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Nursing Pharmacology

Pharmacology

- most simply defined as study of drug.


Fundamentals of Pharmacology

1. Pharmacokinetics

- study of drug’s changes as it enters and passes through the body.

a. absorption

b. distribution

c. biotransformation / Metabolism

d. excretion


2. Pharmacodynamics

- mechanism by which drugs produce changes in body tissue.

a. desired effect - intended action of drugs

b. adverse effect - harmful unintended reactions

c. side effects – consequence reactions

d. toxicity – the degree which something is poisonous

digoxin = 0.5 – 2.0 ng/mL

lithium = 0.5 – 1.5 mEq/L


Safety and Efficacy

Nursing Principles :

1. Always verify the Six Rights .

a. the right medications

b. the right client

c. the right dosage

d. the right form, route and technique

e. the right time

f. the right documentation

2. Chart drug administration only after its been given, never before.

3. Never leave the medication on cart or tray unattended.

4. Chart observed therapeutic and adverse effects accurately and fully.

5. Check history for allergies and potential drug interactions before administering a

newly ordered drug.

6. Inform the prescribing physician of any observed adverse effects; if cannot be

located, inform the nursing supervisor

7. Question drug orders that are unclear, that appear to contain errors, or that have

potential to harm.

8. Take the following actions if an error occurs :

a. immediately notify the nursing supervisor, the prescribing physician, and the

pharmacist.

b. assess the client’s condition and provide any necessary care.

9. For postpartum women, advice to take drugs after breastfeeding.

Routes and Nursing considerations:

1. Enteral – oral, sublingual, rectal, gastric tubes

- capsulated pill, sustained release and enteric coated should not be crushed.

2. Parenteral – IV, IM, SQ, ID, IT, IA, epidural.

- vastus lateralis (safest site for IM)

3. Topical – skin, inhalants, mucus membrane.

Eye medications :

- administer eyedrops first then ointment.

- use a separate bottle for each client.

- instruct the client to tilt the head backward, open eyes and look up.

- avoid contact of medication bottle to the eyeball.

- place prescribed dose in the lower conjunctival sac.

- instruct the client to press the inner canthus for 30-60 seconds.

- instruct the client to close the eye gently.


Ear drops

- in infant and children younger than 3 y.o, pull pinna downward and backward.

- in older children and adult, upward and backward.

- direct the solution on the wall of the ear canal, not directly on the ear drum.



CLASSIFICATIONS OF DRUGS

DRUGS AFFECTING THE CENTRAL AND AUTONOMIC SYSTEM


Cholinergic Agents (Parasympathomimetic)

Prototype :

- synthetic acetylcholine, pilocarpine, carbachol, bethanecol (Urocholine), edrophonium (Tensilon), neostigmine (Prostigmine), pyridostigmine (Mestinon).

Mechanism of action :

- stimulates cholinergic receptors by mimicking acetylcholine or inhibition of enzyme cholinesterase.

Indications :

- glaucoma, urine retention, Myasthenia Gravis

- antidote to neuromuscular blocking agents : tricyclic antidepressants and atropine

Adverse effects :

- blurring of vision, miosis

- increase in salivation, intestinal cramps

- bronchoconstriction, wheezing, DOB

- hypotension and bradycardia

Nursing considerations :

1. Warn & monitor clients of the side effects.

2. Have atropine available for use as antidote.

Cholinergic Blocking Agents (Parasympatholytic, Anticholinergics)

Prototype :

- atropine, scopolamine (Triptone), dicyclomine (Bentyl), propantheline (Pro-Banthine).

Mechanism of actions :

- block the binding of acetylcholine in the receptors of parasympathetic nerves.

Indications :

- use preoperatively to dry up secretions.

- treat spasticity of GI or urinary tract.

- use for treatment of bradycardia, asthma, parkinsonism.

- use for antidote in organophosphate poisoning.

Adverse effects :

- dry mouth , dilatation of pupils, tachycardia

- urinary retention, ileus, heat stroke

Nursing considerations :

1. Keep client’s in cool environment.

2. Watch out for signs of heatstroke and dehydration.

3. Encourage clients to increase fluid intake and use of sugarless gum/candy for dry

mouth.

4. For GI spasticity, administer 30 minutes before meals and at bed time.


Adrenergic Agents (Sympathomimetics)

Prototype :

- epinephrine, norepinephrine, ephedrine, dopamine, dobutamine, phenylephrine,

terbutaline, albuterol, isoproterenol.

Mechanism of actions :

- stimulate alpha and beta adrenergic receptor directly or trigger the release of

catecholamines indirectly causing sympathetic effects.

