Pharmacology review commonly used drugs

Pharmacology Review

Commonly Used Drugs

Antibiototics Antibiotics are effective against bacteria and

are considered bacteriostatic or bactericidal. Their spectrum is determined based on the drugs effectiveness against different gram negative, gram positive or acid fast bacteria. Bacteriostatic- Inhibits or reproduction of bacteria. Bactericidal- Kills the bacteria.

Antibiotics Penicillins

Works by binding the penicillin binding protein causing cell wall lysis

Bactericidal Spectrum primarily gram positive bacteria, beta-

lactamase bacteria are resistant Most common antibiotic class to cause an allergic reaction Medications- Ampicillin, Amoxicillin, Penicillin G, Clavamox,

penicillin V, PiperacillinAmpicilla Carbapenems

Class of beta-lactam antibiotics wide range of antibacterial activity. Inhibits cell wall synthesis.

Bactericidal Medications- Imipenem and meropenem

Antibiotics Cephalosporins

Works by interfering with cell wall synthesis by binding to the penicillin binding protein.

Related to penicillins but also has activity against beta-lactamase. Side effects- GI upset, fever, lethargy, tachypnea, pain at injection

site, and nephrotoxicity. Penetrate soft tissue and fluid very well.

First generation mostly gram positive. Second generation gram positive and gram negative. Third generation mainly used against gram negative. Fourth generation extended spectrum and increased resistance hydrolysis

and beta-lactamase bacteria. Oral forms- Cephalexin, Cephradine, Cefadroxil, Cefaclor,

cefpodoxime Parenteral forms- Cefazolin, Cefapirin, Cephaloridine, ceftiofur,

cefoxitin, cefovecin(convenia)

Antibiotics Tetracyclines

Works by inhibiting protein synthesis by binding 30s ribosomal subunit

Broad spectrum effective against gram positive and gram negative. Bacteriostatic Has antiinflammatory and immunomodulating effects Side effects- Very commonly causes GI upset, esophageal strictures

in cats, yellowing of teeth and bones when given to juveniles, hepatotoxic and renal toxic. DO NOT GIVE IV IN HORSES.

Medications- Doxycycline, Minocycline, tetracycline, oxytetracycline. Aminoglycosides

Not readily absorbed through GI tract. Works by irreversibly binding to 30s ribosomal subunit. Broad spectrum- most effective against gram negative bacteria. Not approved for use in food-producing animals. Medications- Streptomycin, gentamycin, amikacin, neomycin,

tobramycin.

Antibiotics Fluoroquinolones

Works by inhibiting DNA gyrase which inhibits DNA synthesis. Broad spectrum effective against gram negative and gram

positive bacteria. Side effects- GI upset, cartilage deformities in growing

animals, retinal damage in cats. Medications- Enrofloxacin/Baytril, Marbofloxacin/zeniquin,

Orbifloxicin, Sulfonamides

Work by Inhibiting folic acid synthesis Bacteriostatic Side effects- MULTIPLE SIDE EFFECTS! Vomiting, diarrhea,

anorexia, KCS, bone marrow depression, fever, polyarthritis, hepatic necrosis, hemolytic anemia, and hypothyroidism.

Antibiotics Macrolides and Lincosamides

Inhibits protein synthesis by binding 50s ribosomal subunit

Bacteriostatic Broad spectrum Medications- Erythromycin, Tylosin, Clindamycin,

Azithromycin.

Antifungals Drugs used to treat fungal(Mycotic) infections Fungicidal- destroys, kills fungi. Fungistatic- Having an inhibitory effect on

growth or reproduction of fungi. Topical- ringworm, yeast Systemic- Cryptococcosis, Coccidiomycosis,

Histoplasmosis, Blastomycosis.

Antifungals Nystatin

Works by inhibiting membrane permeability. Fungicidal Effective for Candida infections in dogs, cats and

bird. Amphotericin B

Used IV ONLY! Works by disrupting membrane permeability Fungicidal Used in systemic fungal infections

Antifungals Ketoconazole

Works by impairing ergosterol synthesis affecting membrane permeabilty.

Not recommended for use in cats. Used to treat systemic fungal disease, dermatophytosis

and cushings disease. Side effects- Hepatotoxic, fever infertility in male dogs

Itraconazole Works by altering membrane permeability Fungistatic Effective in systemic fungal infection. Drug of choice of

blastomycosis Side effects- Anorexia, hepatotoxicity, vasculitis.

Antifungals Fluconazole

Triazole antifungal Fungistatic Alters cellular membrane Clinical uses- cryptococcus and other systemic fungal infections. Side effects- Hepatotoxic, vomiting, diarrhea anorexia.

Flucytosine- Used with other antifungal drugs Fungistatic Inhibits DNA synthesis Clinical uses- Systemic fungal infection cryptococcus and

candida Side Effects- GI upset, bone marrow suppression, oral ulcers,

increased liver enzymes.

Antifungals Griseofulvin

Disrupts cell division Fungistatic Increased absorption with a fatty meal Clinical uses- Dermatophytosis Side effects- hepatotoxic, vomiting and diarrhea.

Do not use in pregnant or breeding animals.

Respiratory Drugs Drugs to treat respiratory disease

administered by oral or parenteral routes Aerosolization or nebulization allows delivery

of high concentrations of drugs directly into airway.

