PHARMACOLOGY - Introduction

DRUG ACTION:Pharmaceutic, Pharmacokinetic & Pharmacodynamic Phases

A. Pharmaceutic Phase - is the first phase of drug action

• The first phase of drug action• Drug becomes a solution so that it can be

absorbed2 Pharmaceutic phases: Disintegration & DissolutionDisintegration – is the breakdown of a tablet/capsule into smaller particlesDissolution – is the dissolving of the smaller particles in the GI fluid before absorption

- Drugs in liquid form are more rapidly available for GI absorption than are solids

- Enteric-coated drugs resist disintegration in the gastric acid of the stomach, so disintegration does not occur until the drug reaches the alkaline environment of the small intestine (enteric-coated tablets or capsules and sustained release capsules should not be crush, crushing would alter the place and time of absorption of the drug

B. Pharmacokinetic Phase • The of drug movement to achieve drug

actionThe Process are: ABSORPTION, DISTRIBUTION, METABOLISM (BIOTRANSFORMATION) & EXCRETION

ABSORPTION• Is the movement of drug particles from the

GI tract to body fluids by passive absorption, active absorption, or Pinocytosis

• Most oral drugs are absorbed into the surface area of the small instestine through the action of extensive mucosal villi

• Passive absorption – occurs mostly by diffusion (movement from higher concentration to lower concentration)

• Active absorption – requires a carrier such as enzyme or protein to move the drug against a concentration agent (energy is required for active absorption)

• Pinocytosis – is a process by which cells carry a drug across their membrane by engulfing the drug particles

FACTORS AFFECTING ABSORPTION• BLOOD FLOW – poor circulation as a result

of shock, vasoconstrictor drugs, or disease hampers absorption

• PAIN, STRESS & FOODS – slows gastric emptying time, so the drug remains in the stomach longer

• EXERCISE – decreases blood flow by causing more blood to flow to the peripheral muscle, thereby decreasing blood circulation to the GI tract

• BLOOD SUPPLY – drugs given IM are absorbed faster in muscles that have more blood vessels (e.g. deltoids) than in those that have fewer blood vessels (gluteals)

• FIRST PASS EFFECT – the process in which the drug passes to the liver first, metabolizing the drug to an active form

• BIOAVAILABILITY – is the percentage of the administered drug dose that reaches the systemic circulation (less than 100% for oral route, 100% for IV route)

Factors Affecting Bioavailability:a. The drug form (tablet, capsule, sustained

release, liquid, transdermal patch, inhalation)

b. Route of administration c. GI mucosa and motilityd. Food and other drugse. Changes in the liver metabolism caused by

liver dysfunction or inadequate hepatic blood flow (a decrease in liver function or a decrease in hepatic blood flow can increase the bioavailability of a drug)

DISTRIBUTION• The process by which the drug becomes

available to body fluids and body tissues• Influenced by blood flow, drug’s affinity to

the tissue and the protein-binding effect• Protein binding capability - Drugs that

binds to a carrier protein (albumin) is pharmacologically becomes inactive

• Only “free drugs” (drugs not bound to protein) are active and can cause pharmacologic response

• Highly protein bound drugs - drugs that are greater than 89% bound to protein e.g. diazepam, digitoxin, furosemide, propanolol, rifampin

• Moderately-Highly protein drugs – drugs that are 61% to 89% bound to protein e.g. erythromycin, quinidine, trimethoprim

• Moderately Protein bound drugs – drugs that are 30-60% bound to protein e.g. aspirin, lidocaine, meperidine, theophylline

• Low protein bound drugs – less than 30% bound to protein e.g. amikacin, amoxicillin,cephalexin, digoxin, terbutaline sulfate, neostigmine bromide

Note: clients with liver or kidney disease or those who are malnourished may have an abnormally low serum albumin level (this results in fewer protein-binding sites, which in turn leads to excess free drug and eventually to drug toxicity)

METABOLISM• Aka. “Biotransformation”• The process by which a drugs are

inactivated by liver enzymes and are then converted into inactive metabolites or water soluble substances for Excretion

• The liver is the primary site of metabolism• Decreased rate of drug metabolism

(cirrhosis/hepatitis) will cause excess drug accumulation leading to drug toxicity

