Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Principles of Pharmacology Chapter 32

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc.

Principles of Pharmacology

Chapter 32

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Slide 2

Clinical Pharmacology

Study of the biologic effects of a drug on a patient and the actions of the drug over time

Medical assistants must understand:– Drug action

– Typical side effects

– Route of administration

– Recommended dose

– Individual patient factors that can alter the drug’s effect and elimination

Be prepared to provide safe drug therapy patient education.


Government Regulation

Several federal agencies regulate drugs in the United States.

FDA regulates development and sale of prescription drugs and OTCs.

– New drugs must gain FDA approval before release.

– Drug must pass tests starting in the laboratory on animals and then in human clinical trials.

– Drug must have acceptable benefit-to-risk ratio.

– Copyright awarded to pharmaceutical company for 17 years.

– FDA ensures generic brands are effective and safe.

DEA enforces federal laws designed to control drug abuse and also educates the public on drug-abuse prevention.

FTC regulates OTC advertisement.


Controlled Substances Act (CSA)

DEA enforces CSA regulations.

Drug that has potential for illegal use and abuse must be placed on controlled substance list.

Any new medication that has similar action to drug already on controlled list is automatically considered a controlled substance.

CSA divides controlled substances into five sections according to drug addictive abilities and potential for abuse.


Classification of Controlled Substances

Schedule I—No accepted medical use; illegal to possess. Examples: heroin, LSD, Quaalude, amphetamines.

Schedule II—Severe restrictions; high potential for abuse. Examples: morphine, cocaine, cannabis, Percodan.

Schedule III—Accepted use; moderate to low physical and high psychologic dependence. Examples: Tylenol with codeine, paregoric, anabolic steroids.

Schedule IV—Accepted for use; low potential for abuse. Examples: Librium, Valium, Darvon, Tranxene, Xanax.

Schedule V—Accepted for use; low potential for abuse; drug mixtures that contain limited amounts of narcotics.


Regulations for Management of Controlled Substances

Physician Controlled Substance Registration Certificate– DEA registration number must be included on all

prescriptions for controlled substances.– Renewable every 3 years and specific to site of practice.

Documentation– Number of doses dispensed and administered. – Count of doses on site before and after medication

dispensed.– Specific forms developed for this purpose.– Any discrepancy in drug count must be cosigned.

Record keeping

– Records maintained on purchase and use.– Kept separate from patient chart for 2 years.– Be readily available for DEA inspection.


Controlled Substance Regulations (cont’d)

Controlled substance disposal– Drug loss must be reported to DEA immediately.

– Drug disposal requires two employees to witness and document procedure (Critical Application p. 570).

– Contact DEA for guidelines on disposal of large amount.

Storage

– Immovable locked cabinet.

– Limited access to keys.

*MA must be aware of specific state regulations.


Controlled Substance Prescriptions Must be written in ink or typed.

Prescription must include name and address of patient; physician information including DEA number; amount prescribed, written out, and usually for small quantities; must be manually signed by the physician.

Orders for Schedule II drugs cannot be phoned in except in an absolute emergency, and written prescription must be delivered to pharmacy within 72 hr. Prescription cannot be refilled.

Schedule III, IV, and V drugs may be prescribed by phone or written and refilled up to five times in a 6-month period.

In some states Schedule V drugs can be dispensed by the pharmacist without a physician prescription.


Drug Abuse

Patients may misuse or abuse prescription, OTC, and illegal drugs.

Drug dependence—inability to function unless under the influence of the substance. Can have acute and chronic effects

Physical dependence (addiction)—biochemical changes within the body that require the substance to be used continuously in order for the person to function and to avoid physical discomfort

Psychologic dependence—compulsive craving for the substance

Habituation—mild form (caffeine)


Prevention of Drug Abuse

Monitor patients who repeatedly call for controlled substance prescription refills.

Request medical records for patients with history of controlled substance use.

Keep prescription pads in safe place.

Store limited amount of controlled substances in office.

Maintain complete and accurate records; keep patient records accurate and complete.


Drug Names

A single drug may have as many as three names: chemical, generic, and trade.

Chemical name is the drug’s formula.

Generic or official name is assigned to the drug and may reflect the chemical name. Is not protected by copyright law.

The trade or brand name is the name given the compound by the developing pharmaceutical company and is protected by copyright for 17 years.


Approaches to Studying Pharmacology

Using drug reference materials is crucial to the safe administration of medications.

Most drug reference books supply the action, indication, contraindications, precautions, adverse reactions, dosage, administration guidelines, and method of packaging.

The most frequently consulted drug reference guide is the PDR, but package inserts also can be used.