Respiratory drugs Expectorants-Liquifies and dilutes viscous secretions to

help evacuate secretions. Used to treat a productive cough Acts directly on mucus secreting glands, reducing mucus

adhesiveness Medications- Guaifenesin, iodide preperations and hypertonic

saline Mucolytics- Decreases viscosity of secretions by altering

chemical composition of mucus May be nebulized and has few side effects Medication-Acetylcysteine(also used to treat acetaminophen

toxicity) Antitussives- Suppresses cough act centrally(Cough center

in brain) or peripherally(Cough receptors in airways). Medications- Butorphenol, Hydrocodone, Codeine,

Dextromethorphan, temeril-P

Respiratory Drugs Bronchodilators- Causes bronchodilation

Four categories of drugs that cause bronchodilation Anticholinergics- used to treat bronchoconstriction

associated with organophosphate or carbamate toxicity. Glycopyrrolate, atropine

Antihistamines- Blocks effects of histamines used to treat allergic respiratory conditions Dyphenhydramine, Cetirizine, Hydroxyzine, Loratadine,

Cyproheptadine Beta-2 blockers-Combine with receptors on smooth muscle

fibers and relax the muscle Epinepherine, albuterol, terbutaline

Methylxanthines- Inhibits enzyme in smooth muscle, phosphodiesterase. Aminophylline, Theophylline

Cardiac Drugs Positive inotropic drugs- Improve the strength of contraction of heart.

Cardiac glycosides- rarely used due to adverse side effects. Catecholamines- epinepherine used during cardiac resuscitation and can be

used in anaphylaxis Inotrope mixed dilator- Pimobendan/vetmedin

Antiarrhythmic drug Class IA Depresses myocardial excitability, prolong refractory period,

decrease automaticity and increase conduction time Quinidine and procainamide

Class IB- Stabilizes the myocardial cell membranes. Blocks influx of Na preventing depolarization. Lidocaine

Class II Blocks Beta 1 receptor, may block beta 2 receptors also Propranolol, Atenolol

Class III limited use Class IV Calcium channel blockers depresses contraction

Diltiazam

Cardiac Drugs Vasodilator drugs- Dilate arteries or veins or

both. Decreases preload and after load on heart. Used to treat Congestive Heart Failure (CHF). Hydralazine, Nitroglycerin, Prazosin,

Angiotensin-converting enzyme Inhibitor (ACEI). Diuretics- Commonly used in treating CHF

Furosemide, Spironolactone (Potassium sparing)

Corticosteroids Mineralocorticoids- Aldosterone controls

electrolyte and water balance. Produced in zona glomerulosa of adrenal cortex.

Glucocorticoids- Cortisol. Produces anti-inflammatory and immunosuppresive effects. Produced in zona fasciculata of adrenal cortex. Decreased cortisol stimulates hypothalamus to

release corticotropin-releasing factor (CRF) to anterior pituitary which releases adrenocorticotropic hormone(ACTH) causing release of cortisol from adrenal cortex.

Corticosteroids Major Effects

Anti-inflammatory effects- By blocking phospholipase, blocking prostaglandin production. Prostaglandin major mediator of immune response.

Immunosuppressive effects- Inhibits antibody formation, decreasing lymphocytes and eosinophils

Corticosteroids Clinical uses

Anti-inflammatory Allergic reactions Autoimmune disease Shock Addison’s disease Some types of cancers

Side effects- PU/PD, Polyphagia, thinning of skin, muscle wasting gastric ulcers, delayed healing, Iatrogenic cushing’s.

Injectable products- Dexamethasone, Depo-medrol, Triamcinalone.

Oral products- Prednisone/prednisolone, Temaril-P.

Antiemetics/Gastrointestinal drugs Antiemetics

Metoclopramide/reglan- Acts centrally on CRTZ center blocking dopamine. Increases gastric emptying and Gastroesophageal

sphincter tone. Ondansteron/zofran and dolasteron/anzemet

Block serotonin receptors on vagal nerve and CRTZ Used commonly in patients receiving chemotherapy.

Maropitant citrate/cerenia- Blocks binding of substance P to NK-1 receptors and CRTZ. Parenteral or oral (Motion sickness)

Antiemetics/Gastrointestinal drugs Gastrointestinal medications

H2 antagonist- Cimetidine, ranitidine, Famotidine.

Proton pump inhibitors- Omeprazole Antacids- Maalox and Mylanta Gastromucosal protectants – Sucralfate/Carafate

Metronidazole/flagyl- Synthetic antibacterial/antiprotazoal. Used to treat giardia, trichomonas, IBD, Ulcerative

colitis and anaerobic infections.

Anticonvulsants Drugs that prevent or control seizures

Benzodiazapines Diazepam/valium- Treats seizures in progress 3-4 hours duration.

Can be given rectally to get seizure under control. Midazolam – Treat seizures in progress, administered IV.

Barbiturates Pentobarbital- Used to control seizures not responding to

Diazepam. Administered IV. Phenobarbital- Prevents and treats seizures. Most commonly

used! Administered oral or parenteral. Must regularly check blood levels and CBC, chemistry panel when administering.

Other Potassium bromide – Can use alone or in combination with

phenobarbital. Adjunctive medications- Clorazepate, Gabapentin, Levetircetam,

zonisamide.

Insulin Used to treat Diabetes Mellitus. Given SC in cases when DKA not present. DKA cases given as CRI or IM. Measured in units per milliliters.

U-40 animal approved products (prozinc and vetsulin) U-100 human approved products

Short acting- Humulin-R, Novolin. Used in DKA cases IV, IM or SC

Intermediate acting- NPH (Humulin-N), PZI(prozinc). Used to treat uncomplicated diabetes mellitus, SC only.

Long acting – Glargine(lantus), Detemir(levemir) Used to treat uncomplicated diabetes mellitus cases, SC.