• HALF LIFE – is the time it takes for one half of the drug concentration to be eliminated

Note: knowing the half-life, the time it takes for a drug to reach a steady state of serum concentration can be computed

e.g. Half-life of 650 mg of AspirinTime of elimination (hr)

Dosages Remaining (mg)

Percentage Left (%)

3 325 50 6 162 25 9 81 12.5

12 40 6.25 15 20 3.1 18 10 1.55

EXCRETION• Refers to the elimination of drugs from the

body• KIDNEY – is the main route of drug

elimination • Other routes: hepatic metabolism, bile,

feces, lungs, saliva, sweat & breast milk• Protein-bound drugs cannot be filtered

through the kidneys, once the drug is released from the protein, it is a free drug and is eventually excreted in the urine

Factors affecting Excretion• Urine pH – urine pH ranging from 4.5 to 8.

Acid urine promotes elimination of weak base drugs and alkaline urine promotes elimination of weak acid drugs (aspirin)

• Kidney disease that results in decreased glomerular filtration rate (GFR) or decreased renal tubular secretion (drug excretion is slowed or impaired)

• A decreased in blood flow to the kidneys can alter drug excretion

Note: the most accurate test to determine renal function is Creatinine Clearance. Creatinine is a metabolic byproduct of muscle that is excreted by the kidneys. Lower values are expected in elderly and female clients because of their decreased muscle mass. A decrease in renal GFR results in an increase in serum creatinine level and a decrease in urine creatinine clearance. (Normal value is 85-135 ml/min)

C. Pharmacodynamic Phase • Is the study of drug concentration and its

effects on the body• Drug response can cause a primary or

secondary physiologic effect or both• E.g. Diphenhydramine (Benadryl) –

antihistamine, primary effect is treat symptoms of allergy, secondary effect – CNS depression that causes drowsiness

ONSET, PEAK & DURATION of Action• ONSET OF ACTION – is the time it takes to

reach the minimum effective concentration after a drug is administered

• PEAK ACTION – occurs when the drug reaches its highest blood or plasma concentration

• DURATION OF ACTION – is the length of time the drug has a pharmacologic effect

Receptor Theory- Most receptors, protein in structure are

found on cell membranes- Drugs act through receptors by binding to

the receptor to produce (initiate) a response or to block (prevent) a response.

- The activity of many drugs is determined by the ability of the drug to bind to a specific receptor, “the better the drug fits at the receptor site, the more biologically active the drug is” (similar to lock and key concept)

AGONISTS & ANTAGONISTS• AGONISTS – drugs that produce a

response• ANTAGONISTS – drugs that block a

response• E.g. Isoproterenol (Isuprel) simulates the

beta 1 receptor (agonist), Cimetidine (Tagamet), an antagonist, blocks the histamine (H2) receptor, thus preventing excessive gastric acid secretion

THERAPEUTIC INDEX • Therapeutic Index (TI) – estimates the

margin of safety of a drug through the use

of a ratio that measures the effective (therapeutic) dose and lethal dose

• LOW THERAPEUTIC INDEX – have a narrow margin of safety, drug levels need to be monitored because of small safety range

• HIGH THERAPEUTIC INDEX – have a wide margin of safety and less danger of producing toxic effects, drugs do not need to monitored routinely

Important Terms:LOADING DOSE – a large initial dose to initiate immediate drug responseSIDE EFFECTS – are physiologic effects not related to desired drug effectsADVERSE REACTIONS – are more severe than side effects, undesirable effects of drugs that cause mild to severe side effectsTOXIC EFFECTS or TOXICITY – drug level exceeds the therapeutic range resulting from overdosing or drug accumulationTOLERANCE – refers to a decreased responsiveness over the course of therapyPLACEBO EFFECT – is a psychologic benefit from a compound that may not have the chemical structure of a drug effectDRUG-DRUG INTERACTION – the effects of a combination of drugs may be greater than, equal to, or less than the effects of a single drugFOOD-DRUG INTERACTION – the effects of selected foods may speed, delay or prevent absorption of specific drugs

PRINCIPLES OF DRUG ADMINISTRATION- Administration of medications is a basic

activity in nursing practice- Nurses must be knowledgeable about the

specific drugs and their administration, client response, drug interactions, client allergies

