This document discusses various classes of antimicrobial agents including their mechanisms of action, therapeutic uses, and side effects. It covers sulfonamides, penicillins, cephalosporins, tetracyclines, aminoglycosides, and quinolones. For each class, it provides examples of specific drugs, how they work, what types of infections they treat, and potential adverse effects. The goal is to identify the infecting organism and select the appropriate antibiotic based on its susceptibility profile.
The most common mode of action for antibiotics is the inhibition of cell wall synthesis. Antibiotics that inhibit cell wall synthesis work because of the fact that most eubacteria have peptidoglycan-based cell walls but mammals do not. Growth is prevented by inhibiting peptidoglycan synthesis. Thus these antibiotics only work for actively growing bacteria. The cell wall of new bacteria that grew in the presence of cell-wall-synthesis inhibitors is deprived of peptidoglycan. These bacteria will be subjected to osmotic lysis.In addition, gram-negative bacteria generally are less susceptible to inhibitors of cell wall synthesis than are gram-positive bacteria. In the former cell wall synthesis inhibitors fail to reach the cell wall because they are blocked by the gram-negative outer membrane.Penicillin is the classic example of an inhibitor of cell wall synthesis. Other examples include: ampicillin, bacitracin, carbapenems, cephalosporin, methicillin, oxacillin and vancomycin
Tetracyclines slide contains full information about uses, adverse effect, marketed preparation, precaution, route of drug administration, antimicrobial spectrum, mechanism of action, pharmacokineticks and pharmacodynamics of tetracyclines. This slide is very helpful for pharmacy and pharmacology student for the study about tetracyclines.
Pharmacology of Penicllins (Beta lactam antibiotics), description of their mechanism of action, mechanism of resistance, classification, indications and adverse effects
The most common mode of action for antibiotics is the inhibition of cell wall synthesis. Antibiotics that inhibit cell wall synthesis work because of the fact that most eubacteria have peptidoglycan-based cell walls but mammals do not. Growth is prevented by inhibiting peptidoglycan synthesis. Thus these antibiotics only work for actively growing bacteria. The cell wall of new bacteria that grew in the presence of cell-wall-synthesis inhibitors is deprived of peptidoglycan. These bacteria will be subjected to osmotic lysis.In addition, gram-negative bacteria generally are less susceptible to inhibitors of cell wall synthesis than are gram-positive bacteria. In the former cell wall synthesis inhibitors fail to reach the cell wall because they are blocked by the gram-negative outer membrane.Penicillin is the classic example of an inhibitor of cell wall synthesis. Other examples include: ampicillin, bacitracin, carbapenems, cephalosporin, methicillin, oxacillin and vancomycin
Tetracyclines slide contains full information about uses, adverse effect, marketed preparation, precaution, route of drug administration, antimicrobial spectrum, mechanism of action, pharmacokineticks and pharmacodynamics of tetracyclines. This slide is very helpful for pharmacy and pharmacology student for the study about tetracyclines.
Pharmacology of Penicllins (Beta lactam antibiotics), description of their mechanism of action, mechanism of resistance, classification, indications and adverse effects
A Power point presentation on Betalactam antibiotics suitable for undergraduate medical students. This Ppt is already presented in theory class lectures to the students of NEIGRIHMS, Shillong, Meghalaya
Cephalosporins & other β lactam antibiotics & cell wall destructorsFarazaJaved
this ppt cover all 5 generations of cephalosporins and about beta lactam atibiotics and cell wall destructors data available till now. hope u ll find it useful.
Microbiology is the study of microorganisms.
The overall theme of the Microbiology course is to study the relationship between microbes and our lives.
Microorganisms (microbes) are organisms that are too small to be seen with the unaided eye, and usually require a microscope to be seen.
This relationship involves harmful effects such as diseases and food spoilage as well as many beneficial effects.
A Power point presentation on Betalactam antibiotics suitable for undergraduate medical students. This Ppt is already presented in theory class lectures to the students of NEIGRIHMS, Shillong, Meghalaya
Cephalosporins & other β lactam antibiotics & cell wall destructorsFarazaJaved
this ppt cover all 5 generations of cephalosporins and about beta lactam atibiotics and cell wall destructors data available till now. hope u ll find it useful.
