Antimicrobials - DISINFECTION AND STERILZATION

Antimicrobials

DHYG 139 PharmacologyHeidi Emmerling, RDH, PhD

Fall 2010

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Antimicrobial AgentsP 139

DHYG 139 Pharmacology Heidi

Emmerling, RDH, PhD Fall 2010

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Antimicrobial Agents

An antimicrobial agent suppresses the growth or destroys microorganisms.



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The categories of antimicrobial agents:



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The categories of antimicrobial agents:• Antibacterial agents

AntibioticsSulfonamides



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An antimicrobial agent suppress the growth or destroys microorganisms.

The categories of antimicrobial agents:• Antibacterial agents

Antibiotics Sulfonamides

• Antifungal agents• Antiviral agents



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Antibiotics



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Antibiotics

Chemical substances which were originally produced by micro-organisms and either retard the growth of other microorganisms or result in their death.



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Antibiotics

Antibiotics can exert their effects in 4 different ways:



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Antibiotics

1. Inhibition of bacterial cell wall synthesis



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Antibiotics

1. Inhibition of bacterial cell wall synthesis2. Alteration of bacterial cell membrane

permeability



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Antibiotics


permeability3. Alteration of bacterial synthesis of

cellular components



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Antibiotics


permeability3. Alteration of bacterial synthesis of

cellular components4. Inhibition of bacterial cell metabolism



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Resistance of bacteria to antibiotics

• Natural resistance – occurs before exposure to an antibiotic



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• Acquired resistance – occurs after exposure to the antibiotic



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• Acquired resistance – Occurs after exposure to the antibiotic– A low dose or short treatment may develop

resistant strains



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• Acquired resistance – occurs after exposure to the antibiotic– A low dose or short treatment may develop

resistant strains– If not all the bacteria are destroyed, the next

infection will be by offspring from the most-resistant organisms



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Spectrum of Activity

• Different antibiotics will be effective against different bacteria



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• Some antibiotics are very specific and are only effective against a limited type of bacteria. (i.e. Only Gram + bacteria)



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• Some antibiotics are very specific and are only effective against a limited type of bacteria. (i.e. Only Gram + bacteria)– These are called limited spectrum antibiotics



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• Some antibiotics are very specific and are only effective against a limited type of bacteria. (i.e. Only Gram + bacteria)– These are called limited spectrum antibiotics

• Some antibiotics have a broad spectrum of activity and are effective against a broader range of bacteria.



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• Some antibiotics are very specific and are only effective against a limited type of bacteria. (i.e. Only Gram + bacteria)– These are called limited-spectrum antibiotics

• Some antibiotics have a broad spectrum of activity and are effective against a broader range of bacteria.– These are called broad-spectrum antibiotics



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• Limited-spectrum antibiotics are more effective against a particular bacteria than are the broad-spectrum antibiotics.



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• Limited-spectrum antibiotics and more effective against a particular bacteria than are the broad-spectrum antibiotics.

What?????



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A limited-spectrum antibiotic is effective against only A Limited-Spectrum

(Bacteria) A B C D



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A limited-spectrum antibiotic A broad-spectrum antibiotic is effective against only A is effective against A B C D Limited-spectrum Broad-spectrum

(Bacteria) A B C D



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A limited-Spectrum antibiotic A broad-spectrum antibiotic is effective against only A is effective against A B C D Limited-spectrum Broad-spectrum

A B C D

Although the broad-spectrum does kill bacterial A, the limited-spectrum antibiotic will do a much better and faster job and would be the drug-of-choice.