- Nurses are accountable for the safe administration of medications

- Nurses must know all the components of a drug order and questions those orders that are not complete, unclear, outside the recommended range,

- Nurses are legally liable if they give a prescribed drug and the dosage is incorrect or the drug is contraindicated for the client

The “Five-Plus-Five Rights” of Drug Administration

• To provide safe drug administration, the nurse should practice the “Rights” of drug administration

1. RIGHT CLIENT- Verify client by checking the identification

band

- Distinguish between two clients with the same last name

2. RIGHT DRUG – means that the client receives the drug that was prescribed

- A telephone order or verbal order for medication must be cosigned by the prescribing health care provider within 24 hours

Components of a Drug Order:a. Date and timeb. Drug namec. Drug dosaged. Route of administratione. Frequency and duration of

administrationf. Any special instructionsg. Physician or other health care provider’s

signature

Four (4) main categories of drug orders:1. Standing – an ongoing order or may be

given for a specific number of doses or days e.g. Digoxin 0.25 mg PO daily

2. One-time or Single orders – given once and usually at a specific time e.g. Diazepam 5mg IV before surgery

3. PRN orders – given at the client’s request and nurse’s judgment e.g. Tylenol 650mg q3 to 4h PRN for headache

4. STAT orders – given once, immediately e.g. Morphine sulfate 2mg IV STAT

3. RIGHT DOSE – is the dose prescribed for a particular client

- Nurses must calculate each drug dose accurately

- Before calculating a drug dose, the nurse should have a general idea of the answer based on knowledge of the basic formula or ratios or proportions

4. RIGHT TIME – is the time at which the prescribed dose should be administered

- Administer drugs at the specified times. Drugs may be given 30 minutes before or after the time prescribed if the administration interval is >2hours

- Administer drugs that are affected by foods before meals

- Administer drugs that can irritate the stomach (gastric mucosa) with food

5. RIGHT ROUTE – is necessary for adequate or appropriate absorption

- The more common routes are oral, sublingual (under tongue for venous absorption), buccal (between gum and cheek), inhalation (aerosol sprays),

suppository (rectal, vaginal) & parenteral (ID, SC, IM, IV)

- Assess the client’s ability to swallow before the administration of oral medications

- Do not crush or mix medication in other substances before consultation

- Use aseptic technique when administering drugs. Sterile technique is required with the parenteral routes

- Stay with the client until oral drugs have been swallowed

6. RIGHT ASSESSMENT – requires that appropriate data be collected before administration of the drug e.g. taking apical HR before administration of digitalis preparations or serum blood sugar levels before the administration of insulin

7. RIGHT DOCUMENTATION – requires that the nurses immediately record the appropriate information about the drug administeredThis includes:

- Name of the drug- Dose- Route- Time and date- Nurse’s initials or signature

8. RIGHT TO EDUCATION – requires that clients receive accurate and thorough information about the medication and how it relates to their particular situation including therapeutic purpose, possible side effects, dietary restrictions

9. RIGHT EVALUATION – requires that the effectiveness of the medication be determined by the client’s response to the medication

10. RIGHT TO REFUSE – client can and do refuse to take a medication, it is the nurse’s responsibility to determine when possible the reason for the refusal and to take reasonable measures to facilitate the client’s taking the medication and reinforce the reason for the medication

FORMS & ROUTES FOR DRUG ADMINSTRATIONTablets & Capsules

• Oral medications are not given to clients who are vomiting, lack of a gag reflex or who are comatose

• Administer irritating drugs with food to decrease GI discomfort

• Administer drugs on empty stomach if food interferes with medication absorption

• Drugs given sublingually or buccally remain in place until fully absorbed, no fluids should be taken while the medication is in place

Liquids- Several forms of liquid medication including

elixirs (sweetened, hydroalcoholic liquid), emusions (mixture of two liquids that are not mutually soluble) and suspensions (particles are mixed with but not dissolve in another fluid)

- Read labels to determine whether dilution or shaking is required

- The meniscus is at the line of the desired dose

Transdermal • Transdermal medication is stored in a patch

laced on the skin and absorbed through skin, thereby having systemic effect

• Transdermal patches should be rotated to different sites and not reapplied over the next exact same area when changed