Microbiology is the study of microorganisms.
The overall theme of the Microbiology course is to study the relationship between microbes and our lives.
Microorganisms (microbes) are organisms that are too small to be seen with the unaided eye, and usually require a microscope to be seen.
This relationship involves harmful effects such as diseases and food spoilage as well as many beneficial effects.
5. Antibiotics
– Medications used to treat bacterial infections
– Ideally, before beginning antibiotic therapy, the
suspected areas of infection should be cultured to
identify the causative organism and potential
antibiotic susceptibilities.
6. Antibiotics
– Empiric therapy: treatment of an infection before
specific culture information has been reported or
obtained
– Prophylactic therapy: treatment with antibiotics to
prevent an infection, as in intra-abdominal surgery
7. Antibiotics
– Bactericidal: kill bacteria
– Bacteriostatic: inhibit growth of susceptible
bacteria, rather than killing them immediately; will
eventually lead to bacterial death
8. Antibiotics: Sulfonamides
– One of the first groups of antibiotics
– sulfadiazine
– sulfamethizole
– sulfamethoxazole
– sulfisoxazole
9. Sulfonamides: Mechanism of Action
– Bacteriostatic action
– Prevent synthesis of folic acid required for
synthesis of purines and nucleic acid
– Does not affect human cells or certain bacteria—
they can use preformed folic acid
10. Sulfonamides: sulfamethoxazole
Therapeutic Uses
– Azo-Gantanol
– Combined with phenazopyridine (an analgesic-
anesthetic that affects the mucosa of the urinary
tract).
– Used to treat urinary tract infections (UTIs) and to
reduce the pain associated with UTIs .
– Bactrim
– Combined with trimethoprim.
– Used to treat UTIs, Pneumocystis carinii pneumonia,
ear infections, bronchitis, gonorrhea, etc.
11. Sulfonamides: sulfisoxazole
Therapeutic Uses
– Azo-Gantrisin
– Combined with phenazopyridine
– Used for UTIs
– Pediazole
– Combined with erythromycin
– Used to treat otitis media
12. Sulfonamides: Side Effects
– Body System Effect
– Blood Hemolytic and aplastic anemia,
thrombocytopenia
– Integumentary Photosensitivity, exfoliative
dermatitis, Stevens-Johnson syndrome, epidermal
necrolysis
13. • Sulfonamides: Side Effects
– Body System Effect
– GI Nausea, vomiting, diarrhea, pancreatitis
– Other Convulsions, crystalluria, toxic nephrosis,
headache, peripheral neuritis, urticaria
18. • Antibiotics: Penicillins
– First introduced in the 1940s
– Bactericidal: inhibit cell wall synthesis
– Kill a wide variety of bacteria
– Also called “beta-lactams”
19. • Antibiotics: Penicillins
– Bacteria produce enzymes capable of destroying
penicillins.
– These enzymes are known as beta-lactamases.
– As a result, the medication is not effective.
20. • Antibiotics: Penicillins
– Chemicals have been developed to inhibit these
enzymes:
• clavulanic acid
• tazobactam
• sulbactam
– These chemicals bind with beta-lactamase and
prevent the enzyme from breaking down the
penicillin
22. • Penicillins: Mechanism of Action
– Penicillins enter the bacteria via the cell wall.
– Inside the cell, they bind to penicillin-binding
protein.
– Once bound, normal cell wall synthesis is
disrupted.
– Result: bacteria cells die from cell lysis.
– Penicillins do not kill other cells in the body.