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Penicillin P 140



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Penicillin

• The first antibiotic discovered



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Penicillin

• The first antibiotic discovered• Discovered by Alexander Fleming in

1928



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Penicillin


1928• It’s still the most effective antibiotic

we have



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Penicillin


1928• It’s still the most effective antibiotic

we have• It’s the most widely used antibiotic in

dentistry



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Penicillin

• Spectrum of Activity



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Penicillin

• Spectrum of Activity– Gram (+) organisms (most dental infections)

• Staph• Strep• Pneumococcus



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Penicillin

• Spectrum of Activity– Gram (+) organisms (most dental infections)

• Staph• Strep• Pneumococcus

– Gram (-) organisms• Gonorrhea• Syphilis



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Penicillin

• Preparations



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Penicillin

• Preparations– Category 1 (Penicillin G)– Category 2 (Penicillin V)– Category 3 (Penicillinase-

resistant synthetics)– Category 4 (Broader-spectrum

Penicillin)– Category 5 (New synthetic

broad- spectrum penicillin)



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Penicillin

• Category 1 Penicillin G



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Penicillin

• Category 1 Penicillin G– The 1st form of penicillin discovered



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Penicillin

• Category 1 Penicillin G– The 1st form of penicillin discovered– Still the most effective form



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Penicillin

• Category 1 Penicillin G– The 1st form of penicillin discovered– Still the most effective form– Unstable in the stomach, so it must be

injected



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Penicillin

• Category 1 Penicillin G– The 1st form of penicillin discovered– Still the most effective form– Unstable in the stomach, so it must be

injected– Comes in many different forms:

• Potassium Penicillin G– Reaches blood levels fast/ drops fast

• Procaine Penicillin G– Reaches blood levels slow/drops slow



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Penicillin

• Category 2 Penicillin V



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Penicillin

• Category 2 Penicillin V– Stable in the stomach so taken orally



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Penicillin

• Category 2 Penicillin V– Stable in the stomach so taken orally– Can be injected, but G is better



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Penicillin

• Category 2 Penicillin V– Stable in the stomach so taken orally– Can be injected, but G is better– Popular in dentistry



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Penicillin

• Category 2 Penicillin V– Stable in the stomach so taken orally– Can be injected, but G is better– Popular in dentistry– Infections that require immediate

attention:• 1st give Pencillin G• Then follow-up for the long-term with

Pencillin V orally (7-10 days)



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Penicillin

• Category 3 Penicillinase-resistant Synthetics



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Penicillin

• Category 3 Penicillinase-resistant Synthetics– Penicillinase is a chemical produced by some

bacteria that destroys penicillin



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Penicillin


bacteria that destroys penicillin– Therefore normal penicillin is ineffective



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Penicillin


bacteria that destroys penicillin– Therefore normal penicillin is ineffective– These synthetics are effective against those

bacteria that produce penicillinase



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Penicillin



bacteria that produce penicillinase– They can be used for all bacterial infections but

are not as effective as G or V for non-penicillinase producing bacteria.



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Penicillin



bacteria that produce penicillinase– They can be used for all bacterial infections but

are not as effective as G or V for non-penicillinase producing bacteria.

– Examples:• Methicillin Oxacillin Nafcillin



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Penicillin P 141

• Category 4 Broader-spectrum Penicillins



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Penicillin


– These have a wider spectrum than other penicillins



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Penicillin


– These have a wider spectrum than other penicillins

– Are effective against organisms affected by the category 1 & 2 penicillins plus more Gram (-) organisms



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Penicillin


– These have a wider spectrum that other penicillins

– Are effective against organisms effected by the category 1&2 penicillins plus more gram (-) organisms

– Examples:



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Penicillin

• Category 4 Broader-spectrum Penicillins– Amoxicillin

• Becoming very popular because:– Reaches high blood levels– Better absorption from the stomach even with

presence of food.– Need less frequent dosing (TID not QID)



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Penicillin

• Category 4 Broader-spectrum Penicillins– Amoxicillin

• Becoming very popular because:– Reaches high blood levels– Better absorption from the stomach even with

presence of food.– Need less frequent dosing (TID not QID)

– Ampicillin• Used on small children• Will deactivate the birth control pill



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Penicillin

• Category 5 (New Synthetic Broad- spectrum Penicillin)



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Penicillin

• Category 5 – These are less effective than the other

penicillins– They are very expensive



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Penicillin


penicillins– They are very expensive– They are used when other penicillins (or

other antibiotics) are ineffective



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Penicillin


penicillins– They are very expensive– They are used when other penicillins (or

other antibiotics) are ineffective– Examples:

• Ticarcillin• Piperacillin



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Penicillin

• Limited-spectrum vs Broad-spectrum



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Penicillin

• Limited-spectrum vs Broad-spectrumEach category of penicillin has a rather limited-spectrum, with some categories (i.e.Category 4) having a somewhat wider spectrum.