• The area should be thoroughly cleaned prior to administration of a new transdermal patch

Topical• Topical medication can be applied to the

skin with glove, tongue blade or cotton-tipped applicator

• Use appropriate technique to remove the medication from the container and apply it to the clean, dry skin

InstillationsAdministration of Eye Drops

• Remove any discharge by gently wiping out from inner canthus. Use separate cloth for each eye

• Gently draw the skin down below the affected eye to expose the conjunctival sac

• Administer the prescribed number of drops into the center of the sac (not directly on the cornea)

• Gently press on the lacrimal duct with sterile cotton ball or tissue for 1-2 min. after instillation to prevent systemic absorption

• Client should keep eyes closed for 1-2 min. to promote absorption

Administration of Eardrops• Medication should be at room temperature• Client should sit up with head tilted slightly

toward the unaffected side• CHILD: pull down and back on auricle.

AFTER 3 YEARS OF AGE/ADULT: pull up and back on auricle

• Instill prescribed number of drops

• Have client maintain position for 2-3 min

Administration of Nose Drops & Sprays- Have the client blow the nose• Have the client tilt head back for drops to

reach frontal sinus and tilt head to affected side to reach ethmoid sinus

• Have the client keep head tilted backward for 5 minutes after instillation

Nasogastric and Gastrotomy Tubes- Check for proper placement of tube- Pour drug into syringe without plunger or

bulb, release clamp and allow medication to flow in properly, usually by gravity

- Flush tubing with 50 ml of water- Clamp the tube and remove syringe

SUPPOSITORIESRectal Suppositories

• Suppositories tend to soften at room temperature and therefore need to be refrigerated

• Use a glove for insertion• Instruct the client to lie on left side and

breath through the mouth to relax the anal sphincter

• Apply a small amount of water-soluble lubricant to the tip and gently insert the suppository beyond the internal sphincter

• Have the client remain lying on the side for 20 min after instillation

Vaginal Suppositories • Generally inserted into the vagina with an

applicator • Wear gloves• The client should be in the lithotomy

position

PARENTERALIntradermal

• Local effect• Used for observation of an inflammatory

(allergic) reaction to foreign proteins e.g. tuberculin testing, testing for drug sensitivities

• Site: lightly pigmented, hairless such as ventral midforarm, clavicular area of the chest & scapular area of the back

• Equipment: 25-27 gauge, 3/8 to 5/8 inches in length, 1ml syringe

• Insert the needle bevel up, at a 10-15 degree angle

• Inject medication slowly to form a wheal (bleb)

• Do not massage the area

• Assess for allergic reaction in 24 to 72 hours (measure the diameter of local reaction)

Subcutaneous • Systemic effect• Sites: abdomen, upper hips, upper back,

lateral upper arms and lateral thighs• Sites should be rotated with subcutaneous

injections i.e. Insulin & Heparin• Equipment: 25-27 gauge, ½ to 5/8 inches in

length, 1-3 ml syringe (usually 0.5-1.5 ml is injected)

• Insert the needle at an angle appropriate to body size: 45 to 90 degrees

• Aspirate except heparin & Insulin• Gently massage the area unless

contraindicated, as with heparin & Insulin • Apply gentle pressure to the injection site to

prevent bleeding into the tissue

Intramuscular • Systemic effect• Usually more rapid effect of drug than with

SQ• Sites: Ventrogluteal, Dorsogluteal, Deltoid

and Vastus Lateralis (pediatrics)• Equipment: 20-23 gauge, 18 g for blood

transfusion, 1-1.5 inches in length• Flatten the skin area using the thumb and

index finger and inject between them• Insert the needle at 90 degree angle• Ventrogluteal site – volume of drug

administration is 1-3ml (slightly angle the needle toward the iliac crest)

• Dorsogluteal site - volume of drug administration is 1-3ml, place the needle at a 90 degree angle to the skin with the client prone

• Deltoid site - volume of drug administration is 0.5 to 1ml, place the needle at a 90 degree angle to the skin or slightly toward acromion