23. • Penicillins: Therapeutic Uses
– Prevention and treatment of infections caused by
susceptible bacteria, such as:
• gram-positive bacteria
• Streptococcus, Enterococcus, Staphylococcus species
24. • Penicillins: Adverse Effects
– Allergic reactions occur in 0.7% – 8% of
treatments
• urticaria, pruritus, angioedema
– 10% of allergic reactions are life-threatening
– and
– 10% of these are fatal
25. • Penicillins: Side Effects
– Common side effects:
• nausea, vomiting, diarrhea, abdominal pain
– Other side effects are less common
27. • Antibiotics: Cephalosporins
– Semisynthetic derivatives from a fungus
– Structurally and pharmacologically related to
penicillins
– Bactericidal action
– Broad spectrum
– Divided into groups according to their
antimicrobial activity
29. • Cephalosporins: First Generation
– cefazolin cephalexin
– (Ancef and Kefzol) (Keflex and Keftab)
– IV and PO PO
• used for surgical prophylaxis, URIs, otitis media
30. • Cephalosporins: Second Generation
– cefaclor • cefonicid
– cefprozil • ceforanide
– cefamandole • cefmetazole
– cefoxitin • cefotetan
– cefuroxime
• Good gram-positive coverage
• Better gram-negative coverage than first generation
31. • Cephalosporins: Second Generation
– Cefoxitin cefuroxime
– (Mefoxin) (Kefurox and Ceftin)
– IV and IM PO
– Used prophylactically for Surgical prophylaxis
abdominal or colorectal surgeries Does not kill
Also kills anaerobes anaerobes
32. • Cephalosporins: Third Generation
– cefixime • ceftizoxime
– cefpodoxime proxetil • ceftriaxone
– cefoperazone • ceftazidime
– cefotaxime • moxalactam
• Most potent group against gram-negative
• Less active against gram-positive
33. • Cephalosporins: Third Generation
– cefixime (Suprax)
– Only oral third-generation agent
– Best of available oral cephalosporins against gram-
negative
– Tablet and suspension
– ceftriaxone (Rocephin)
– IV and IM, long half-life, once-a-day dosing
– Easily passes meninges and diffused into CSF to treat
CNS infections
34. • Cephalosporins: Third Generation
– ceftazidime (Ceptaz, Fortaz, Tazidime, Tazicef)
– IV and IM
– Excellent gram-negative coverage
– Used for difficult-to-treat organisms such as
Pseudomonas spp.
– Eliminated renally instead of biliary route
– Excellent spectrum of coverage
35. • Cephalosporins: Fourth Generation
– cefepime (Maxipime)
– Newest cephalosporin agents.
– Broader spectrum of antibacterial activity than
third generation, especially against gram-positive
bacteria.
38. • Antibiotics: Tetracyclines
– Natural and semi-synthetic
– Obtained from cultures of Streptomyces
– Bacteriostatic—inhibit bacterial growth
– Inhibit protein synthesis
– Stop many essential functions of the bacteria
39. • Antibiotics: Tetracyclines
– Bind to Ca 2+ and Mg 2+ and Al 3+ ions to form
insoluble complexes
– Thus, dairy products, antacids, and iron salts
reduce absorption of tetracyclines
40. • Tetracyclines: Therapeutic Uses
– Wide spectrum:
• gram-negative, gram-positive, protozoa, Mycoplasma,
Rickettsia, Chlamydia, syphilis, Lyme disease
– Demeclocycline is also used to treat SIADH, and
pleural and pericardial effusions
41. • Tetracyclines: Side Effects
– Strong affinity for calcium
– Discoloration of permanent teeth and tooth
enamel in fetuses and children
– May retard fetal skeletal development if taken
during pregnancy
42. • Tetracyclines: Side Effects
– Alteration in intestinal flora may result in:
– Superinfection (overgrowth of nonsusceptible
organisms such as Candida)
– Diarrhea
– Pseudomembranous colitis
43. • Tetracyclines: Side Effects
– May also cause:
– Vaginal moniliasis
– Gastric upset
– Enterocolitis
– Maculopapular rash
46. • Aminoglycosides
– Natural and semi-synthetic
– Produced from Streptomyces
– Poor oral absorption; no PO forms
– Very potent antibiotics with serious toxicities
– Bactericidal
– Kill mostly gram-negative; some gram-positive
also
47. • Aminoglycosides
– Used to kill gram-negative bacteria such as
Pseudomonas spp., E. coli, Proteus spp., Klebsiella
spp., Serratia spp.
– Often used in combination with other antibiotics
for synergistic effect.