Learning about Drugs

Take opportunities to observe the use of drugs in patient care.

Concentrate on the most important drugs in each classification.

Learn about a drug’s primary action and use, then expand your knowledge to its other actions and uses.


Dispensing Drugs: Over-the-Counter Drugs

OTC drugs may interfere or interact with prescription drugs.

Gather information about OTC use at each office visit.

Patient education for safe use of OTCs:– Carefully read label and insert for use guidelines.

– Take only the recommended dose.

– Discard when expired.

– Inform the physician of OTC use.

– Be aware of OTC contraindications.

– Check with pharmacist if you have questions.


Dispensing Drugs: Prescription Drugs

Written order by a physician for the dispensing and administration of a drug for a particular patient.

Must be signed by a physician to be legal.

MA may phone in a prescription to a pharmacy, but the order must first be written down and reviewed by the physician for accuracy.

Phoned order must be documented on the patient chart as a record of the medication.

The MA may write a prescription dictated by the physician, but the physician must review and sign the prescription.


Sample Prescription


Six Parts of a Prescription

Superscription: Patient's name and address, the date, and the symbol Rx (for the Latin “recipe,” meaning “take”)

Inscription: Main part of the prescription; name of the drug, dosage form, and strength

Subscription: Directions for the pharmacist; size of each dose, amount to be dispensed, and the form of the drug such as tablets or capsules


Six Parts of a Prescription (cont’d)

Signature: Directions for the patient; usually preceded by the symbol Sig: (for the Latin “signa,” meaning “mark”). The physician writes instructions for the label that tell the patient how, when, and in what quantities to use the medication.

Refill information: May be regulated by federal law if drug is a controlled substance; must write number of times refill allowed.

Physician signature: Must include manual signature of physician and DEA number when indicated.


Drug Interactions with the Body: Pharmacokinetics

Study of the movement of drugs throughout the body

Four actions occur when a drug is taken:– Absorption

– Distribution

– Metabolism

– Excretion


Pharmacokinetic Terms

Absorption: How a drug is absorbed into the body's circulating fluids– May have local or systemic effect

– Rate of absorption depends on route of administration Oral—convenient, safe, relatively inexpensive

Some drugs can be destroyed by GI system Food slows absorption rate and may interfere with action Metabolism in liver may require higher oral dose Drug may require enteric coating to prevent

destruction or GI irritation Some drugs difficult to absorb through the GI mucosa


Pharmacokinetic Terms (cont’d)

Parenteral—Administration of drugs by injection– Administered directly into the bloodstream (IV) or into

tissues with rich blood supply

– Fastest acting route of administration (IV, IM, SC)

– Rate of absorption increased with massage at site

– Pharmaceutical preparation may prolong absorption (PenG)

Topical and mucous membrane absorption– Local or systemic effects

– Examples: suppositories, nasal sprays, transdermal patches, inhalants



Distribution: How a drug is transported from the site of administration

– Drugs attach to plasma proteins and are carried by bloodstream to target tissue

– Blood-brain barrier—functional barrier between brain cells and capillaries

Metabolism: How the drug is inactivated, including the time it takes for a drug to be detoxified and broken down into byproducts– Occurs in the liver for excretion in the kidneys

– Drug tolerance—liver destroys it so rapidly that doses must be increased continuously for same effect



Excretion: The route by which a drug is excreted, or eliminated, from the body and the amount of time such a process requires– Primarily eliminated by kidneys, also by exhalation,

milk glands, skin, and so on

– Drug half-life—time required for drug amount to be decreased by 50%

– Half-life used to determine frequency of medication administration to maintain therapeutic blood levels


Factors That Affect Drug Action

Body weight

Age

Sex

Time of day

Pathologic factors

Immune responses


Factors That Affect Drug Action (cont’d)

Psychologic factors

Tolerance

Accumulation

Idiosyncrasy

Drug-to-drug interactions– Antagonism—action of one drug decreases intensity

or shortens duration of action of another drug

– Synergism—a drug increases or prolongs action of another drug

– Potentiation—two differently acting drugs increase each other’s effects


Classifications of Drug Actions

Drugs are generally classified according to their actions on the body or according to the body system they affect.

May have multiple actions and therefore multiple classifications.


