Pharmacology and Nutrition

LEARNING OUTCOMES

After studying this chapter, the student will be able to:

1. Differentiate between a bactericidal and bacteriostatic antimicrobial agent and describe when the use of each would be appropriate

2. Differentiate between narrow and broad-spectrum antimicrobial agents and explain when each would be appropriate to use

3. Explain the common drug in use for muscle relaxant

4. Identify the appropriate nursing actions in the administration of each class of antimicrobial agents ans muscle relaxant

 

ANTIMICROBIAL AGENT

SUSCEPTIBILITY OF THE BODY TO INFECTION

To understand the role of antimicrobial agents in treating infections, it is important to understand those factors that may increase the susceptibility of the body to infection: age, exposure to pathogenic organisms, disruption of the body’s normal barriers to infection, inadequate immunological defenses, impaired circulation, and poor nutritional status

CLASSIFICATION OF ANTIMICROBIAL AGENTS

Several different systems are used to classify antimicrobial agents. The following discussion

briefly describes each of these systems.

Bactericidal—Bacteriostatic

Bactericidal agents are those which have a killing action on the microbial agent. Bacteriostatic agents simply inhibit the growth of bacteria, thereby permitting the host’s immunological defenses to complete the job of destroying the organism. Bactericidal agents include the penicillin’s, cephalosporins, polymyxin, and vancomycin.

The bacteriostatic category includes the tetracyclines, sulfonamides, erythromycin, and

lincomycin. Some antimicrobial agents may exert either a bactericidal or a bacteriostatic action, depending on the dose used, the causative organsm being acted upon, and/or the site of action of the drug. The use of bactericidal agents is generally preferred in the treatment of serious, life-threatening infections and/or when the host’s immunological system is not functioning properly. For the treatment of minor infections in otherwise healthy individuals, there is little difference in the overall effectiveness of bactericidal or bacteriostatic agents.

Site of Action

Antimicrobial agents may also be classified on the basis of the site at which they exert their therapeutic actions in the bacterial organism:

agents that inhibit cell wall synthesis—Some antibiotics interfere with the synthesis of the

bacterial cell wall. This results in a loss of structural integrity of the bacterial cell and

the death of the organism. Such agents are generally bactericidal in their action.

agents that inhibit protein synthesis—Some agents exert their antimicrobial effect by

interfering with protein formation in the bacterial cell. Although such an action rarely leads

to the immediate death of the organism, it does prevent normal growth and reproduction and makes it easier for host defense mechanisms to finish the job of eradicating the organism. Drugs that exert such an action are, therefore, classified as bacteriostatic agents.

agents that interfere with the permeability of the bacterial cell membrane—These drugs

increase the permeability of the bacterial cell membrane, permitting leakage of intracellular

components. As this results in the immediate death of the organism, such antimicrobial

agents are usually considered to be bactericidal in their action.

antimetabolites—Drugs with antimetabolite action generally block or alter a specific metabolic step essential for the normal function and/or growth of the bacterial cell (e.g., the

synthesis of a specific essential nutrient). This action may result in either a bactericidal or a

bacteriostatic effect, depending on the nature of the metabolic action and the concentration

of drug achieved in the environment of the organism.

Narrow Spectrum—Extended or Broad Spectrum

Antimicrobial agents are often classified as having a narrow spectrum or an extended or broad spectrum of action. Those with a narrow spectrum are useful in treating infections caused by a relatively limited number of organisms (e.g., only gram-positive organisms). Extended or broad-spectrum agents act on a wide variety of different organisms. The use of narrow-spectrum agents may be desirable when the identity of the infecting organism—as well as its susceptibility to the action of the antibiotic—has been established.

Because of their limited action, such drugs are not likely to indiscriminately disrupt the normal bacterial flora of the body. They may, therefore, be somewhat safer to use than broader spectrum drugs that might disrupt both pathogenic and useful microorganisms found in the body.

Broad or extended spectrum antimicrobial agents are useful in treating infections in which the identity and susceptibility to antimicrobial treatment of the infecting organism(s) has not been established. Because of the wide range organisms that may be susceptible to a specific broad-spectrum antibiotic, there is an excellent likelihood that the drug will be effective in treating a specific infection.