48. • Aminoglycosides
– Three most common (systemic): gentamicin,
tobramycin, amikacin
– Cause serious toxicities:
• Nephrotoxicity (renal failure)
• Ototoxicity (auditory impairment and vestibular [eighth
cranial nerve])
– Must monitor drug levels to prevent toxicities
49. • Aminoglycosides: Side Effects
– Ototoxicity and nephrotoxicity are the most significant
– Headache
– Paresthesia
– Neuromuscular blockade
– Dizziness
– Vertigo
– Skin rash
– Fever
– Superinfections
51. • Quinolones
– Excellent oral absorption
– Absorption reduced by antacids
– First oral antibiotics effective against gram-
negative bacteria
52. • Quinolones: Mechanism of Action
– Bactericidal
– Effective against gram-negative organisms and
some gram-positive organisms
– Alter DNA of bacteria, causing death
– Do not affect human DNA
57. • Macrolides: Therapeutic Uses
– Strep infections
– Streptococcus pyogenes (group A beta-hemolytic
streptococci)
– Mild to moderate URI
– Haemophilus influenzae
– Spirochetal infections
– Syphilis and Lyme disease
– Gonorrhea, Chlamydia, Mycoplasma
58. • Macrolides: Side Effects
– GI effects, primarily with erythromycin:
– nausea, vomiting, diarrhea, hepatotoxicity,
flatulence, jaundice, anorexia
– Newer agents, azithromycin and clarithromycin:
fewer side effects, longer duration of action,
better efficacy, better tissue penetration
59. • Antibiotics: Nursing Implications
– Before beginning therapy, assess drug allergies;
hepatic, liver, and cardiac function; and other lab
studies.
– Be sure to obtain thorough patient health history,
including immune status.
– Assess for conditions that may be
contraindications to antibiotic use, or that may
indicate cautious use.
– Assess for potential drug interactions.
60. • Antibiotics: Nursing Implications
– It is ESSENTIAL to obtain cultures from appropriate
sites BEFORE beginning antibiotic therapy.
61. • Antibiotics: Nursing Implications
– Patients should be instructed to take antibiotics
exactly as prescribed and for the length of time
prescribed; they should not stop taking the
medication early when they feel better.
– Assess for signs and symptoms of superinfection:
fever, perineal itching, cough, lethargy, or any
unusual discharge.
62. • Antibiotics: Nursing Implications
– For safety reasons, check the name of the
medication carefully since there are many agents
that sound alike or have similar spellings.
63. • Antibiotics: Nursing Implications
– Each class of antibiotics has specific side effects
and drug interactions that must be carefully
assessed and monitored.
– The most common side effects of antibiotics are
nausea, vomiting, and diarrhea.
– All oral antibiotics are absorbed better if taken
with at least 6 to 8 ounces of water.
64. • Antibiotics: Nursing Implications
– Sulfonamides
– Should be taken with at least 2400 mL of fluid per
day, unless contraindicated.
– Due to photosensitivity, avoid sunlight and
tanning beds.
– These agents reduce the effectiveness of oral
contraceptives.
65. • Antibiotics: Nursing Implications
– Penicillins
– Any patient taking a penicillin should be carefully
monitored for an allergic reaction for at least 30
minutes after its administration.
– The effectiveness of oral penicillins is decreased
when taken with caffeine, citrus fruit, cola
beverages, fruit juices, or tomato juice.
66. • Antibiotics: Nursing Implications
– Cephalosporins
– Orally administered forms should be given with
food to decrease GI upset, even though this will
delay absorption.
– Some of these agents may cause an Antabuse-like
reaction when taken with alcohol.
67. • Antibiotics: Nursing Implications
– Tetracyclines
– Milk products, iron preparations, antacids, and
other dairy products should be avoided because
of the chelation and drug-binding that occurs.
– All medications should be taken with 6 to 8
ounces of fluid, preferably water.
– Due to photosensitivity, avoid sunlight and
tanning beds.
68. • Antibiotics: Nursing Implications
– Aminoglycosides
– Monitor peak and trough blood levels of these
agents to prevent nephrotoxicity and ototoxicity.
– Symptoms of ototoxicity include dizziness,
tinnitus, and hearing loss.
– Symptoms of nephrotoxicity include urinary casts,
proteinuria, and increased BUN and serum
creatinine levels.
69. • Antibiotics: Nursing Implications
– Macrolides
– These agents are highly protein-bound and will
cause severe interactions with other protein-
bound drugs.
– The absorption of oral erythromycin is enhanced
when taken on an empty stomach, but because of
the high incidence of GI upset, many agents are
taken after a meal or snack.