Indications :

- cardiopulmonary arrest, hypotension

- COPD and asthma, nasal congestions

- allergic reaction, anaphylactic shock

Adverse effects :

- restlessness, insomnia, tremors, nausea

- palpitations, angina, tachycardia, HPN

Nursing considerations :

1. Contraindicated in clients w/ hyperthyroidism,

pheochromocytoma & cardiovascular disease.

2. Monitor vital signs and advice precautions.

3. Should be taken with food.

Adrenergic Blocking Agents

Prototype :

a. Alpha blockers

- phentolamine (Regintine), phenoxybenzamine, prazosin (Minipress),reserpine (Serpasil), terazosin (Hytrin)

- clonidine (Catapress), methyldopa (Aldomet)

b. Beta blockers

- atenolol (Tenormin), esmolol (Brevibloc), metoprolol (Lopressor), nadolol (Corgard),

propanolol (Inderal), timolol ( Blocadren)

Mechanism of actions :

a. alpha blockers

- inhibits action of a-receptors in vascular smooth muscle to cause vasodilatation.

b. beta blockers

- compete with epinephrine in b-receptors in heart, pulmonary airways, peripheral

circulation and CNS.

Indications :

- Raynaud’s disease, hypertension, pheochromocytoma.

- angina, arrhythmias, mitral valve prolapse, glaucoma

Adverse effects :

- orthostatic hypotension, bradycardia, CHF

- depression, insomnia and vertigo

- bronchospasm and dyspnea, nasal stuffiness, cold extremities

Nursing considerations :

1. Administer oral alpha-blockers with milk to minimize GI side effects.

2. Administer oral beta-blockers before meals and at a.m. if insomnia occurs.

3. Check client’s apical pulse rate before drug administration, refer if below 60 bpm.

4. Hypotensive precautions.

5. Warn clients not to drive or operate dangerous machinery until he/she has

adjusted to medications.



SKELETAL MUSCLE RELAXANTS AGENTS

Prototype :

- methocarbamol (Robaxin), baclofen (Lioresal), dantrolene (Dantrium),

metaxalone (Skelaxin), orphanedrine (Norgesic), chlorzoxazone

Mechanism of actions:

- depress CNS

- inhibit calcium ion release in the muscle

- enhance the inhibitory action of GABA (gamma-amino butyric acid)

Indications :

- for acute musculoskeletal pain

- for muscle spasticity associated with multiple sclerosis, cerebral palsy, CVA, and

spinal cord injury.

Adverse effects :

- hypotonia, ataxia, hypotension, drowsiness

- blurred vision, bradycardia, depression, urine retention

Nursing considerations :

1. Caution clients that mental alertness may be impaired.

2. Monitor neuromuscular status, bowel and bladder functions.

3. Inform clients that maximum benefit of baclofen is attained for 1-2 months.

4. Reduce baclofen dosage gradually because of associated withdrawal symptoms :

Confusion, hallucinations, paranoia & rebound spasticity.



ANTICONVULSANTS

Prototype :

a. Hydantoins - phenytoin (Dilantin)

b. Barbiturates - phenobarbital ( Luminal)

c. Miscellaneous

- carbamazepine (Tegretol), diazepam, clorazepate (Tranxene),

valproic acid (Dapakene), ethosuximide (Zarontin).

Mechanism of action :

- treat seizures by depressing abnormal neuronal activity in motor cortex.

Adverse effects :

- sedation & drowsiness, gingival hyperplasia

- diplopia, nystagmus, vertigo, dizziness

- thrombocytopenia, aplastic anemia

Nursing considerations :

1. Advise female clients to use contraceptives.

2. Inform clients taking phenytoin that harmless urine discoloration is common.

3. Warn clients with diabetes that hydantoins may increase blood sugar level and that

valproic acid may produce a false positive result in urine ketone test.

4. Teach clients receiving carbamazepine to identify symptoms of bone marrow

depressions.

5. Reassure that barbiturates are not addictive at a low dosage.

6. Avoid taking alcohol with barbiturates.

7. Administer IV phenytoin slowly to avoid cardiotoxicity.

8. Avoid mixing other drugs in same syringe with phenytoin.



ANTIPARKINSONIAN AGENTS

Prototype :

a. Anticholinergic agents

- trihexyphenidyl (Artane), benztropine (Congentin)

b. Dopaminergic agents

- Levodopa, carbidopa-levodopa (Sinemet), amantadine (Symmetrel),

pergolide (Permax), selegiline (Eldepryl), bromocriptine.

Mechanism of actions :

a. anticholinergic agents

- inhibit cerebral motor centers.

b. dopaminergic agents

- increasing dopamine concentrations or

enhancing neurotransmitter functioning.