• Vastus lateralis - volume of drug administration is less than 0.5ml in infants, 1 ml in pediatrics, 1-1.5 ml in adults (direct the needle at the knee at 45 to 60 degree angle to the lateral middle thigh)

Z-Tract Injection technique • Prevents the medication from leaking back

into the subQ tissue• Used for medications that cause visible

permanent skin discolorations (e.g. iron dextran)

• Gluteal site is preferredSTEPS:

• a. pull the skin to one side and hold• b. insert needle

• c. Hold skin to side• d. inject medication

Intravenous• Systemic effect• More rapid than the IM or subQ routes• Site: accessible peripheral veins such as

cephalic vein of the arm, dorsal vein of hand for direct IV

• Equipment: adults 20-21 gauge 1-1.5 inches, infants 24 gauge 1 inch

DRUGS FOR NEUROMUSCULAR DISORDERS: Myasthenia Gravis, Muscle Spasm

Myasthenia Gravis (MG) – a lack of nerve impulses and muscle responses at the myoneural

(nerve muscle endings) junction, causes fatigue and muscular weakness of the respiratory system, facial muscles and extremities, ptosis (early symptoms), difficulty in chewing and swallowing (dysphagia)

- Results from a lack of acetylcholine receptor sites

- Group of drugs used to control MG is the AChE inhibitors (aka. Cholinesterase inhibitors & anticholinesterase) which inhibits the action of enzyme and more acetylcholine is available to activate the cholinergic receptors and promote muscle contraction

- Myasthenic crisis – severe generalized muscle weakness and involve muscles of respiration due to inadequate dosing of AChE inhibitors

- Cholinergic crisis – an acute exacerbations of symptoms of MG resulting from overdosing with AChE inhibitors manifested as severe muscle weakness that can lead to respiratory paralysis

Acetylcholinesterase Inhibitors or Cholinesterase InhibitorsPrototypes:

- Neostigmine (Prostigmine) - first drug used to manage MG, a short-acting acetylcholinesterase inhibitor with a half-life of 0.5 to 1 hour (given every 2-4 hours on time to prevent muscle weakness)

- Pyridostigmine bromide (Mestinon) – has an intermediate action and given every 3-6 hours

- Edrophonium CL (Tensilon) – for diagnosing myasthenia gravis, ptosis should be absent in 1-5 min. increase muscle strength for 5-20 min.

Mode of action: transmission of neuromuscular impulses by preventing destruction of acetylcholine, increasing muscle strengthSide effects/ Adverse reaction: GI disturbances (nausea/vomiting, diarrhea, abdominal cramps), increased salivation and tearingUnderdosing – myasthenia crisis (muscle weakness)Overdosing – cholinergic crisis (severe muscle weakness, dyspnea)

Nursing interventions (Acetylcholinesterase Inhibitors)

1. Monitor effectiveness of drug therapy – muscle strength should be increased

2. Observe client for signs and symptoms of cholinergic crisis caused by overdosing i.e. severe muscle weakness, increased salivation, sweating, tearing

3. Have readily available antidote for cholinergic crisis (atropine sulfate)

4. All doses of AChE inhibitors should be administered ON TIME, because late administration of the drug could result in muscle weakness

SKELETAL MUSCLE RELAXANTS- Muscle relaxants relieve muscular spasms

and pain associated with traumatic injuries and spasticity

- Skeletal muscle Spasticity – is muscular hyperactivity that causes contraction of the muscles resulting in pain and limited mobility

- Muscle spasms - have various causes including injury or motor neuron disorders that lead to conditions such as cerebral palsy, spinal cord injuries, CVA which causes pain and limited ROM mobility

Prototype:Muscle Relaxants

1. Baclofen (Lioresal) – for muscle spasms caused by multiple sclerosis and spinal cord injury, overdose can cause CNS depression, drowsiness, dizziness, hypertension

2. Dantrolene sodium (Dantrium) – for chronic neurologic disorders causing spasm i.e. SCI, stroke, avoid taking with alcohol and CNS depression

3. Pancronium bromide (Pavulon) – used in surgery for relaxation of skeletal muscle

4. Succinylcholine CL (Anectine) – used in surgery with anesthesia for skeletal muscle relaxation

Side effects/Adverse Reactions:Nausea, vomiting, dizziness, weakness, insomnia, tachycardia, hypotension