70. • Antibiotics: Nursing Implications
– Monitor for therapeutic effects:
– Disappearance of fever, lethargy, drainage, and
redness
73. Viruses
• Obligate intracellular parasites
• Consist of a core genome in a protein shell
and some are surrounded by a lipoprotein
• lack a cell wall and cell membrane
• do not carry out metabolic processes
• Replication depends on the host cell
machinery
74. Anti Viral Agents
• Block viral entry into the cell or must work
inside the cell
• Most agents are pyrimidine or purine
nucleoside analogs
75.
76. Understanding Viruses
Viral Replication
• A virus cannot replicate on its own.
• It must attach to and enter a host cell.
• It then uses the host cell’s energy to synthesize protein, DNA,
and RNA.
77. Understanding Viruses
Viruses are difficult to kill because they live
inside our cells.
• Any drug that kills a virus may also kill our cells.
78. Viral Infections
Competent immune system:
• Best response to viral infections
• A well-functioning immune system will eliminate
or effectively destroy virus replication
Immunocompromised patients have frequent viral
infections
• Cancer patients, especially leukemia or lymphoma
• Transplant patients, due to pharmacological therapy
• AIDS patients, disease attacks immune system
79. Antivirals
Key characteristics of antiviral drugs:
• Able to enter the cells infected with virus.
• Interfere with viral nucleic acid synthesis and/or regulation.
• Some agents interfere with ability of virus
to bind to cells.
• Some agents stimulate the body’s immune system.
80. Antivirals
Viruses killed by current antiviral therapy:
• cytomegalovirus (CMV)
• herpes simplex virus (HSV)
• human immunodeficiency virus (HIV)
• influenza A (the “flu”)
• respiratory syncytial virus (RSV)
86. Clinical Uses
Zidovudine
• Available in IV and oral formulations
• activity against HIV-1, HIV-2, and human T cell
lymphotropic viruses
• mainly used for treatment of HIV, decreases
rate of progression and prolongs survival
• prevents mother to newborn transmission of
HIV
88. Tenofavir
• An acyclic nucleoside phosphonate analog of
adenosine
• M.O.A.- competively inhibits HIV reverse
transcriptase and causes chain termination
after incorporation into DNA
• Uses – in combination with other
antiretrovirals for HIV-1 suppression
89. Adefovir
• An analog of adenosine monophosphate
• Phosphorylated by cellular kinases
• M.O.A. - Competitively inhibits HBV DNA
polymerase and results in chain termination
after incorporation into viral DNA
• Uses - Hepatitis B
• Side effects - nephrotoxicity
91. Interferons
• Interferon Alfa
• Endogenous proteins
• induce host cell enzymes that inhibit viral RNA translation
and cause degradation of viral mRNA and tRNA
• Bind to membrane receptors on cell surface
• May also inhibit viral penetration, uncoating, mRNA
synthesis, and translation, and virion assembly and release
www.freelivedoctor.com
92. Interferons
• Pegylated interferon Alfa
• A linear or branced polyethylene gylcol (PEG)
moiety is attached to covalently to interferon
• Increased half-life and steady drug
concentrations
• Less frequent dosing
• Tx chronic hepatitis C in combination with
ribavirin
www.freelivedoctor.com
93. Ribavirin
• A guanosine analog
• phosphorylated intracellularly by host
enzymes
• inhibits capping of viral messenger RNA
• inhibits the viral RNA-dependent RNA
polymerase
• inhibits replication of DNA and RNA viruses
www.freelivedoctor.com
96. Amantadine and Rimantadine
– cyclic amines
– inhibit the uncoating of viral RNA therefore
inhibiting replication
– resistance due to mutations in the RNA
sequence coding for the structural M2
protein
– used in the prevention and treatment of
Influenza A
www.freelivedoctor.com
97. Zanamivir and Oseltamivir
• Inhibits the enzyme neuraminidase
• inhibit the replication of influenza A and
Influenza B
• treats uncomplicated influenza infections
• administered intranasally
www.freelivedoctor.com
98. Antivirals: Nursing Implications
• Before beginning therapy, thoroughly
assess underlying disease and medical history,
including allergies.
• Assess baseline VS and nutritional status.
• Assess for contraindications, conditions
that may indicate cautious use, and potential drug
interactions.