Adrenergic

Action: Constricts blood vessels, narrows the lumen of a vessel

Examples: Epinephrine, phenylephrine (Neo-Synephrine)

Primary use: Stops superficial bleeding, increases and sustains blood pressure, and relieves nasal congestion


Analgesic

Action: Lessens the sensory function of the brain

Examples: – Nonnarcotic—aspirin; acetaminophen (Tylenol);

ibuprofen (Advil, Motrin)

– Narcotic—meperidine (Demerol); hydrocodone (Vicodin); propoxyphene (Darvon)

Primary use: Pain relief


Anesthetic

Action: Produces insensibility to pain or the sensation of pain

Examples: Bupivacaine (Marcaine); lidocaine (Xylocaine)

Primary use: Local or general anesthesia


Antacid

Action: Decreases the acidity in the stomach

Examples: omeprazole (Prilosec); esomeprazole (Nexium); lansoprazole (Prevacid); pantoprazole (Protonix); magaldrate (Riopan); calcium carbonate (Maalox)

Primary use: Treatment of gastric hyperacidity


Antianxiety

Action: Reduces anxiety and tension

Examples: Chlordiazepoxide (Librium); diazepam (Valium); alprazolam (Xanax)

Primary use: Produces calmness and releases muscle tension


Antibiotic

Action: Kills or inhibits the growth of microorganisms

Examples: Cefaclor (Ceclor); tetracycline (Acromycin); amoxicillin (Augmentin)

Primary use: Treatment of bacterial invasions and infections


Anticholinergic

Action: Parasympathetic blocking agent, reduces spasm in smooth muscle

Examples: Scopolamine; atropine sulfate

Primary use: Dry secretions


Anticoagulant

Action: Delays or blocks the clotting of blood

Examples: Heparin; warfarin sodium (Coumadin)

Primary use: Prevention of blood clots


Antidepressant

Action: Treats depression

Examples: Fluoxetine (Prozac); imipramine pamoate (Tofranil); amitriptyline (Elavil)

Primary use: Mood elevator


Antiemetic

Action: Acts on hypothalamus center in the brain

Examples: Prochlorperazine (Compazine); trimethobenzamide (Tigan); metoclopramide (Reglan)

Primary use: Prevents and relieves nausea and vomiting


Antiepileptic (Anticonvulsant)

Action: Reduces excessive stimulation of the brain

Examples: Phenytoin (Dilantin); phenobarbital; carbamazepine (Tegretol)

Primary use: Epilepsy and other convulsive disorders


Antifungal

Action: Slows or retards the multiplication of fungi

Examples: Miconazole (Monistat); nystatin (Mycostatin); amphotericin B

Primary use: Treatment of systemic or local fungal infections


Antihistamine

Action: Counteracts the effects of histamine; may inhibit gastric secretions

Examples: Brompheniramine maleate (Dimetane); chlorpheniramine (Chlor-Trimeton); diphenhydramine (Benadryl); promethazine (Phenergan); cimetidine (Tagamet); ranitidine (Zantac)

Primary use: Relief of allergies; prevention of gastric ulcers


Antihypertensive

Action: Blocks nerve impulses that constrict arteries; or slows heart rate, decreasing contractility; or restricts the hormone aldosterone in the blood

Examples: Atenolol (Tenormin); doxazosin mesylate (Cardura); metoprolol (Lopressor); methyldopa (Aldomet)

Primary use: Reduces and controls blood pressure


Antiinflammatory

Action: Antiinflammatory or antirheumatic

Examples: – Nonsteroidal (NSAIDs): ibuprofen (Advil, Motrin);

naproxen (Naprosyn)

– Steroidal: dexamethasone (Decadron); prednisone (Cortisone)

Primary use: Treatment of arthritic and other inflammatory disorders


Antineoplastic

Action: Inhibits the development of and destroys cancerous cells

Examples: Interferon alfa-2a (Roferon-A); hydroxyurea (Hydrea); cyclophosphamide (Cytoxan); fluorouracil (Adrucil)

Primary use: Cancer chemotherapy


Antipruritic

Action: Relieve itching

Examples: Calamine lotion; hydrocortisone ointment; Benadryl

Primary use: Allergies or topical exposures that cause itching


Antipyretic

Action: Reduces body temperature

Examples: Aspirin, acetaminophen, ibuprofen

Primary use: Reduces fever


Antispasmodic

Action: Relieves or prevents spasms from musculoskeletal injury or inflammation

Examples: Methocarbamol (Robaxin); carisoprodol (Soma)

Primary use: Sport injuries


Antitussive (Cough Suppressant)

Action: Inhibits the cough center

Examples: – Narcotic: Codeine sulfate

– Nonnarcotic: Dextromethorphan (Romilar, Robitussin DM)

Primary use: Temporarily suppresses a nonproductive cough; reduces the thickness of secretions


Bronchodilator

Action: Relaxes the smooth muscle of the bronchi

Examples: Aminophylline (Aminophyllin); theophylline (Theo-Dur); epinephrine (Adrenalin, Sus-Phrine); albuterol (Ventolin, Proventil); isoproterenol (Isuprel)

