Anti infective agents

1. Anti infective agents Chapters 37,38,39 & 41

2. Antibiotics: Definition 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

3. Antibiotics: Classes Sulfonamides Penicillins Cephalosporins Tetracyclines Macrolides Aminoglycosides Quinolones

7. Antibiotic Therapy 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 intraabdominal surgery

8. Antibiotic Therapy (cont’d) Therapeutic response Decrease in specific signs and symptoms of infection are noted (fever, elevated WBC, redness, inflammation, drainage, pain) Subtherapeutic response Signs and symptoms of infection do not improve

9. Antibiotic Therapy (cont’d) Four common mechanisms of action Interference with cell wall synthesis Interference with protein synthesis Interference with DNA replication Acting as a metabolite to disrupt critical metabolic reactions inside the bacterial cell

10. Actions of Antibiotics Bactericidal: kill bacteria Bacteriostatic: inhibit growth of susceptible bacteria, rather than killing them immediately; will eventually lead to bacterial death

11. Antibiotics: Sulfonamides One of the first groups of antibiotics sulfadiazine Sulfamethoxazole (Bactrim) sulfisoxazole

12. Sulfonamides: Mechanism of Action Bacteriostatic action Prevent synthesis of folic acid required for synthesis of purines and nucleic acid Do not affect human cells or certain bacteria—they can use preformed folic acid

13. Sulfonamides: Indications Treatment of UTIs caused by susceptible strains of: Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus mirabilis, Proteus vulgaris, Staphylococcus aureus Nocardiosis Pneumocystis carinii pneumonia (PCP) Upper respiratory tract infections Other uses

14. Sulfonamides:Combination Products trimethoprim/sulfamethoxazole Used to treat UTIs, PCP, otitis media, other conditions erythromycin/sulfisoxazole Used to treat otitis media sulfisoxazole Used to treat otitis media, UTIs, other conditions

15. Beta-Lactam Antibiotics Penicillins Cephalosporins Carbapenems Monobactams

16. Penicillins Natural penicillins Penicillinase-resistant penicillins Aminopenicillins Extended-spectrum penicillins

17. Penicillins (cont’d) Natural penicillins penicillin G, penicillin V potassium Penicillinase-resistant penicillins Cloxacillin Aminopenicillins amoxicillin, ampicillin, pivamicillin Anti-pseudomonal penicillins piperacillin sodium

18. Penicillins (cont’d) First introduced in the 1940s Bactericidal: inhibit cell wall synthesis Kill a wide variety of bacteria Also called “beta-lactams”

19. Penicillins (cont’d) Bacteria produce enzymes capable of destroying penicillins These enzymes are known as beta-lactamases As a result, the medication is not effective

20. Penicillins (cont’d) Chemicals have been developed to inhibit these enzymes: Clavulanic acid (Clavulin) Tazobactam Sulbactam These chemicals bind with beta-lactamase and prevent the enzyme from breaking down the penicillin

21. 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

22. Penicillins: Indications Prevention and treatment of infections caused by susceptible bacteria, such as: Gram-positive bacteria Streptococcus, Enterococcus, Staphylococcus spp.

23. Penicillins: Adverse Effects Allergic reactions occur in 0.7% to 8% of cases Urticaria, pruritus, angioedema 10% of allergic reactions are life threatening 10% of these are fatal

24. Penicillins: Side Effects Common side effects Nausea, vomiting, diarrhea, abdominal pain Other side effects are less common

25. Cephalosporins First generation Second generation Third generation Fourth generation

26. Cephalosporins (cont’d) Semisynthetic derivatives from a fungus Structurally and pharmacologically related to penicillins Bactericidal action Broad spectrum Divided into groups according to their antimicrobial activity

27. Cephalosporins: First Generation cephalexin (Keflex) cefazolin (Ancef) cefadroxil(Duricef) Good gram-positive coverage Poor gram-negative coverage

28. Cephalosporins: First Generation (cont’d) Used for surgical prophylaxis, URIs, otitis media cefazoline: IV or PO (Ancef) cephalexin: PO (Keflex)