99. Antivirals: Nursing Implications
• Be sure to teach proper application technique for ointments,
aerosol
powders, etc.
• Emphasize hand washing before and after administration of
medications to prevent site contamination and spread of
infection.
• Patients should wear a glove or finger cot when applying
ointments or solutions to affected areas.
100. Antivirals: Nursing Implications
• Instruct patients to consult their physician before
taking any other medication, including OTC
medications.
• Emphasize the importance of good hygiene.
• Inform patients that antiviral agents are not cures,
but do help to manage symptoms.
101. Antivirals: Nursing Implications
• Instruct patients on the importance of taking these
medications exactly as prescribed and for the full course
of treatment.
• With zidovudine:
• Inform patients that hair loss MAY occur so that they are
prepared for this rare adverse reaction.
• This medication should be taken on an empty stomach.
103. Antivirals: Nursing Implications
Monitor for therapeutic effects:
• effects will vary depending on the type of viral infection
• Effects range from delayed progression of AIDS
and ARC to decrease in flu-like symptoms, decreased
frequency of herpes-like flare-ups,
or crusting over of herpetic lesions.
105. • Fungi
– Also known as mycoses
– Very large and diverse group of microorganisms
– Broken down into yeasts and molds
106. • Yeasts
– Single-cell fungi
– Reproduce by budding
– Very useful organisms
• Baking
• Alcoholic beverages
107. • Molds
– Multicellular
– Characterized by long, branching filaments called
hyphae
108. • Mycotic Infections
– Four General Types
– Cutaneous
– Subcutaneous
– Superficial
– Systemic*
• *Can be life-threatening
• *Usually occur in immunocompromised host
109. • Mycotic Infections
– Candida albicans
– Due to antibiotic therapy, antineoplastics, or
immunosuppressants
– May result in overgrowth and systemic infections
110. • Mycotic Infections
– In the mouth:
– Oral candidiasis or thrush
– Newborn infants and immunocompromised
patients
113. • Antifungal Agents
– Broken down into four major groups based on
their chemical structure
– Polyenes: amphotericin B and nystatin
– Flucytosine
– Imidazoles: ketoconazole, miconazole,
clotrimazole, fluconazole
– Griseofulvin
114. • Antifungal Agents: Mechanism of Action
– Polyenes: amphotericin B and nystatin
– Bind to sterols in cell membrane lining
– Allow K+ & Mg++ to leak out, altering fungal cell
metabolism
– Result: fungal cell death
115. • Antifungal Agents: Mechanism of Action
– flucytosine
– Also known as 5-fluorocytosine (antimetabolite)
– Taken up by fungal cells and interferes with DNA synthesis
– Result: fungal cell death
• Antifungal Agents: Mechanism of Action
– Imidazoles ketoconazole, miconazole, clotrimazole,
fluconazole
– Inhibit an enzyme, resulting in cell membrane leaking
– Lead to altered cell membrane
– Result: fungal cell death
119. • Antifungal Agents: Nursing Implications
– Before beginning therapy, assess for
hypersensitivity, possible contraindications, and
conditions that require cautious use.
– Obtain baseline VS, CBC, liver function studies,
and ECG.
– Assess for other medications used (prescribed and
OTC) in order to avoid drug interactions.
120. • Antifungal Agents: Nursing Implications
– Follow manufacturer’s directions carefully for
reconstitution and administration.
– Monitor VS of patients receiving IV infusions every
15 to 30 minutes.
– During IV infusions, monitor I & O and urinalysis
findings to identify adverse renal effects.
121. • Antifungal Agents: Nursing Implications
– amphotericin B
– To reduce the severity of the infusion-related
reactions, pretreatment with an antipyretic
(acetaminophen), antihistamines, and antiemetics
may be given.
– A test dose of 1 mg per 20 mL 5% dextrose in
water infused over 30 minutes should be given.
– Use IV infusion pumps and the most distal veins
possible.
122. • Antifungal Agents: Nursing Implications
– Tissue extravasation of fluconazole at the IV site
may lead to tissue necrosis—monitor IV site
carefully.
– Oral forms of griseofulvin should be given with
meals to decrease GI upset.
– Monitor carefully for side/adverse effects.