ANTIBACTERIAL AGENTS

Antibacterial agents either destroy or inhibit the growth of both pathogenic and nonpathogenic bacteria. In other words, they exert a bactericidal or bacteriostatic effect. Major antibacterial agents include the penicillins, macrolides, cephalosporins, fluoroquinolones, tetracyclines, and aminoglycosides

 

KEY NURSING IMPLICATIONS

penicillin’s Differ in Their:

1. chemical stability in stomach acid

2. susceptibility to penicillinase (beta lactamase) destruction

3. spectrum of action, i.e., narrow or extended

4. route of administration

5. duration of action

6. site of action

 

Penicillin

ü  Monitor all clients receiving penicillin for signs of hypersensitivity, i.e., urticaria, laryngeal edema, skin rash, and anaphylactic shock. Discontinue therapy at the first sign of serious hypersensitivity reaction.

ü  Observe clients receiving penicillin in an emergency room or physician’s office for 30 minutes before allowing them to leave.

ü  Ticarcillin, mezlocillin, or piperacillin may cause bleeding abnormalities. Closely monitor clients with renal impairment.

ü  Administration with bacteriostatic antibiotics, e.g., erythromycin or tetracycline, may diminish effectiveness.

ü  Probenecid (Benemid) blocks renal tubular secretion of penicillins, and may cause higher blood levels and longer duration of action for penicillins.

ü  High intravenous doses of sodium or potassium salts of penicillins may produce electrolyte disturbances.

ü  Although not always essential, it is advisable to administer oral penicillin on an empty stomach with a full glass of water.

ü  To prevent peripheral IV site irritation, avoid infusing medication rapidly

ü   

Clients Receiving Penicillins

1. Take a careful medication history before administering penicillins.

2. Observe the client for indications of allergic reaction, including rash, fever, chills, and anaphylaxis.

3. Oral penicillins should be given 1–2 hours before or 2–3 hours after meals.

4. Injection sites must be checked carefully for signs of local reactions (e.g., redness,

phlebitis). Do not use the same needle for withdrawing the solution from the vial and administering it.

5. Never give procaine penicillin intravenously.

 

Cephalosporins

·         Monitor clients for signs of hypersensitivity, i.e., urticaria, laryngeal edema, skin rash, and anaphylactic shock.

·         Discontinue therapy at first sign of serious hypersensitivity reaction.

·         Use with caution in clients with renal impairment.

·         Make IM injections deep into musculature to reduce inflammatory reactions.

·         IV administration for prolonged periods or in high doses may cause thrombophlebitis. Use small gauge IV needles, large veins, and alternate infusion sites to reduce risk of such problems.

·         Bacteriostatic antimicrobial agents (e.g., erythromycins or tetracyclines) may interfere with cephalosporins' bactericidal action.

·         Probenecid administered with cephalosporins may increase and prolong their plasma levels by interfering with their renal tubular secretion.

·         Use of potentially nephrotoxic drugs, such as aminoglycosides or loop diuretics, with cephalosporins may increase likelihood of renal toxicity.

·         Use may result in a false positive reaction for glucose with Benedict's solution or Clinitest tablets. Glucose tests based on enzymatic reaction (e.g., Clinistix or Tes-Tape) are not affected by cephalosporin use.

·         Monitor clients for gastrointestinal distress, renal impairment and hematological changes. In clients with renal impairment, consult product information and adjust cephalosporin dose accordingly.

Clients Receiving Cephalosporins

1. Clients who are allergic to penicillin may also be allergic to cephalosporins.

2. Administer intramuscular injections into a large muscle mass to decrease pain.

3. Observe intravenous sites carefully for phlebitis

 

Tetracyclines

·         Avoid use in children under 8 because of possible interference with development of teeth and bones and staining of teeth.

·         Clients must avoid unprotected exposure to direct sunlight or UV light to reduce risk of phototoxicity.

·         IV therapy in excess of 2 g/day of drug may produce hepatotoxicity.

·         Should not be used during pregnancy.

·         Monitor clients for bacterial or fungal superinfection, particularly involving the GI tract and/or vagina.

·         Avoid use with calcium supplements, antacids, iron, or dairy products as these may reduce tetracycline absorption

Clients Receiving Tetracyclines

1. Avoid administering tetracycline simultaneously with sodium bicarbonate, iron

preparations, dairy products, and drugs containing zinc, aluminum, calcium, or

magnesium.