Nursing Interventions (Muscle relaxants)1. Monitor and report elevated liver enzymes2. Observe for CNS side effects i.e. dizziness3. Instruct client not to abruptly stop taking

muscle relaxant to avoid rebound spasms4. Advise client not to drive or operate

dangerous machinery because of sedative effect of drug i.e. drowsiness

5. Teach client to avoid alcohol and CNS depressants

6. Contraindicated for pregnant mothers

ANTIDYSRHYTHMIC DRUGSCardiac Dysrhythmias (arrhythmia)

Defined as any deviation from the normal rate or pattern of the heartbeat, includes

heart rates that are too slow (bradycardia), too fast (tachycardia) or irregular.

The terms dysrhythmia (disturbed heart rhythm) and arrhythmia (absence of heart rhythm) are used interchangeably

Frequently follow an MI or can result from hypoxia, hypercapnia (increased CO2 in the blood), coronary artery disease, excess cathecolamines or electrolyte imbalance

MOA: is to restore the cardiac rhythm to normal

Classes and Actions of Antidysrhythmic drugsCLASS I – Sodium Channel Blockers1. Sodium Channel Blocker IA

Slow conduction and prolong repolarization Indicated for atrial and ventricular

dysrhytmias, paroxysmal atrial tachychardiaPrototype:Disopyramide phosphate (Norpace) – prevention and suppression of unifocal and multifocal premature ventricular contractions (PVC), may cause anticholinergic symptomsProcainamide HCL (Procanbid) – controls dysrhythmias (PVC’s), ventricular tachycardia, depresses myocardial excitability by slowing down conductivity of cardiac tissueQuinidine sulfate (Quinidex) – for atrial, ventricular dysrhythmias. nausea, vomiting, diarrhea, abdominal pain or cramps are common discomfort

2. Sodium Channel Blocker IB Slow conduction and shorten repolarization Indicated for acute ventricular dysrhythmia

Prototype:Lidocaine (xylocaine) – for acute ventricular dysrhtymia following MI and cardiac surgeryMexiletine HCL (Mexitil) – analogue of lidocaine. Treatment for acute and chronic ventricular dysrhytmias. Take with food to decrease GI discomfort. Common side effects are nausea/vomiting, heartburn, tremor, dizziness, nervousness, lightheadedness

3. Sodium Channel Blocker IC Prolong conduction with little to no effect on

repolarozation Indicated for life-threatening ventricular

dysrhythmiasPrototype:Flecainide (Tambocor) – for life-threatening ventricular dysrhytmias, prevention of paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation or flutter (PAF), contraindicated for cardiogenic shock and second or third heart block

CLASS II - Beta Blockers

Reduce calcium entry Decrease conduction velocity, automaticity Indicated for atrial flutter and fibrillation,

tachydysrhythmias, ventricular and supraventricular dysrhythmias

Prototype:Acebutol HCL (Sectral) –beta 1 blocker, management of ventricular dysrhytmias. Also used for angina pectoris and hypertension, primarily for PVC’s, affects beta1 receptors (side effects: bradycardia and decrease cardiac output)Esmolol (Brevibloc) – beta 1 blocker, control atrial flutter and fibrillation, short time used only, mainly for clients having dysrhythmia during surgeryPropanolol HCL (Inderal) – beta 1 and beta 2 blocker, for ventricular dysrhythmias, PAT and atrial and ventricular ectopic beats, contraindicated for clients with asthma

CLASS III – Drugs that prolong Repolarization Prolong repolarization during ventricular

dysrhthmias Prolong action potential duration Indicated for life-threatening atrial and

ventricular dysrhythmias resistant to other drugs

Prototype:Adenosine (Adenocard) – treatment of PSVT. Avoid if second or third degree AV block or atrial flutter or fibrillation is presentAmiodarone HCL (Cordarone) – for life-threatening ventricular dysrhytmias, initial dose and greater then decrease over timeBretylium tosylate (Bretylol) – for ventricular tachycardia and fibrillation, used when lidocaine and procainamide are ineffective