123. • Antifungal Agents: Nursing Implications
– Monitor for therapeutic effects:
– Easing of the symptoms of infection
– Improved energy levels
– Normal vital signs, including temperature
124. ANTIHELMINTHIC
• Antihelmintics
• Drugs used to treat parasitic worm infections:
helmintic infections
• Unlike protozoa, helminths are large and have
complex cellular structures
• Drug treatment is very specific
125. • Antihelmintics
• It is VERY IMPORTANT to identify the causative
worm
• Done by finding the parasite ova or larvae in
feces, urine, blood, sputum, or tissue
– cestodes (tapeworms)
– nematodes (roundworms)
– trematodes (flukes)
126. • Antihelmintics: Mechanism of Action and Uses
• diethylcarbamazine (Hetrazan)
• Inhibits rate of embryogenesis
• thiabendazole (Mintezol)
• Inhibits the helminth-specific enzyme,
fumarate reductase
– Both used for nematodes (tissue and some
roundworms)
127. • Antihelmintics: Mechanism of Action
• piperazine (Vermizine) and pyrantel
(Antiminth)
• Blocks acetylcholine at the neuromuscular
junction, resulting in paralysis of the worms,
which are then expelled through the GI tract
– Used to treat nematodes (giant worm and
pinworm)
128. • Antihelmintics: Mechanism of Action
• mebendazole (Vermox)
• Inhibits uptake of glucose and other nutrients,
leading to autolysis and death of the parasitic
worm
– Used to treat cestodes and nematodes
129. • Antihelmintics: Mechanism of Action
• niclosamide (Niclocide)
• Causes the worm to become dislodged from
the GI wall
• They are then digested in the intestines and
expelled
– Used to treat cestodes
130. • Antihelmintics: Mechanism of Action
• oxamniquine (Vansil) and praziquantel (Biltricide)
• Cause paralysis of worms’ musculature and
immobilization of their suckers
• Cause worms to dislodge from mesenteric veins
to the liver, then killed by host tissue reactions
– Used to treat trematodes, cestodes (praziquantel
only)
132. ANTIPROTOZOALs
• Protozoal Infections
• Parasitic protozoa: live in or on humans
• malaria
• leishmaniasis
• amebiasis
• giardiasis
• trichomoniasis
133. Malaria
• Caused by the plasmodium protozoa.
• Four different plasmodium species.
• Cause: the bite of an infected adult mosquito.
• Can also be transmitted by infected individuals
via blood transfusion, congenitally, or via
infected needles by drug abusers.
134. Malarial Parasite (plasmodium)
• Two Interdependent Life Cycles
• Sexual cycle: in the mosquito
• Asexual cycle: in the human
– Knowledge of the life cycles is essential in
understanding antimalarial drug treatment.
– Drugs are only effective during the asexual cycle.
135. Plasmodium Life Cycle
• Asexual cycle: two phases
• Exoerythrocytic phase: occurs “outside” the
erythrocyte
• Erythrocytic phase: occurs “inside” the
erythrocyte
– Erythrocytes = RBCs
136. Antimalarial Agents
• Attack the parasite during the asexual phase,
when it is vulnerable
• Erythrocytic phase drugs: chloroquine,
hydroxychloroquine, quinine, mefloquine
• Exoerythrocytic phase drug: primaquine
• May be used together for synergistic or
additive killing power.
137. Antimalarials: Mechanism of Action
• 4-aminoquinoline derivatives chloroquine and
hydroxychloroquine
• Bind to parasite nucleoproteins and interfere
with protein synthesis.
• Prevent vital parasite-sustaining substances
from being formed.
• Alter pH within the parasite.
• Interfere with parasite’s ability to metabolize
and use erythrocyte hemoglobin.
• Effective only during the erythrocytic phase
138. Antimalarials: Mechanism of Action
• 4-aminoquinoline derivatives quinine and
mefloquine
• Alter pH within the parasite.
• Interfere with parasite’s ability to metabolize
and use erythrocyte hemoglobin.
• Effective only during the erythrocytic phase.
139. Antimalarials: Mechanism of Action
• diaminophyrimidines pyrimethamine and
trimethoprim
• Inhibit dihydrofolate reductase in the parasite.
• This enzyme is needed by the parasite to make
essential substances.
• Also blocks the synthesis of tetrahydrofolate.