2. Avoid administration of tetracycline on an empty stomach.

3. Clients should avoid excess exposure to the sun or use a sunscreen if taking

demeclocycline.

4. Superinfections may develop. Good oral care is essential. Women prone to the

development of vaginal infections should advise the physician about this before

beginning therapy.

5. Because of effects on teeth and bone, tetracyclines are generally avoided in children under 8 years and in women during the last two trimesters of pregnancy.

6. Never administer a tetracycline preparation containing procaine intravenously.

 

Macrolides/Erythromycins

·         Monitor clients for signs of hepatotoxicity, i.e., malaise, nausea, vomiting, abdominal cramping, fever, jaundice, and/or abnormal hepatic function tests.

·         Hypersensitivity reactions may occur in some clients, ranging from mild skin rashes to anaphylaxis.

·         Oral doses should be taken 1 hour before or 2 hours after meals. Administer with food if GI upset occurs

Aminoglycosides

·         Monitor clients for signs of nephrotoxicity.

·         Neuromuscular blockade and respiratory paralysis may occur when administered with or shortly after anesthetics or muscle relaxants.

·         Provide good hydration to reduce likelihood of nephrotoxicity or neurotoxicity.

·         Avoid use of other drugs that produce ototoxicity, nephrotoxicity, or neurotoxicity.

·         To prevent peripheral IV site irritation, avoid infusing medication rapidly.

 

 

Clients Receiving Aminoglycosides

1. Obtain an accurate body weight before therapy is begun.

2. Observe the patient for nephrotoxicity and eighth cranial nerve damage (hearing and balance problems).

3. When aminoglycosides are used for treating urinary tract infections, avoid urine acidifiers such as cranberry, plum, and prune juices, as well as vitamin C.

4. Monitor peak and trough levels.

 

Other Antibacterial Agents

ü  Report evidence of allergic reaction, such as rash or itching.

ü  Report symptomatic improvement.

ü  Review administration and storage instructions that accompany product.

ü  To prevent peripheral IV site irritation, avoid infusing medication rapidly. Monitor site

 

Sulfonamide Products for Systemic Use

ü  Administer drugs on an empty stomach.

ü  Monitor for development of hypersensitivity reactions, particularly in clients with severe allergies or bronchial asthma. Skin rash is a common indication of hypersensitivity.

ü  Maintain adequate fluid intake to prevent crystalluria and stone formation.

ü  Monitor for development of hematological changes, such as a drop in white blood cell count.

ü  Protect client from direct sunlight or UV light to avoid phototoxic reaction.

ü  Initial therapy with these products may require somewhat higher doses than those listed below.

ü  Report symptomatic improvement

 

Antitubercular Drugs

ü  Determine prior use of these medications and therapeutic response.

ü  Note color and nature of sputum.

ü  Teach client appropriate hygiene to ensure safety of others.

ü  Stress the importance of completing the course of treatment

 

 

Antiviral Drugs

ü  Many viruses cannot be treated with antivirals because, by the time symptoms arise, the viruses have already replicated and most antiviral action is during replication.

ü  Used for a variety of viral infections from influenzae A, herpes simplex, RSV, AIDS-related Kaposi sarcoma, pneumocystis’ carinii pneumonia associated with AIDS, HIV infections

 

Clients Receiving Antiviral Agents

1. Amantadine HCl should be taken after meals. Clients are observed for orthostatic

hypotension, depression, gastrointestinal distress, and urinary retention.

2. Clients receiving vidarabine should have intake and output monitored and be

weighed daily.

3. A filter is used for vidarabine infusions.

4. Acyclovir is always administered intravenously as an infusion. Watch for nephrotoxicity, phlebitis, nausea, and vomiting, plus the development of hypersensitivity reactions.

Clients Taking Antimicrobial Drugs Should:

1. Know the drug’s name, dosage, administration schedule, and why the medication

is being taken.

2. Know any special instructions related to storage (e.g., refrigerate medication) and

administration (e.g., do not take with milk or milk products).

3. Be told the major adverse effects and what to do if these should occur.

4. Be advised never to use an expired medication.

5. Be encouraged to complete the course of treatment as prescribed.

6. Be instructed not to give their medication to someone else, as it may result in an

adverse reaction.