29. Cephalosporins: Second Generation Good gram-positive coverage Better gram-negative coverage than first generation cefaclor cefprozil cefoxitin cefuroxime cefotetan 

30. Cephalosporins: Second Generation (cont’d) cefoxitin: IV and IM Used prophylactically for abdominal or colorectal surgeries Also kills anaerobes cefuroxime: PO Surgical prophylaxis Does not kill anaerobes

31. Cephalosporins: Third Generation Most potent group against gram-negative Less active against gram-positive cefixime cefotaxime ceftizoxime ceftriaxone ceftazidime

32. Cephalosporins: Third Generation (cont’d) cefixime Only oral third-generation agent Best of available oral cephalosporins against gram-negative Tablet and suspension ceftriaxone IV and IM, long half-life, once-a-day administration Easily passes meninges and diffused into CSF to treat CNS infections

33. Cephalosporins: Fourth Generation cefepime Newest cephalosporin agents Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria

34. Cephalosporins: Side Effects Similar to penicillins

35. Macrolides erythromycin azithromycin clarithromycin

36. Macrolides:Mechanism of Action Prevent protein synthesis within bacterial cells Bacteria will eventually die

37. Macrolides: Indications Strep infections Streptococcus pyogenes (group A beta-hemolytic streptococci) Mild to moderate URI Haemophilus influenzae Spirochetal infections Syphilis and Lyme disease Gonorrhea, Chlamydia, Mycoplasma

38. 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

39. Tetracyclines demeclocycline oxytetracycline tetracycline doxycycline minocycline

40. Tetracyclines (cont’d) Natural and semisynthetic Obtained from cultures of Streptomyces Bacteriostatic—inhibit bacterial growth Inhibit protein synthesis Stop many essential functions of the bacteria

41. Tetracyclines (cont’d) Bind to Ca2+ and Mg2+ and Al3+ ions to form insoluble complexes Thus, dairy products, antacids, and iron salts reduce absorption of tetracyclines

42. Tetracyclines: Indications 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

43. 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

44. Tetracyclines: Side Effects (cont’d) Alteration in intestinal flora may result in: Superinfection (overgrowth of nonsusceptible organisms such as Candida) Diarrhea Pseudomembranous colitis

45. Tetracyclines: Side Effects (cont’d) May also cause: Vaginal moniliasis Gastric upset Enterocolitis Maculopapular rash

46. Aminoglycosides gentamicin neomycin streptomycin tobramycin amikacin

47. Aminoglycosides (cont’d) Natural and semisynthetic Produced from Streptomyces Poor oral absorption; no PO forms Potent antibiotics with serious toxicities Bactericidal; prevents protein synthesis Kill mostly gram-negative; some gram-positive also

48. Aminoglycosides: Indications 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

49. Aminoglycosides: Indications (cont’d) All aminoglycosides are poorly absorbed through the GI tract, and given parenterally Exception: neomycin Given orally to decontaminate the GI tract before surgical procedures Also used as an enema for this purpose

50. Aminoglycosides: Agents 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

51. Aminoglycosides: Side Effects Ototoxicity and nephrotoxicity are the most significant Headache Paresthesia Neuromuscular blockade Dizziness  Vertigo Skin rash Fever Superinfections

52. Quinolones ciprofloxacin norfloxacin ofloxacin levofloxacin gatifloxacin

53. Quinolones (cont’d) Excellent oral absorption Absorption reduced by antacids First oral antibiotics effective against gram-negative bacteria

54. 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

55. Quinolones: Indications Lower respiratory tract infections Bone and joint infections Infectious diarrhea Urinary tract infections Skin infections Sexually transmitted diseases Anthrax

56. Quinolones: Indications Lower respiratory tract infections Bone and joint infections Infectious diarrhea Urinary tract infections Skin infections Sexually transmitted diseases Anthrax

57. Quinolones: Side Effects Body System Effects CNS Headache, dizziness, fatigue, depression, restlessness GI Nausea, vomiting, diarrhea, constipation, thrush, increased liver function studies