CLASS IV – Calcium Channel Blockers Block calcium influx, Slow conduction

velocity ,Decrease myocardial contractility Indicated for supraventricular

tachydysrhytmias, prevention of paroxysmal supraventricular tachycardia (PSVT)

Prototype:Verapamil HCL (Calan, Isoptin) – for supraventricular tachydysrhythmias, prevention of pSVT. Also used for angina pectoris and hypertension, avoiduseif cardiogenic shock, second or third degree AV block, severe hypotension occurDiltiazem (Cardizem) – for PSVT and atrial flutter or fibrillation, avoid use if second or third degree AV block or hypotension occur

Nursing Interventions (Antidysrhythmics)1. Monitor ECG for abnormal patterns and

report findings i.e. premature ventricular contractions

2. Instruct client to report side effect/adverse reactions i.e. dizziness, faintness, nausea and vomiting

3. Advise client to avoid alcohol and tobacco. (Alcohol can intensify the hypotensive reaction, caffeine increases the cathecolamine level and tobacco promotes vasoconstriction)

ADDITIONAL Miscellaneous Drugs:LOW-MOLECULAR-WEIGHT HEPARINS (LMWH)

An extract from the fraction of a standard heparin with an equivalent anticoagulant effect but lower risk for bleeding and produces more stable responses at recommended doses

Derivatives of standard heparin introduced to prevent venous thromboembolism

Frequent laboratory monitoring of APTT is not required because LMWH does not have the standard of heparin

Prototype:Dalteparin sodium (Fragmin) – for prevention of DVT before surgey and for those at risk of thromboembolismEnoxaparin sodium (Lovenox) – for thromboembolism. Prevents and treats DVT and pulmonary embolism (bleeding is an adverse reaction)

ANTIEMETICS Antivomiting agents1. Dopamine Antagonists – suppress emesis

by blocking dopamine2 receptors in the CTZ (chemotherapeutic trigger zone – lies near the medulla and the vomiting center in the medulla causes vomiting when stimulated)

- Common side effects: extrapyramidal symptoms (EPS) – caused by blocking dopamine receptors and hypotensionPrototype:PhenothiazinesProchlorperazine maleate (Compazine) & promethazine (Phenergan)– for severe nausea and vomiting (primary use), reduce anxiety and tension (secondary use), side effects: drowsiness, dizziness and dry mouth

2. Metoclopramide HCL (Reglan) – suppresses nausea &emesis (vomiting) by blocking the dopamine receptors in the CTZ, used in the treatment of postoperative emesis, cancer chemotherapy and radiation therapy (increases gastric and intestinal emptying)

Bethanechol (Duvoid, Urecholine) Primarily act directly on muscarinic

acetylcholine receptors

Facilitate contraction of detrusor muscle of the urinary bladder

Indication Postoperative or postpartum urinary

retention Neurogenic atony of the bladder with

retention

LAXATIVES Used only after the client does not

adequately respond to other nonpharmacologic interventions such as a high fiber diet and increase fluids

TypesA. Stool Softeners or Surfactant Laxatives

Mildest form of cathartic Detergent action lowers surface

tension, allowing water and fats to enter and soften stool

Used especially for clients who should avoid straining

Prototype: Docusate sodium (Colace)Docusate calcium (Surfak)Docusate with casanthranol (Peri-Colace) is a stool softener combined with a stimulant

Adverse effects: Diarrhea and mild cramps

ANTIDIARRHEALS Inhibit peristaltic activity by direct action on

intestinal muscles Inhibit receptors responsible for peristalsis

Prototype: Kaolin and pectin (Kaopectate) Loperamide (Immodium) Diphenoxylate hydrochloride with atropine

sulfate (Lomotil) Paregoric (camphorated opium tincture) Bismuth subsalicylate (Pepto-Bismol)

Adverse effects: Nausea, vomiting, anorexia, abdominal

cramping, diarrhea, mild cramps Headache, dizziness, drowsiness Pruritus, rash

EMETICS Active ingredient is emetine which

stimulates the vomiting reflex located in the medulla by stimulating the chemoreceptor trigger zone and irritating gastric mucosa

1. Syrup of Ipecac used for accidental poisoning Currently being abused by clients

with bulimia nervosa Fatal dose is 10-25 mg

Emetine is secreted slowly so a daily dose of 30 ml is toxic and fatal after several months