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Penicillin

• Limited-spectrum vs Broad-spectrumEach category of penicillin has a rather limited-spectrum, with some categories (i.e.Category 4) having a somewhat wider spectrum.

• However, penicillin as a whole (category 1-5) has a broad-spectrum of activity



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Toxicity of Penicillin



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• Allergic reactions are the only real toxicity



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• Allergic reactions are the only real toxicity– First exposure

• A mild reaction• Skin rash, itching, etc.



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• Allergic reactions are the only real toxicity– First exposure

• A mild reaction• Skin rash, itching, etc.

– Second exposure• Anaphylactic shock• Asthmatic breathing and drop in BP



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Cephalosporins



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Cephalosporins

• A broader-spectrum than penicillin



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Cephalosporins

• A broader-spectrum than penicillin• These drugs are structurally similar to

penicillin.– In 10% of the cases, an individual with an allergy to

cephalosporins will also be allergic to penicillin



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Cephalosporins

• A broader-spectrum than penicillin• These drugs are structurally similar to

penicillin.– In 10% of the cases, an individual with an allergy to

cephalosporins will also be allergic to penicillin

• Spectrum of activity– Gram (+) & (-)– Penicillin-resistant Staph– E. Coli– Klebsiella



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Cephalosporins

• More side effects than penicillin– Renal damage– Increased RBC hemolysis



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Cephalosporins


• Many believe this is a better drug for systemic infections than oral infections



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Cephalosporins


• Many believe this is a better drug for systemic infections than oral infections

• Example:– Cephalexin– Keflex



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Erythromycin



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Erythromycin P142

• A limited-spectrum antibiotic(slightly greater than Penicillin V)

• Low toxicity



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Erythromycin

• A limited-spectrum antibiotic(slightly greater than Penicillin V)

• Low toxicity• Gastrointestinal upset occurs rarely• Resistance develops slowly



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Lincomycin & Clindamycin



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• Developed in 1962• Reserved for patients who cannot take

penicillin, erythromycin or cephalosporins



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penicillin, erythromycin or cephalosporins• Not the drug of choice for dental infections• Expensive



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penicillin, erythromycin or cephalosporins• Not the drug of choice for dental infections• Expensive• A substitute for penicillin in premedication

conditions• Spectrum of activity:

– Similar to erythromycin



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• Has good bone-penetrating ability, therefore used to treat osteomyelitis



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• Side effects:– Diarrhea occurs frequently– Severe hemorrhagic colitis (can be fatal)– Glossitis



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• Side effects:– Diarrhea occurs frequently– Severe hemorrhagic colitis (can be fatal)– Glossitis

• Example:– Cleocin (clindamycin)– Lincocin (lincomycin)



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Tetracycline



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Tetracycline

• A true broad-spectrum antibiotic



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Tetracycline

• A true broad-spectrum antibiotic• Used for many non-specific infections• Little indication for oral use (except for the

direct gingival sulcus applications)



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Tetracycline

• A true broad-spectrum antibiotic• Used for many non-specific infections• Little indication for oral use (except for the

direct gingival sulcus applications)• Isolate in fast growing tissues:

– Bone (results in stained bone)

– Teeth (results in stained calcifying teeth)

– Tumors



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Tetracycline

• Resistant strains develop rapidly



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Tetracycline

• Resistant strains develop rapidly• Toxicity:

– GI upset– Photosensitivity– Prolonged bleed time



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Tetracycline

• Resistant strains develop rapidly• Toxicity:

– GI upset– Photosensitivity– Prolonged bleed time

• UsesGonorrhea InfluenzaDysentery Typhoid feverSkin acne Chronic periodontal disease

(intra-sulcular)



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Tetracycline

• Preparations– Chlortetracycline (Aureomycin)– Oxytetracycline (Terramycin)– Tetracycline (Achromycin)



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Flagyl (Metronidazole)



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• Has a very limited spectrum of activity– Used for HIV+ individuals; – less chance of fungal infections



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• Has a very limited spectrum of activity– Used for HIV+ individuals; – less chance of fungal infections

• Used for anaerobic bacteria



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Anti-tuberculosis Antibiotics



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• TB is difficult to treat because:– The patient’s immune system is usually

compromised– Resistant strains develop rapidly



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compromised– Resistant strains develop rapidly– Antibiotics are only bacteriostatic

• To be effective, antibiotics are used in small doses over a long period of time



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compromised– Resistant strains develop rapidly– Antibiotics are only bacteriostatic

• To be effective antibiotics are used in small doses over a long period of time

– Non-compliance is an issue



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• Antibiotics are usually given as a cocktail (multiple drugs)



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• Antibiotics are usually given as a cocktail (multiple drugs)

• Antibiotics used today:– Isoniazid (used for 9-12 months)– Rifampin (used for 9-12 months)– Pyrazinamide (used for 1st 2 months)



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Topical Antibiotics



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Topical Antibiotics

• There is little evidence that these have any positive effect

• Examples:– Neomycin– Bacitracin



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Sulfonamides



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Sulfonamides

• Developed in 1908• No use for intraoral infections• These are bacteriostatic only



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Sulfonamides

• Developed in 1908• No use for intraoral infections• These are bacteriostatic only• Used for:

– Urinary-tract infections– Meningococcal meningitis



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Antifungal Drugs



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Antifungal Drugs

1. Nystatin (Mycostatin)



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Antifungal Drugs

1. Nystatin (Mycostatin)• Very effective• Little toxicity



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Antifungal Drugs

1. Nystatin (Mycostatin)• Very effective• Little toxicity• Applied topically or given systemically• Very effective against Candida albicans



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Antifungal Drugs

1. Nystatin (Mycostatin)• Very effective• Little toxicity• Applied topically or given systemically• Very effective against Candida albicans• Vaginal lozenges work better than intraoral

preparations (no sugar)• Dissolve lozenge for 15 minutes 5 times per

day



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Antifungal Drugs

2. Mycelex (Chlotrimazole)• Similar in most aspects with Nystatin



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Antifungal Drugs

2. Mycelex (Chotrimazole)• Similar in most aspects with Nystatin

3. Nizoral• A topical antifungal cream • Used for systemic candidiasis• Used for skin fungal problems



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Antiviral Drugs



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Antiviral Drugs

• Limited success with antiviral drugs because:– A virus is an intracellular parasite– By the time a viral infection becomes noticed,

the virus is well established



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Antiviral Drugs

• Limited success with antiviral drugs because:– A virus is an intracellular parasite– By the time a viral infection becomes noticed,

the virus is well established• The body has begun fighting the virus well

before the antiviral drug is applied.



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Antiviral Drugs

• Limited success with antiviral drugs because:– A virus is an intracellular parasite– by the time a viral infection becomes noticed,

the virus is well established• The body has begun fighting the virus well

before the antiviral drug is applied• In many cases, the body takes care of the

virus: – the antiviral is given too late to be effective



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Antiviral Drugs

1. Acyclovir (most effective antiviral to date)



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Antiviral Drugs

1. Acyclovir• Used with some success on herpes simplex



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Antiviral Drugs

1. Acyclovir• Used with some success on herpes simplex• Comes in three forms:



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Antiviral Drugs


1. Topical ointment (Denavir)• Does tend to shorten the length of a cold sore• It must be started early to be effective



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Antiviral Drugs


1. Topical ointment (Denavir)• Does tend to shorten the length of a cold sore• It must be started early to be effective

2. Oral Tablets• Restricted to serious cases• May decrease incidents and severity



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Antiviral Drugs


1. Topical ointment (Denavir)• Does tend to shorten the length of a “cold sore”• It must be started early to be effective