58. Quinolones: Side Effects (cont’d) Body System Effects Integumentary Rash, pruritus, urticaria, flushing, photosensitivity (with lomefloxacin) Other Fever, chills, blurred vision, tinnitus

59. Other Antibiotics clindamycin (MRSA) Metronidazole(anaerobes) nitrofurantoin (uncomplicated UTI)

60. Other Antibiotics (cont’d) vancomycin Natural, bactericidal antibiotic Destroys cell wall Treatment of choice for MRSA, and other gram-positive infections Must monitor blood levels to ensure therapeutic levels and prevent toxicity May cause ototoxicity and nephrotoxicity

61. Other Antibiotics (cont’d) vancomycin (cont’d) Should be infused over 60 minutes Monitor IV site closely Redman’s syndrome may occur Decreased BP, flushing of neck and face Antihistamine may be ordered to reduce these effects Ensure adequate hydration (2 L fluids/ 24 hr) if not contraindicated to prevent nephrotoxicity

62. Antibiotics: Nursing Implications Before beginning therapy, assess drug allergies; hepatic, liver, and cardiac function; and other lab studies Be sure to obtain thorough client 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

63. Nursing Implications It is recommended to obtain cultures from appropriate sites BEFORE beginning antibiotic therapy

64. Nursing Implications (cont’d) Clients 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

65. Nursing Implications (cont’d) For safety reasons, check the name of the medication carefully because there are many agents that sound alike or have similar spellings

66. Nursing Implications (cont’d) 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 180 to 240 mL of water

67. Nursing Implications (cont’d) 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 180 to 240 mL of water

68. Nursing Implications (cont’d) 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 180 to 240 mL of water

69. Nursing Implications (cont’d) Sulfonamides Should be taken with at least 2000 mL of fluid per day, unless contraindicated Due to photosensitivity, avoid sunlight and tanning beds These agents reduce the effectiveness of oral contraceptives Oral forms should be taken with food or milk to reduce GI upset

70. Nursing Implications (cont’d) Penicillins Any client 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

71. Nursing Implications (cont’d) 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 a disulfiram-like reaction when taken with alcohol

72. Nursing Implications (cont’d) 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

73. Nursing Implications (cont’d) 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 180 to 240 mL of fluid, preferably water Due to photosensitivity, avoid sunlight and tanning beds

74. Nursing Implications (cont’d) 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

75. Nursing Implications (cont’d) Quinolones Should be taken with at least 3 L of fluid per day, unless otherwise specified Intake of alkaline foods and drugs, such as antacids, dairy products, peanuts, and sodium bicarbonate should be limited

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. Figure 38-1 Virus replication. Some viruses integrate into host chromosomes with development of latency. (Modified from Brody, T.M., Larner, J., & Minneman, K.P. (1998). Human pharmacology: molecular to clinical (3rd ed.). St. Louis, MO: Mosby.)

78. Understanding Viruses (cont’d) Viruses are difficult to kill because they live inside human cells Any drug that kills a virus may also kill human cells

79. Viral Infections Competent immune system: Best response to viral infections A well-functioning immune system will eliminate or effectively destroy virus replication

80. Viral Infections (cont’d) Immunocompromised clients have frequent viral infections Cancer clients, especially leukemia or lymphoma Transplant clients, due to pharmacological therapy AIDS clients, disease attacks immune system

81. Antivirals Viruses killed by current antiviral therapy Cytomegalovirus (CMV) Hepatitis viruses Herpes viruses Human immunodeficiency virus (HIV) Influenza viruses (the “flu”) Respiratory syncytial virus (RSV)

82. Antivirals (cont’d) 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

83. Antiviral Medications Antiviral agents Used to treat infections caused by viruses other than HIV Antiretroviral agents Used to treat infections caused by HIV, the virus that causes AIDS

84. Antiviral Agents: Nonretroviral Mechanism of action Inhibit viral replication Used to treat non-HIV viral infections Influenza viruses HSV, VZV (another herpes virus) CMV Hepatitis A, B, C (HAV, HBV, HCV)

85. HIV Human immunodeficiency virus infection ELISA (enzyme-linked immunosorbent assay) Detects HIV exposure based on presence of human antibodies to the virus in the blood Retrovirus Transmitted by: Sexual activity, intravenous drug use, perinatally from mother to child