Adverse effects of dopaminergic agents:

a. levodopa – nausea, vomiting, anorexia, orthostatic hypotension,

dark-colored urine and sweat

b. amantidine – ankle edema, constipation

c. bromocriptine – palpitations, tachycardia

Nursing considerations :

1. Give dopaminergic agents after meals to reduce GI symptoms.

2. Reassure client that levodopa may cause harmless darkening of urine and sweat.

3. Avoid taking Vit B6 (pyridoxine) with levodopa because it speed up metabolism.

4. Educate clients to minimize orthostatic hypotension.

5. Elevate leg to reduce ankle edema.


CENTRAL NERVOUS SYSTEM STIMULANTS

Prototype :

- amphetamines, methylphenidate (Ritalin)

Mechanism of actions :

- increase excitatory CNS neurotransmitter activity and blocks inhibitory impulses.

Indications :

- for obesity (amphetamines)

- attention deficit hyperactivity disorders

- narcolepsy

- drug-induced respiratory depressions.

Adverse effects :

- nervousness, insomnia, restlessness

- hypertension, tachycardia, headache

- anorexia, dry mouth.

Nursing considerations :

1. Should be given at morning.

2. Don’t stop amphetamine abruptly to avoid withdrawal symptoms.

3. Monitor blood pressure and pulse.

4. Ice chips or sugarless gum for dry mouth.

5. Watch out for growth retardation in children taking methylphenidate.



DRUGS AFFECTING MENTAL FUNCTIONING


Sedatives, Hypnotics, and Anxiolytics

Prototype :

a. Benzodiazepines (For Alcohol withdraw )

- diazepam (Valium), lorazepam (Ativan),

alprazolam (Xanax), flurazepam (Dalmane)

b. Barbiturates

- amobarbital, phenobarbital, secobarbital

c. Miscellaneous

- chloral hydrate (Noctec), buspirone (Buspar), paraldehyde (Paral)

Mechanism of actions :

a. Benzodiazepines

- increase the effect of inhibitory neuro transmitter GABA

(gamma-amino butyric acid)

b. Barbiturates and Miscellaneous agents

- depress CNS

Indications :

- induce sleep, sedate and calm clients

Adverse effects :

- hangover-effect, dizziness, CNS depression

- respiratory depression, drug-dependence

Nursing considerations :

1. Warn clients of injuries and falls.

2. Brief period of confusion and excitement upon waking up is common with

benzodiazepines.

3. Warn clients not to discontinue medications abruptly without consulting a physician.

4. Avoid alcohol while taking these drugs.

6. Rotate and don’t shake the ampules of barbiturates. Don’t mix with other drugs.

7. Warn female clients that diazepam is associated with cleft lip.



ANTIDEPRESSANTS AND MOOD DISORDER DRUGS

Prototype :

a. Tricyclic antidepressants

- amitriptyline (Elavil), protriptyline (Vivactil),

- imipramine (Tofranil), desipramine

b. MAO (monoamine oxidase inhibitors )

- isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Pernate)

c. Second-generation antidepressants

- fluoxetine (Prozac), trazodone (Desyrel)

d. Lithium

Mechanism of actions :

a. Tricyclic antidepressants

- increase receptor sensitivity to serotonin and/or norepinephrine.

b. MAO inhibitors

- inhibit the enzyme MAO that metabolize the neurotransmitters norepinephrine and

serotonin.

c. Second – generation antidepressants

- inhibits the reuptake of serotonin.

d. Lithium

- increase serotonin & norepinephrine uptake

Adverse effects :

- dry mouth, blurred vision, urine retention, constipation (anticholinergic effects)

- orthostatic hypotension, insomnia

- hypertensive crisis (MAO)

- dehydration (Lithium).

Nursing considerations :

1. Caution client to rise slowly to reduce the effects of orthostatic hypotension.

2. Take antidepressant with food to enhance absorption

3. Explain to client that full response may take several weeks (2 weeks).

4. Assess client for constipation resulting from tricyclic antidepressant use.

5. Client taking MAO inhibitors should avoid tyramine-rich foods to avoid

hypertensive crisis.

- aged cheese, sour cream, yogurt, beer, wine, chocolate, soy sauce and yeast

- phentolamine (Regitine) is the drug of choice for hypertensive crisis.

6. Inform physician and withhold fluoxetine if client develop rashes.

7. Take lithium with food to reduce GI effects

- > 1.5 mEq/L blood level may cause toxicity manifested by:

confusion, lethargy, seizures, hyperreflexia.

- maintain salt and adequate fluid intake

- tremors may occur but it is temporary

- monitor white blood cell count (increase).