Primary use: Treatment of asthma, bronchospasm; promotes bronchodilation


Cathartic (Laxative)

Action: Increases peristaltic activity of the large intestine

Examples: Magnesium hydroxide (milk of magnesia); bisacodyl (Dulcolax); casanthranol (Peri-Colace); psyllium hydrophilic muciloid (Metamucil)

Primary use: Increases and hastens bowel evacuation (defecation)


Contraceptive

Action: Inhibits conception

Examples: Medroxyprogesterone acetate (Depo-Provera); norgestrel (Ovrett); ethinyl estradiol and ethynodiol diacetate (Demulen 1/35)

Primary use: Family planning


Decongestant

Action: Relieves local congestion in the tissues

Examples: Ephedrine or phenylephrine (Neo-Synephrine); pseudoephedrine (Sudafed); oxymetazoline (Afrin)

Primary use: Relief of nasal and sinus congestion caused by common cold, hay fever, or upper respiratory tract disorders


Diuretic

Action: Inhibits the reabsorption of sodium and chloride in the kidneys

Examples: Hydrochlorothiazide (Dyazide, Esidrix, HydroDiuril); furosemide (Lasix); triamterene (Dyrenium)

Primary use: Increases urinary output, decreases blood pressure


Expectorant

Action: Increases secretions and mucus from the bronchial tubes

Examples: Diphenhydramine (Benylin); guaifenesin guaiacolate (Fenesin, Robitussin)

Primary use: Upper respiratory tract congestion


Hemostatic

Action: Controls bleeding, a blood coagulant

Examples: Phytonadione, vitamin K (Konakion); absorbable hemostatics, such as Gelfoam and Surgicel, are applied directly to a wound

Primary use: Control of acute or chronic blood-clotting disorder; formation of absorbable, artificial clot


Hematopoietic

Action: Promotes red blood cell production

Examples: Epoetin alfa (Epogen, Procrit)

Primary use: Treatment of anemia in chemotherapy patients


Hypnotic (Sedative)

Action: Induces sleep and lessens the activity of the brain

Examples: Secobarbital (Seconal); flurazepam (Dalmane); temazepam (Restoril)

Primary use: Insomnia; lower doses sedate


Hormone Replacement

Action: Replaces hormones or compensates for hormone deficiency

Examples: Insulin (Humulin); levothyroxine sodium (Synthroid); estrogen (Premarin)

Primary use: Maintenance of adequate hormone levels


Lipid-Lowering

Action: Decreases blood cholesterol levels and/or increases HDL levels

Examples: Atorvastatin calcium (Lipitor); simvastatin (Zocor)

Primary use: Management of high blood cholesterol


Miotic

Action: Causes the pupil of the eye to constrict

Examples: Carbachol (Isopto Carbachol); isoflurophate (Floropryl); pilocarpine (Isopto Carpine)

Primary use: Counteracts pupil dilation


Mydriatic (Anticholinergic)

Action: Dilates the pupil of the eye

Examples: Atropine sulfate (Isopto Atropine)

Primary use: Ophthalmologic examinations


Narcotic

Action: Depresses the central nervous system and causes insensibility or stupor

Examples: – Natural narcotics: opium group (codeine phosphate,

morphine sulfate)

– Synthetic narcotics: meperidine (Demerol), methadone (Dolophine), and propoxyphene hydrochloride (Darvon)

Primary use: Pain relief


Oral Hypoglycemic

Action: Decreases blood glucose levels by increasing insulin production and/or decreasing target cell resistance to insulin or by delaying glucose absorption

Examples: Metformin hydrochloride (Glucophage); acarbose (Precose); chlorpropamide (Diabinese); glimepiride (Amaryl); glipizide (Glucotrol); glyburide (Micronase)

Primary use: Management of Type 2 diabetes mellitus


Osteoporosis Treatment

Action: Inhibits bone reabsorption and/or promotes usage of calcium

Examples: Alendronate (Fosamax); calcitonin (Miacalcin nasal spray and Calcimar); dihydrotachysterol; etidronate (Didronel)

Primary use: To promote bone mineral density and reverse the progression of osteoporosis


Patient Education: Interactions

Monitor for pregnancy.

Question drug allergies each office visit.

Observe patient for 20 minutes after drug administration.

Educate patient on possible drug side effects.

Educate patient on dose, time of administration, and drug storage.

Question patient on whether medication is being taken as ordered.

Answer questions or consult the physician.

Documents

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Principles of Pharmacology Chapter 32