86. Natural History of HIV Infection Primary acute infection Asymptomatic infection Early symptomatic infection Advanced immunodeficiency with opportunistic complications

87. Opportunistic Infections Protozoal Toxoplasmosis of the brain, others Fungal Candidiasis of the lungs, esophagus, trachea PCP, others Viral CMV disease, HSV infection, others

88. Opportunistic Infections (cont’d) Bacterial Various mycobacterial infections, others Opportunistic neoplasias Kaposi’s sarcoma, others Others

89. Antiretroviral Agents (cont’d) Reverse transcriptase inhibitors (RTIs) Block activity of the enzyme reverse transcriptase, preventing production of new viral DNA Protease inhibitors (PIs) Inhibit the protease retroviral enzyme, preventing viral replication Fusion inhibitors Inhibit viral fusion, preventing viral replication

90. Antiretroviral Agents:Side Effects Numerous and vary with each agent Drug therapy may need to be modified because of side effects Goal is to find the regimen that will best control the infection with a tolerable side effect profile Medication regimens change during the course of the illness

91. 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

92. Nursing Implications Be sure to teach proper application technique for ointments, aerosol powders, etc. Emphasize handwashing before and after administration of medications to prevent site contamination and spread of infection Clients should wear a glove or finger cot when applying ointments or solutions to affected areas

93. Nursing Implications (cont’d) Instruct clients to consult their physician before taking any other medication, including OTCs Emphasize the importance of good hygiene Inform clients that antiviral agents are not cures but do help to manage symptoms

94. Nursing Implications (cont’d) Instruct clients on the importance of taking these medications exactly as prescribed and for the full course of treatment Monitor for side effects Effects are varied and specific to each agent

95. Nursing Implications (cont’d) 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 flulike symptoms, decreased frequency of herpes-like flare-ups,or crusting over of herpetic lesions

96. Antituberculous Agents Tuberculosis (TB) Caused by Mycobacterium tuberculosis Antituberculous agents treat all forms of Mycobacterium

97. Tuberculosis Tuberculosis (abbreviated as TB for Tubercle Bacillus is a common and deadly infectious disease caused by the mycobacterium tuberculosis Symptoms include a productive, prolonged cough of more than three weeks duration, chest pain, and coughing up blood. Systemic symptoms include fever, chills, night sweats, appetite loss, weight loss, paling, and those afflicted are often easily fatigued

98. Mycobacterium Infections Common infection sites Lung (primary site) Brain Bone Liver Kidney

99. Mycobacterium Infections (cont’d) Aerobic bacillus Passed from infected: Humans Cows (bovine) Birds (avian)

100. Mycobacterium Infections (cont’d) Tubercle bacilli are conveyed by droplets Droplets are expelled by coughing or sneezing, then gain entry into the body by inhalation Tubercle bacilli then spread to other body organs via blood and lymphatic systems Tubercle bacilli may become dormant, or walled off by calcified or fibrous tissue

101. Antituberculous Agents First-Line Agents isoniazid* INH ethambutol pyrazinamide (PZA) rifampin streptomycin *Most frequently used Second-Line Agents capreomycin cycloserine ethionamide kanamycin para-aminosalicyclic acid (PAS)

102. Mechanism of Action Three groups Protein wall synthesis inhibitors (streptomycin, kanamycin, capreomycin, rifampin, rifabutin) Cell wall synthesis inhibitors (cycloserine, ethionamide, isoniazid) Other mechanisms of action

103. Isoniazid (INH) Drug of choice for TB Resistant strains of Mycobacterium emerging Metabolized in the liver through acetylation—watch for “slow acetylators” Used alone or in combination with other agents

104. Indications Used for the prophylaxis or treatment of TB

105. Antituberculous Therapy Effectiveness depends upon: Type of infection Adequate dosing Sufficient duration of treatment Drug compliance Selection of an effective drug combination