• These agents may be used with sulfadoxine or
dapsone for synergistic effects.
140. Antimalarials: Mechanism of Action
• primaquine
• Only exoerythrocytic drug.
• Binds and alters DNA.
• sulfonamides, tetracyclines, clindamycin
• Used in combination with antimalarials to
increase protozoacidal effects
141. Antimalarials: Drug Effects
• Kill parasitic organisms.
• Chloroquine and hydroxychloroquine also
have antiinflammatory effects.
142. Antimalarials: Therapeutic Uses
• Used to kill plasmodium organisms, the
parasites that cause malaria.
• The drugs have varying effectiveness on the
different malaria organisms.
• Some agents are used for prophylaxis against
malaria.
• Chloroquine is also used for rheumatoid
arthritis and lupus.
143. Antimalarials: Side Effects
• Many side effects for the various agents
• Primarily gastrointestinal: nausea, vomiting,
diarrhea, anorexia, and abdominal pain
146. Protozoal Infections
• Transmission
• Person-to-person
• Ingestion of contaminated water or food
• Direct contact with the parasite
• Insect bite (mosquito or tick)
147. Antiprotozoals: Mechanism of Action
and Uses
• atovaquone (Mepron)
• Protozoal energy comes from the
mitochondria
• Atovaquone: selective inhibition of
mitochondrial electron transport
• Result: no energy, leading to cellular death
– Used to treat mild to moderate P. carinii
148. Antiprotozoals: Mechanism of Action
and Uses
metronidazole
• Disruption of DNA synthesis as well as nucleic
acid synthesis
• Bactericidal, amebicidal, trichomonacidal
– Used for treatment of trichomoniasis, amebiasis,
giardiasis, anaerobic infections, and antibiotic-
associated pseudomembranous colitis
149. Antiprotozoals: Mechanism of Action
and Uses
pentamidine
• Inhibits DNA and RNA
• Binds to and aggregates ribosomes
• Directly lethal to Pneumocystis carinii
• Inhibits glucose metabolism, protein and RNA
synthesis, and intracellular amino acid
transport
– Mainly used to treat P. carinii pneumonia and
other protozoal infections
150. Antiprotozoals: Mechanism of Action
and Uses
iodoquinol (Yodoxin, Di-Quinol)
• “ Luminal” or “contact” amebicide
• Acts primarily in the intestinal lumen of the
infected host
• Directly kills the protozoa
– Used to treat intestinal amebiasis
151. Antiprotozoals: Mechanism of Action
and Uses
paromomycin
• “Luminal” or “contact” amebicide
• Kills by inhibiting protein synthesis
– Used to treat amebiasis and intestinal protozoal
infections, and also adjunct therapy in
management of hepatic coma
154. • Antimalarial, Antiprotozoal, Antihelmintic
Agents: Nursing Implications
• Before beginning therapy, perform a thorough
health history and medication history, and
assess for allergies.
• Check baseline VS.
• Check for conditions that may contraindicate
use, and for potential drug interactions.
155. • Antimalarial, Antiprotozoal, Antihelmintic Agents:
Nursing Implications
• Some agents may cause the urine to have an
asparagus-like odor, or cause an unusual skin
odor, or a metallic taste; be sure to warn the
patient ahead of time.
• Administer ALL agents as ordered and for the
prescribed length of time.
• Most agents should be taken with food to reduce
GI upset.
156. • Antimalarial Agents: Nursing Implications
• Assess for presence of malarial symptoms.
• When used for prophylaxis, these agents
should be started 2 weeks before potential
exposure to malaria, and for 8 weeks after
leaving the area.
• Medications are taken weekly, with 8 ounces
of water.
157. • Antimalarial Agents: Nursing Implications
• Instruct patient to notify physician
immediately if ringing in the ears, hearing
decrease, visual difficulties, nausea, vomiting,
profuse diarrhea, or abdominal pain occur.
• Alert patients to the possible recurrence of
the symptoms of malaria so that they will
know to seek immediate treatment.
158. • Antimalarial, Antiprotozoal, Antihelmintic
Agents: Nursing Implications
• Monitor for side effects:
• Ensure that patients know the side effects that
should be reported.
• Monitor for therapeutic effects and adverse
effects with long-term therapy.