Recommended dose Children < 1 yr: 5-10 ml followed by ½ to 1

glass of water Children over 1 year old: 15 ml followed by

1-2 glasses of water Adults: 30 ml followed by 3-4 glasses of

water Vomiting generally occurs within 20 minutes

or dose may be repeated Contraindications & precautions

Unconscious client Pregnancy Lactation Poisoning from caustic substances such as

gasoline, kerosene Nursing interventions

Assess vital signs before administration Obtain ECG before administration Instruct to keep syrup of ipecac in a safe

locked location Avoid giving with milk products because

they delay the emesis Avoid giving with carbonated beverages

because they increase abdominal distention

2. Activated Charcoal Binds and inactivates the poison

until excreted Recommended to give as soon as

possible after ingestion of poisoning but not within 1-2 hours of syrup of ipecac

Given as a powder prepared in an aqueous slurry to absorb the poison

Recommended dose Children: not more than 1 dose Adults: 30-100 mg

Adverse effect Black tarry stools, diarrhea, constipation

Contraindications & precautions Unconscious client Pregnancy Lactation Poisoning from caustic substances such as

cyanide Nursing interventions

Avoid giving within 1-2 hours after ingestion of syrup of ipecac

Assess vital signs before administration May give with a laxative to promote

elimination

INSULIN, ANTIDIABETIC AGENTS & GLUCAGON

Insulin is produced by the beta cells in the Islets of Langerhans in the pancreas

Key role in the metabolism of CHO, CHOO, CHON

Glucagon is secreted by the alpha cells from the Islets of Langerhans in the pancreas and stimulates hepatic production of glucose from glycogen stores

MOA of Insulin: Stimulates the active transport of glucose

into muscle and adipose tissue cells Regulates the rate at which carbohydrates

are burned by the cells for energy Promotes the conversion of glucose to

glycogen for storage in the liver Promotes the conversion of fatty acids into

fat which can be stored as adipose tissue Promotes conversion of amino acids to

proteins in muscle Promotes intracellular shifts of K and Mg

Indications Hormone replacement in the treatment of

DM type 1 and are unable to produce insulin Antidiabetic agents are used in the

treatment of DM type 2 and who produce an insufficient amount of insulin

Glucagon, a hyperglycemic agent, is used in the acute management of severe hypoglycemia when administration of glucose is not feasible

Adverse reactions of insulin Hypoglycemia Coma Lipoatrophy and lipohypertrophy of the

injection site Local allergic reaction at the injection site Insulin resistance Allergic reaction

Nursing interventions Monitor blood glucose frequently when

therapy is initiated and routinely when stabilized

Monitor for hypoglycemia at peak time of insulin e.g. apprehension, chills, perspiration, confusion, double vision, drowsiness, inability to concentrate, shakiness, nausea, rapid pulse

Monitor for hyperglycemia e.g. flushed skin, acetone breath (fruity), polyuria, polydipsia and anorexia

Monitor weight at frequent intervals Use only insulin syringes which are

calibrated in units Before withdrawing the insulin, rotate the

vial between the palms of the hands to ensure the medication is mixed into the solution. Do not shake the vial.

When mixing two insulins, draw up the regular insulin first. This prevents contamination of the regular insulin.

Insulin should be kept in a cool place and does not need refrigeration. Opened vials should not be used after 30 days

Regular insulin is the only insulin that can be administered IV. The solution in the vial should be clear and not cloudy.

Regular insulin may be administered direct IV undiluted or diluted in commonly used IV solutions; however insulin potency may be reduced by plastic or glass administration systems

Regular insulin my be administered up to 50 units in over 1 minute.

Administer glucagon, epinephrine or IV glucose 10-50% if the client is unresponsive during hypoglycemia

Instruct on injection sites: abdomen, posterior arms, anterior thighs, hips), rotation of sites to prevent lipodystrophy

Rotation of sites should be 1.5 inches apart, should be systematic and the site should not be used again for a 2-3-week period

Instruct that blood glucose should rise approximately 5 minutes after the administration of glucagon, if there is no response in 20 min, seek emergency assistance