106. Antituberculous Therapy (cont’d) Problems Drug-resistant organisms Drug toxicity Client noncompliance

107. Side Effects INH– Peripheral neuritis, hepatotoxicity Ethambutol– Retrobulbar neuritis, blindness Rifampin– Hepatitis, discoloration of urine, stools

108. Nursing Implications Obtain a thorough medical history and assessment Perform liver function studies in clients who are to receive isoniazid or rifampin (especially in elderly clients or those who use alcohol daily) Assess for contraindications to the various agents, conditions for cautious use, and potential drug interactions

109. Nursing Implications (cont’d) Client education is critical Therapy may last for up to 24 months Take medications exactly as ordered, at the same time every day Emphasize the importance of strict compliance to regimen for improvement of condition or cure

110. Nursing Implications (cont’d) Client education is critical (cont’d) Remind clients that they are contagious during the initial period of their illness—instruct in proper hygiene and prevention of the spread of infected droplets Emphasize to clients to take care of themselves, including adequate nutrition and rest

111. Nursing Implications (cont’d) Clients should not consume alcohol while on these medications or take other medications, including OTC, unless they check with their physician Diabetic clients taking INH should monitor blood glucose levels because hyperglycemia may occur INH and rifampin cause oral contraceptives to become ineffective; another form of birth control will be needed

112. Nursing Implications (cont’d) Clients who are taking rifampin should be told that their urine, stool, saliva, sputum, sweat, or tears may become reddish orange; even contact lenses may be stained Pyridoxine may be needed to combat neurologic side effects associated with INH therapy Oral preparations may be given with meals to reduce GI upset, even though recommendations are to take them 1 hour before or 2 hours after meals

113. Nursing Implications (cont’d) Monitor for side effects Instruct clients on the side effects that should be reported to the physician immediately These include fatigue, nausea, vomiting, numbness and tingling of the extremities, fever, loss of appetite, depression, jaundice

114. Nursing Implications (cont’d) Monitor for therapeutic effects Decrease in symptoms of TB, such as cough and fever Laboratory studies (culture and sensitivity tests) and CXR should confirm clinical findings Watch for lack of clinical response to therapy, indicating possible drug resistance

115. Antifungal Agents: Definition Drugs used to treat infections caused by fungi Systemic Topical

116. Fungi Large and diverse group of micro-organisms Broken down into yeasts and moulds Fungal infections also known as mycosis Some fungi are part of the normal flora of the skin, mouth, intestines, vagina

117. Yeasts Single-cell fungi Reproduce by budding Can be used for Baking Alcoholic beverages

118. Moulds Multicellular Characterized by long, branching filaments called hyphae

119. Mycotic Infections Four general types Cutaneous Subcutaneous Superficial, most Systemic* *Can be life threatening *Usually occur in immunocompromised host

120. Mycotic Infections (cont’d) Candida albicans Due to antibiotic therapy, antineoplastics, or immunosuppressants (corticosteroids) May result in overgrowth and systemic infections In the mouth Oral candidiasis or thrush Newborn infants and immunocompromised clients Vaginal candidiasis “Yeast infection” Pregnancy, diabetes mellitus, oral contraceptives

121. Antifungal Agents Systemic amphotericin B, fluconazole, ketoconazole, itraconazole Topical Examples: clotrimazole, miconazole, nystatin

122. Indications Systemic and topical fungal infections Agent of choice for the treatment of many severe systemic fungal infections is amphotericin B Choice of agent depends on type and location of infection

123. Side Effects: Amphotericin B Fever Headache Malaise Hypotension Muscle and joint pain Lowered potassium levels Main concerns: Renal toxicity Neurotoxicity: seizures and paresthesias Chills Dysrhythmias Nausea Anorexia

124. Antifungal Agents: Side Effects (cont’d) Fluconazole Nausea, vomiting, diarrhea, stomach pain Increased liver function studies Griseofulvin Rash, urticaria, headache, nausea, vomiting, anorexia, others

125. Nursing Implications Follow manufacturer’s directions carefully for reconstitution and administration Monitor VS of clients receiving IV infusions every 15 to 30 minutes During IV infusions, monitor I&O and urinalysis findings to identify adverse renal effects