ANTIPSYCHOTIC DRUGS (NEUROLEPTICS)

Prototype :

a. Phenothiazines

- chlorpromazine (Thorazine),

- trifluoperazine (Stelazine),

- thioridazine (Mellaril)

b. Other Agents

- clozapine (Clozaril), haloperidol (Haldol)

Mechanism of action :

- block dopamine receptor in the limbic system, hypothalamus, and

other regions of the brain.

Adverse effects :

- Extra pyramidal symptoms such as dystonia, pseudoparkinsonism, and

an irreversible tardive dyskinesia as manifested by :

a. lip smacking

b. fine wormlike tongue movement

c. involuntary movements of arms and leg.

- Neuroleptic malignant syndrome

a. fever, tachycardia, tachypnea, diaphoresis, cardiovascular collapse

b. muscle rigidity, seizures.

- orthostatic hypotension

Nursing considerations :

1. Teach family members the signs of EPS and NMS, and report to physician

immediately.

2. Normalization of symptoms may not occur for several weeks after beginning of

therapy .

3. Avoid administering haloperidol intravenously

4. Watch out of neutropenia with clozapine.

5. Watch out for orthostatic hypotension and photosensitivity with phenothiazine.

6. Be sure that oral doses are swallowed, and not hoarded.



DRUGS USED IN PAIN MANAGEMENT

General Anesthetics

Prototype :

a. Inhalation anesthetics

- enflurane (Ethrane), halothane

- isoflurane (Forane), nitrous oxide

b. Injection anesthetics

- fentanyl (Sublimaze), ketamine (Ketalar),

thiopental Na (Penthotal), etomidate (Amidate)

Mechanism of actions :

- cause CNS depression, by producing loss of consciousness, unresponsiveness to pain

stimuli, and muscle relaxation.

Nursing considerations :

1. Instruct client NPO for 8 hours before administration.

2. Monitor cardio pulmonary depression and hypotension.

3. Monitor urinary retention.

4. Monitor body temperature

- malignant hyperthermic crisis : dantrolene (antidote)

5. Avoid alcohol or CNS depressants for 24 hours after anesthesia.

6. In patient who received halothane, monitor signs of hepatic fatal side effects :

- rash, fever, nausea, vomiting

- jaundice and altered liver function.



LOCAL AND TOPICAL ANESTHETIC

Prototype :

local: bupivacaine, lidocaine, tetracaine, procaine, mepivacaine, prilocaine

topical: benzocaine, butacaine, dibucaine, lignocaine

Mechanism of action :

- block transmission of impulses across nerve cell membrane.

Adverse effects :

- cardiac dysrhythmias

Nursing considerations :

- lignocaine + prilocaine (EMLA cream) should be applied topically 60 minutes before

procedure.

- administer cautiously to the areas of large broken skin.

- observe for fetal bradycardia in pregnant clients.



ANALGESICS

Prototype :

a. Narcotic analgesics

- codeine, meperidine (Demerol) morphine, butorphanol (Stadol)

nalbuphine (Nubain)

b. Non – narcotic analgesic

NSAIDs – aspirin (aminosalicylic acid), mefenamic acid (Ponstan),

ibuprofen (Motrin), naproxen, ketoprofen (Orudis), ketorolac.

paracetamol and acetaminophen (Tylenol)

Mechanism of actions :

a. Narcotic analgesics

- alter pain perception by binding to opioid receptors in CNS.

b. Non- narcotic analgesic

- relieves pain and fever by inhibiting the prostaglandin pathway.

Nursing considerations :

1. Monitor respiratory depression & hypotension in clients taking narcotic analgesic.

2. Injury and accident precautions in clients taking narcotic analgesic.

3. Warn clients about possibility of dependency, and do not discontinue narcotics

abruptly in the narcotic-dependent clients.

4. Naloxone is antidote for narcotic overdose.

5. Advice clients to take NSAIDs with food and monitor bleeding complications.

6. Aspirin is contraindicated in clients below 18 years old with flu-like symptoms.

7. Monitor hearing loss in clients taking aspirin.

8. Monitor liver function in clients taking acetaminophen.

9. N-acetylcysteine is antidote for paracetamol overdose.



DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM

ANTICOAGULANTS

Prototype :

- Heparin (SQ and IV)

- Warfarin (Orally)

Mechanism of actions :

a. Heparin

- prevents thrombin from converting fibrinogen to fibrin.

b. Warfarin

- suppress coagulation by acting as an

antagonist of vitamin K after 4-5 days.