7. Avoid taking any antimicrobial drug that has not been prescribed for a particular

course of illness.

8. Report failure of the medication to successfully treat the infection.

9. Be encouraged to keep all follow-up appointments

 

Clients Receiving Antifungal Agents

1. Never reconstitute amphotericin with saline or water containing a bacteriostatic agent. Use only sterile water for injection, USP, with a bacteriostatic agent.

2. Intravenous solutions of amphotericin should be added to infusions of dextrose and water only.

3. Never use a solution of amphotericin which contains a precipitate. Use a prepared amphotericin solution within 24 hours or refrigerate it and protect it from light.

4. Monitor the vital signs and intake and output of all clients receiving amphotericin and miconazole infusions. Observe the client for fever, nausea, chills and headaches and for hypokalemia if the client is receiving amphotericin.

5. Observe the intravenous injection site for indications of phlebitis

 

NEUROMUSCULAR BLOCKING AGENTS

Sometimes it is clinically desirable to relax or inactivate one or more skeletal muscles to:

facilitate surgery by reducing muscle movement and/or to permit use of lower anesthetic

doses facilitate electroconvulsive therapy (ECT) by reducing excessive muscular contraction

prevent muscle spasm of the larynx (laryngospasm) in clients who require endotracheal

intubation aid in the treatment of tetanus (a disease characterized by severe muscle spasm)

Neuromuscular Blocking Agents (Intravenous)

§  Low serum potassium levels antagonize the action of these drugs, with acidosis potentiating their effects.

§  Antidotes (for competitive blocking agents) and emergency equipment to support respiration must be available when these drugs are given.

§  Monitor vital signs frequently after administration.

§  Evaluate the therapeutic effectiveness of these agents.

Neuromuscular Blocking Agents

1. Obtain a history of current drug use and drug allergies before neuromuscular

blocking agents are used.

2. Antidotes such as the anticholinesterase muscle stimulants and emergency equipment must always be available when these drugs are used.

3. Monitor vital signs carefully

Skeletal Muscle Stimulants

1. Assess the client’s ability to swallow, ptosis of the eyelids, and muscle strength

as well as vital signs.

2. Contact the physician whenever the client develops a weakened condition

that may be related to myasthenic crisis or cholinergic crisis.

3. Clients with myasthenia gravis should receive their medication early in the

morning before they eat or engage in self-care activities.

4. Physical activities are planned for the time shortly after taking medication

when the muscle strength is greatest.

5. Clients with myasthenia gravis are instructed to carry information about

their medication and must understand the importance of complying with the

medication schedule

CLIENT TEACHING

1. The nurse stresses safety measures for clients taking skeletal muscle relaxants that depress the (CNS). These measures include avoiding concomitant use of other drugs that depress the CNS, including ethanol, and avoidance of hazardous tasks, such as driving.

2. Clients taking skeletal muscle stimulants to treat myasthenia gravis need to be

informed concerning signs and symptoms of cholinergic crisis, so they can report these

to their physician and seek immediate medical care.

3. Clients with myasthenia gravis should be instructed to wear identification indicating

that they have the condition.

4. Clients with myasthenia gravis should be instructed to take their medication early in the

morning before breakfast and the importance of adhering to a strict schedule of medication

self-administration.

5. Clients with myasthenia gravis should be informed not to take any prescription or overthe-counter medication without consulting their physician.

Anti-Parkinson Drugs

1. Clients taking levodopa should be monitored for orthostatic hypotension and cardiac arrhythmias. Also watch for psychiatric disturbances.

2. Record the client’s positive responses to treatment as well as side effects experienced.

3. Clients taking amantadine are observed for psychological changes, orthostatic

hypotension, urinary retention, and gastrointestinal symptoms.

4. Anticholinergics may produce dry mouth, urinary retention, and constipation and may precipitate an acute attack of glaucoma. Monitor clients carefully.

5. Do not rush the client during administration of oral medications.

6. Clients taking levodopa should avoid foods and medications containing substantial amounts of pyridoxine (vitamin B6).

Self check

1. Explain common drud use for antibiotics and muscle relaxant
2. Explain nursing consideration when administering these two categories of drugs