126. Nursing Implications (cont’d) 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

127. Nursing Implications (cont’d) Monitor for therapeutic effects Easing of the symptoms of infection Improved energy levels Normal vital signs, including temperature

128. Protozoal Infections Parasitic protozoa: live in or on humans Malaria Leishmaniasis Amoebiasis Giardiasis Trichomoniasis

129. Malaria Caused by Plasmodium protozoa Four different Plasmodium species Cause: the bite of an infected adult female anopheline mosquito Can also be transmitted by infected individuals via blood transfusion, congenitally, or infected needles by individuals that abuse drugs

130. 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 effective only during the asexual cycle

131. Antimalarial Agents Attack the parasite during the asexual phase, when it is vulnerable Erythrocytic phase drugs: chloroquine, hydroxychloroquine, quinine, mefloquine Primaquine: kills parasite in both phases May be used together for synergistic or additive killing power

132. Antimalarial Agents (cont’d) 4-aminoquinolines for prevention and treatment atovaquone/proquanil chemoprophylaxis and first-line for uncomplicated multidrug resistant malaria quinine for treatment

133. Antimalarials: Drug Effects Kill parasitic organisms Chloroquine and hydroxychloroquine also have anti-inflammatory effects

134. Antimalarials: Indications 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

135. Antimalarials: Side Effects Many side effects for the various agents Primarily gastrointestinal: nausea, vomiting, diarrhea, anorexia, and abdominal pain

136. Antiprotozoals atovaquone metronidazole pentamidine paromomycin

137. Protozoal Infections Amoebiasis Giardiasis Pneumocystosis Toxoplasmosis Trichomoniasis

138. Protozoal Infections (cont’d) Transmission Person to person Ingestion of contaminated water or food Direct contact with the parasite Insect bite (mosquito or tick)

139. Protozoal Infections (cont’d) Clients with compromised immune systems are at risk for acquiring these infections Taking immunosuppressive drugs after a transplant Leukemia AIDS Protozoal infections are often fatal in these cases

140. Table 41-3 Types of protozoal infections

141. Antiprotozoals: Mechanism of Action and Indications (cont’d) metronidazole Disruption of DNA synthesis as well as nucleic acid synthesis Bactericidal, amoebicidal, trichomonacidal Used for treatment of trichomoniasis, amoebiasis, giardiasis, anaerobic infections, and antibiotic-associated pseudomembranous colitis

142. Antiprotozoals: Side Effects atovaquone Nausea, vomiting, diarrhea, anorexia, many others metronidazole Metallic taste, nausea, vomiting, diarrhea, abdominal cramps, many others

143. Anthelmintics Drugs used to treat parasitic worm infections: helminthic infections Unlike protozoa, helminths are large and have complex cellular structures Drug treatment is specific

144. Anthelmintics (cont’d) mebendazole niclosamide praziquantel

145. Anthelmintics (cont’d) It is 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) Platyhelminthes (flatworm)

146. Table 41-8 Helminthic infections

147. Anthelmintics: Side Effects praziquantel Nausea, vomiting, diarrhea, dizziness, headache mebendazole Diarrhea, abdominal pain, myelosuppression

148. Antimalarial, Antiprotozoal, Anthelmintic 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

149. Some agents may cause the urine to have an asparagus-like odour, or cause an unusual skin odour, or a metallic taste; be sure to warn the client 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; atovaquone should be taken with food, often fatty food, to increase plasma drug levels Antimalarial, Antiprotozoal, Anthelmintic Agents: Nursing Implications (cont’d)

150. 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

151. Antimalarial Agents: Nursing Implications (cont’d) Instruct client to notify physician immediately if ringing in the ears, hearing decrease, visual difficulties, nausea, vomiting, profuse diarrhea, or abdominal pain occurs Alert clients to the possible recurrence of the symptoms of malaria so that they will know to seek immediate treatment

152. Antimalarial, Antiprotozoal, Anthelmintic Agents: Nursing Implications Monitor for side effects Ensure that clients know the side effects that should be reported Monitor for therapeutic effects and adverse effects with long-term therapy