Transcript Analgesics and Antipyretics

Chapter 18
Antimicrobials, Antifungals, and
Antivirals
Common Indications
• Infections due to microorganisms, fungi, viruses
• Disinfectants, germicidal, antiseptics used in
medical clinical areas
Clostridium perfringens.
From Cotran RS, Kumar V, and Collins T (1999): Robbins’ pathologic
basis of disease (6th ed). Philadelphia: Saunders.
Microorganisms
• Microbiology—study of microscopic organisms
– bacteria
– viruses
– parasites
– fungi
– protozoa
• Can be pathogenic (disease-causing) or normal flora
• Can be identified by shape (i.e., cocci, spirilla), gram
staining (positive or negative), or need for oxygen
– aerobic
– anaerobic
– facultative
Antimicrobials
• Destroy microorganisms or inhibit
microorganism growth
• Include:
– antibiotics—natural or synthetic substance
interfering with microbial growth
– bacteriostatics—inhibit bacterial growth
– bactericidal agents—cause death of bacterial cell
Antibiotic Therapy
• Choose carefully based on sensitivity of infecting
organism
• Rarely given preventatively or prophylactically
except in cases of surgery or exposure to
unusual disease
• Narrow-spectrum antibiotics effective against
only a few microorganisms
• Broad-spectrum antibiotics effective against
wide range of microbes
Antibiotic Therapy
• Prescribed only when indicated by a specific
disease
• Fever only a symptom and not reason to begin
therapy
• Antibiotics ineffective for treatment of viral
infections
• Take entire prescribed course
• Disappearance of symptoms does not indicate
infection is gone
Penicillins
• Weaken cell walls causing lysis and death
• Gram-negative bacteria resistant to most
penicillins
• Safest antibiotic available; but patient allergic to
one penicillin considered allergic to all penicillins
• Principal differences among penicillins—
spectrum of antibacterial action, stability in
stomach acids, duration of action
• Effectiveness of birth control pills decreases
when certain penicillins used concurrently
Cephalosporins
• Weaken cell walls, causing death to bacteria
• Closely related to penicillins
• Grouped into 4 generations; each one has
increased activity against gram-negative
bacteria
• Many given parenterally
• If oral, take with food if gastric upset occurs
Cephalosporins
• Carefully watch patients allergic to penicillins
when administering cephalosporins
• Refrigerate suspensions
• Some cannot be combined with alcohol
• Cephalosporins intensify bleeding tendencies
• Many names contain -cef or -ceph in
brand/generic name
Macrolides
• Broad-spectrum antimicrobials
• Names of drugs usually end in –mycin
• Take erythromycin and chloramphenicol on
empty stomach; may be taken with meals if GI
upset occurs
• Erythromycin generally safe; given to patients
with penicillin allergies
Common Macrolides
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erythromycin
EES
Zithromax
Biaxin
Dynabac
TAO
Tetracycline
• First group of broad-spectrum antibiotics
• Adverse reactions—photosensitivity, staining of
developing teeth
• Do not give with calcium supplements, milk
products, iron supplements, magnesiumcontaining laxatives, most antacids
• Names of drugs usually end in -cycline
Aminoglycosides
• Potent bactericidal agents usually reserved for
serious or life-threatening infections
• Nephrotoxic and ototoxic
• Have patients report dizziness, tinnitus,
unsteadiness, hearing loss, oliguria
• Topical use relatively safe
Common Aminoglycosides
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amikacin
gentamicin
kanamycin
neomycin
streptomycin
tobramycin
Quinolone Antimicrobials
• Broad-spectrum antibiotics with mild side effects
• Do not take ciprofloxin with milk products,
antacids, iron supplements, magnesium
laxatives
• Do not give ciprofloxin to children younger than
16–18 years (cartilage damage)
Common Quinolone Antimicrobials
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Cipro
Penetrex
Maxaquin
Levaquin
Noroxin
Floxin
Tequin
Avelox
Miscellaneous Antibiotics
• Vancomycin—toxic; reserved for treating serious
infections in patients allergic to penicillin
• Chloramphenicol—cause serious blood
dyscrasias
• Metronidazole (Flagyl)—used against protozoa,
anaerobic bacteria
• Topical antibiotic preparations usually contain
neomycin, bacitracin, polymyxin B
Sulfonamides (Sulfa Drugs)
• Antibacterials slow growth of bacteria while body
builds its own defenses
• Primarily treat urinary tract infections, in
combination therapy for otitis media
• Take oral sulfonamides with full glass of water
on empty stomach
Sulfonamides (Sulfa Drugs)
• May cause photosensitivity reactions
• Urine should be acidic for optimum
effectiveness
• Take medications for urinary tract infections
for 2 weeks to prevent development of more
resistant infections
• Topical preparations available in ocular forms,
lotions, powders, ointments
Common Sulfonamides
(Sulfa Drugs)
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Gantrisin
Gantanol
Azulfidine
Triple Sulfa
Bactrim
Septra
Sulamyd
Silvadene cream
Urinary Tract Antiseptics
• Agents reduce microbial flora by inhibiting
growth
• Do not achieve effective antibacterial
concentration in blood or tissue
• Usually second choice of drugs after antibiotics
or sulfonamides
• Include nitrofurantoin, methenamine, nalidixic
acid, cinoxacin
Fungal Infections
• Fungi include spore-forming yeasts and molds
thriving on dead plants and animals
• Fungi produce irritating symptoms; normally
controlled by bacteria, immune system
• Fungi prefer moist, warm, dark environment
(feet, crotch, underarm areas)
Fungal Infections
• Many are opportunistic infections (because
immune system cannot fight normal flora)
• Long-term antibiotic or radiation therapy can
create conducive environment
• Most common fungal infections:
– ringworm
– athlete’s foot
– Candida albicans in mouth, vagina
Drugs to Treat Fungal Infections
• Systemic and topical
• Fungicidal (kill fungi) or fungistatic (inhibit fungal
growth)
• Most topical medications available OTC
• Antifungals designed to be used for 4 weeks
(unless used on nails)
Common Antifungal Drugs
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Fungizone
Diflucan
Nizoral
Mycostatin
Lamisil
Lotrimin
Monistat
Terazol
Desenex
Viral Infections
• Viruses—strands of genetic material wrapped in
protein
• Cannot sustain themselves independently; must
rely on host
• Difficult to suppress viral reproduction; host’s
body cells would be harmed also
Drugs to Treat Viral Infections
• Drugs decrease symptoms, do not cure
• Resistance to antiviral drugs major problem
• Drug classifications:
– non-HIV infection medications
– HIV infection medications
Common Non-HIV Antiviral Drugs
• Symmetrel and
Flumadine—Influenza A
• acyclovir (Zovirax)—
herpes simplex, genital
herpes, varicella zoster
infections
• ganciclovir—
cytomegalovirus
HIV Antivirals
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No cure for HIV
Dramatic advances in drug therapy
Health preserved, life prolonged
Multiple drug interactions and side effects
High cost, toxicity
Drug cocktail used; patient must adhere closely
to prescribed dosage schedules
• New drugs prescribed should be agents the
patient has never taken
Antiseptic vs. Disinfectant
• Antiseptic—agent reducing, preventing, or
inhibiting growth of microbial flora of skin and
mucous membranes without necessarily killing
them
• Disinfectant (germicide)—agent decreasing
number of microorganisms on inanimate objects
by killing bacteria
• Sanitization—process of cleaning and removing
dirt