Indications :

- thrombosis, pulmonary embolism, myocardial infarction

Adverse effect :

- bleeding

Nursing considerations :

1. HEPARIN sodium

- if given SQ don’t aspirate or rub the injection site (above the scapula - best site).

- therapeutic level 1.5-2.5 times normal PTT;

normal PTT is 20-35 sec. = 50-85 sec.

- antidote : (protamine sulfate)

2. WARFARIN sodium (coumadin)

- warfarin is used for long-term.

- onset of action is 4-5 days.

- therapeutic level is 1.5-2.5 times normal PT;

normal PT = 9.6 -11.8 sec. = 25 - 30 sec.

INR = 2 - 3

- should be taken at the same time of the day to maintain at therapeutic level.

- reduce intake of green leafy vegetables.

- antidote : Vitamin K (Aquamephyton)



THROMBOLYTICS

Prototype :

Streptokinase, Urokinase

Mechanism of actions :

- activates plasminogen to generates plasmin (enzyme that dissolve clots).

Indications :

- use early in the course of MI (within 4-6 hours of the onset)

Nursing considerations :

- monitor bleeding

- antidote: Aminocarpic acid


Antiplatelet Medications

Prototype: Aspirin, Dipyridamole (Persantin), Clopidoigrel (Plavix), Ticlopidine

Mechanism of action :

- inhibit the aggregation of platelet thereby prolonging bleeding time.

Indications :

- used in the prophylaxis of long-term complication following M.I, coronary

revascularization, and thrombotic CVA.

Nursing considerations :

- Monitor bleeding time ( NV = 1-9 mins)

- Take the medication with food.



CARDIAC GLYCOSIDES

Prototype:

- digoxin (Lanoxin) and digitoxin (Crystodigin)

Mechanism of actions :

- increase intracellular calcium, which causes the heart muscle fibers to contract more

efficiently, producing positive inotropic & negative chronotropic action.

Indications :

- use for CHF, atrial tachycardia and fibrillation

Nursing considerations:

- Monitor for toxicity as evidence by:

nausea, vomiting, anorexia, halo vision, confusion, bradycardia and heart blocks .

- Do not administer if pulse is less than 60 bpm.

- Should be caution in patient with hypothyroidism and hypokalemia.

- Antidote : Digi-bind

- Phenytoin is the drug of choice to manage digitalis-induced arrhythmia.


Nitrates

Prototype :

- isosorbide dinitrate (Isordil)

- nitroglycerine (Deponit, Nitrostat)

Mechanism of action :

- produce vasodilatation including coronary artery.

Indications :

- angina pectoris, MI, peripheral arterial occlusive disease.

Adverse effects:

- headache, orthostatic hypotension .

Nursing Considerations :

1. Transdermal patch

- apply the patch to a hairless area using a new patch and different site each day.

- remove the patch after 12-24 hours, allowing 10-12 hours “patch free” each day to

prevent tolerance.

2. Sublingual medications :

- note the BP before giving the medication.

- offer sips of water before giving because dryness may inhibit absorption.

- one tablet for pain and repeat every 5 mins. for a total of three doses; if not relieved

after 15 mins., seek medical help.

- stinging or burning sensation indicates that the tablet is fresh.

- instruct patient not to swallow the pill

- sustained release medications should be swallowed and not to be crush.

- protect the pills from light.



ANTI-ARRHYTHMIC DRUGS

Class I (block Na channels)

IA - quinidine, procainamide

IB - lidocaine

IC - flecainamide

Class II (Beta-blockers)

propanolol, esmolol

Class III (block K channels)

amiodarone, bretylium

Class IV (block Ca channels)

verapramil, diltiazem

Nursing considerations :

1. Watch out for signs of CHF.

2. Have client weigh themselves and report

weight gain.

3. Watch out for signs of lidocaine toxicity :

- confusion and restlessness



ANTILIPEMICS

Prototype :

a. cholesterol-lowering agents

- cholestyramine, colestipol, lovastatin

b. triglyceride-lowering agents

- gemfibrozil, clofibrate

Mechanism of actions :

- interfere with cholesterol synthesis as well as

decreasing lipoprotein & triglyceride synthesis.

Nursing considerations :

- monitor liver functions while using statins.

- prevent constipation, flatulence, cholelithiasis

- encourage increase fluid and fiber intake.



ANTI – HYPERTENSIVE

Angiotensin-Converting Enzyme (ACE) Inhibitors

Prototype :

captopril (Capoten), enalapril (Vasotec), quinapril, lisinopril

Mechanism of actions :

- prevent peripheral vasoconstriction by blocking conversion of angiotensin I to

angiotensin II decreasing peripheral resistance.

Adverse effect :

- it cause hyperkalemia