2. Oral Tablets• Restricted to serious cases• May decrease incidents and severity

3. IV Only on severe viral herpetic invasions



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Antibiotic Premedication P 144



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Antibiotic Premedication

• General (broad) indications



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• General (broad) indications– A patient who is susceptible to endocarditis or

an infection in a prosthetic joint and we are about to manipulate the tissue and cause a bacteremia



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an infection in a prosthetic joint and we are about to manipulate the tissue and will cause a bacteremia

– A patient with reduced resistance to infections



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an infection in a prosthetic joint and we are about to manipulate the tissue and will cause a bacteremia

– A patient with reduced resistance to infections



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• Specific indications



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• Specific indications – Patients with an artificial heart valve



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• Specific indications – Patients with an artificial heart valve– Patients with a history of infective endocarditis



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• Specific indications – Patients with an artificial heart valve– Patients with a history of infective endocarditis– Patients with specific congenital heart defects

• Shunts, conduits, repaired with prosthesis,



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• Specific indications – Patients with an artificial heart valve– Patients with a history of infective endocarditis– Patients with specific congenital heart defects– Patients with a cardiac transplant that develops

a problem with a valve



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• Specific indications – Patients with an artificial heart valve– Patients with a history of infective endocarditis– Patients with specific congenital heart defects– Patients with a cardiac transplant that develops

a problem with a valve– A patient who has had total joint replacement

within two years



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• Indications where antibiotic premedication is not needed:



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• Indications where antibiotic premedication is not needed:– Coronary bypass surgery



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• Indications where antibiotic premedication is not needed:– Coronary bypass surgery– Mitral valve prolapse



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• Indications where antibiotic premedication is not needed:– Coronary bypass surgery– Mitral valve prolapse– History of rheumatic fever w/o valve damage



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• Indications where antibiotic premedication is not needed:– Coronary bypass surgery– Mitral valve prolapse– History of rheumatic fever w/o valve damage– Pacemakers



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• Indications where antibiotic premedication is not needed:– Coronary bypass surgery– Mitral valve prolapse– History of rheumatic fever w/o valve damage– Pacemakers– Heart murmurs– Bicuspid valve disease, clacified aortic stenosis,

certain congenital conditions like ventricular septal defect, hypertrophic cardiomyopathy



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• Indications where antibiotic premedication is not needed:– Artificial joints (knees, hips, etc) after 2

years



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• Indications where antibiotic premedication is not needed:– Artificial joints (knees, hips, etc) after 2

years– People with uncontrolled diabetes



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Drugs Used for Premedication



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• Drug of choice: Amoxicillin



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• Drug of choice: Amoxicillin– Orally– 2000 mg for adult– 50 mg/kg for children



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• For penicillin-allergic patients:



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• For penicillin-allergic patients:– Cephalexin

• Unless they have a history of anaphylactic shock with penicillin

• 2000 mg for adults• 50 mg/kg for kids



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• For penicillin-allergic patients:– Cephalexin

• Unless they have a history of anaphylactic shock with penicillin


– Clindamycin• 600 mg for adults• 20 mg/kg for kids



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• For penicillin-allergic patients:– Azithromycin




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Other Information about Premeds



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• For high-risk patients, always use amoxicillin if possible– i.e. Artificial heart valve



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• A bacteremia is only present for about 15 minutes.



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Other information about premeds


• A bactermia is only present for about 15 minutes. – Don’t give the premedication more than

1 hour before the appointment– Can be effective if given less than 2

hours after the appointmentDHYG 139 Pharmacology Heidi


Antimicrobials - DISINFECTION AND STERILZATION

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