbonate is used to lower high potassium levels.
• Spironolactone is used to increase potassium levels; it can cause hyperkalemia.

Respiratory Drugs

• Acetylcysteine is used for acetaminophen overdose, cystic fibrosis as a mucolytic, and pre-contrast renal protection.
• Albuterol is a rescue inhaler for acute asthma exacerbation.
• First-generation antihistamines (diphenhydramine) cause sedation.
• Second-generation antihistamines (fexofenadine) cause little to no sedation.
• Acute asthma exacerbation is treated with albuterol.
• Beclomethasone inhaler is an inhaled steroid for asthma; patients should rinse their mouth out after use to prevent thrush.
• Diphenhydramine (1st gen antihistamine) causes sedation.
• Fexofenadine (2nd gen antihistamine) causes little to no sedation and should be started 3-4 days before allergy season.
• Phenylephrine is used for nasal congestion for only 3-5 days to avoid rebound nasal congestion.

Eye and Ear Disorders

• Ciprofloxacin/dexamethasone ear drops are used for otitis externa.
• During eye drop administration, hands should be washed before and after; the eye dropper should not touch the eye, and pressure should be applied on the nasal side of the eye.
• Latanoprost increases the outflow of aqueous humor (AH) and is used for open-angle glaucoma.
• Otitis externa is treated with ciprofloxacin/dexamethasone.

Gastrointestinal Medications

• Metoclopramide is used for gastric reflux and vertigo but is contraindicated in Parkinson's disease and can cause Parkinson's-like side effects.
• Omeprazole is a proton pump inhibitor that decreases the amount of acid pumped into the stomach.
• Ondansetron is used for chemotherapy-induced nausea/vomiting and can cause prolonged QT intervals, which require EKG monitoring.
• Orlistat, a weight loss drug, can cause oily stool.
• Peptic ulcer disease triple therapy includes omeprazole, amoxicillin, and clarithromycin.
• Sucralfate forms a sugary coating to line the stomach and should be taken 3-4 times a day.

Reproductive Drugs

• Betamethasone injection is used in premature labor to mature the fetal lungs.
• Clomiphene is used for infertility but can cause multiple births (twins/triplets).
• Estrogens are used for menopausal symptoms, acne, and to prevent osteoporosis but are contraindicated in patients with a history of breast cancer.
• Finasteride is used for BPH.
• Magnesium sulfate is used for preterm labor, eclampsia (HTN), asthma, and dysrhythmias; if the dose is too high, it can cause muscle weakness.
• Misoprostol is used to induce labor and to prevent gastric ulcers caused by GERD but is contraindicated in pregnancy if used for GERD.
• Oxytocin is used to induce labor and enhance labor contractions.
• Progesterone is used for menopausal symptoms and endometriosis but can cause breakthrough bleeding.
• Sildenafil is used for erectile dysfunction (ED) and pulmonary hypertension but is contraindicated with nitroglycerin use (due to fatal hypotension); it can cause hypotension and visual changes; avoid grapefruit.
• Tamsulosin, an alpha-1 blocker, causes vasodilation and is used for BPH; it can cause orthostatic hypotension (dizziness upon standing), hypotension, and dizziness.
• Terbutaline is used for asthma but can cause palpitations.
• Testosterone can cause acne and aggression.