Why study antiinfective agents?
Infection, after pain management, is the dental problem for which drugs are most often prescribed
Types of dental infections:
-Periodontal disease (Biggest problem in adult patients)
-Localized dental infections
-Systemic dental infections
Stages of dental infection "Evolution":
1.) Early stage- Aerobes
2.) Mixed stage- Aerobes and anaerobes
3.) Chronic stage- Anaerobes
If the infection is just beginning in the early stage, what organisms are most likely to be present?
What drug affects both gram-positive cocci and gram-positive and gram-negative anaerobes?
Substances that destroy or suppress the growth or multiplication of bacteria (may be synthetic)
Chemical substances produced by microorganisms that have the capacity, in dilut solutions, to destroy or suppress the growth or multiplication of organisms or prevent their action
Substances that destroy or suppress the growth or multiplication of microorganisms
An invasion of not only the body by pathogenic microorganisms but also a reaction of the tissues to their presence
Minimum inhibitory concentration (MIC)
Lowest concentration needed to inhibit visible growth of an organism on media after 18-24 hours of incubation
Lower the MIC, Higher the potency!!
Infection caused by the proliferation of microorganisms different from those causing the original infection
Superinfection is more often caused by ___ spectrum antibiotics such as ___ and increases when taken for a longer period.
Occurs when the combination of 2 antibiotics produces more effect than would be expected if their individual effects were added
Factors determining likelihood of a microorganism causing an infection:
1.) Disease-producing power of the microorganism (virulence)
2.) Number of organisms present (inoculum)
3.) Resistance of the host (immunologic response)
What involves the exposing of the organism to certain test antibiotics and determining whether the organism is sensitive or resistant?
Natural vs. Acquired resistance
1.) Natural- An organism has always been resistant to an antimicrobial agent because of the bacteria's normal properties
2.) Acquired- An organism that was previously sensitive to an antimicrobial agent develops resistance
The wider te spectrum of the antiinfective agent and the longer the agent is administered, the ____ the chance of superinfection occurring.
Drug interactions of Antiinfective agents:
-Oral contraceptives (reduce effectiveness)
Oral anticoagulants are ____ _ inhibitors, so interferring with the production of ____ _ could ____ the anticoagulant effect.
Vitamin K; Vitamin K; increase
1.) Gastrointestinal complaints
-Stomach pain, increased motility, diarrhea
2.) Pregnancy considerations
3.) Dose forms
4.) Cost (important factor in deciding antibiotic for patient)
What drug has the highest incidence of gastrointestinal complaints of any of the antibiotics?
What happens when the B-lactam ring is broken?
(Such as in the presence of penicillinase) The antimicrobial activity of the compound is lost
Pharmacokinetics of Penicillins
-Metabolized by hydrolysis in the liver
-Undergoes tubular secretion in the kidney
-Elimination half-life for both G and V is 0.5 hours
Mechanism of action of Penicillins
-Very potent bactericidal agent
-Attached to penicillin-binding proteins (PBPs) on the bacterial cell membrane
Penicillin inhibits the formation of ___ ___. This destroys cell wall integrity and leads to ___ of the cell.
Adverse reactions of Penicillins
1.) Toxicity- low to almost nonexistent
2.) Allergy and hypersensitivity
Types of allergic reactions to penicillin
-Delayed serum sickness
The use of penicillin in dentistry results from its:
-Lack of toxicity
-Spectrum of action
What is the usual adult dose of penicillin V?
500 mg 4x/day for a min. of 5 days and preferably 7-10 days
Penicillinase-Resistant penicillins should be reserved for use against only penicillinase-producing ____.
Ampicillins and amoxicillin is mixed with _____ ___, a B-lactamase inhibitor (Augmentin), this combines with and inhibits B-lactamases produced by bacteria.
Pharmacokinetics of Erythromycin
-Broken down in gastric fluid
-Spectrum closely resembles that of penicillin
Adverse reactions of Erythromycin
Allergic reactions are uncommon!
Azithromycin and Clarithromycin
-Activity against gram-positive and negative aerobes
Pharmacokinetics of tetracyclines
-Half-life is 2 hours
-Stored in dentin and enamel of unerupted teeth and concentrated in GCF
Adverse reactions of tetracyclines
-Gastrointesting effects (GI distress is common)
-Effects on teeth and bones
What is Minocycline (adverse reaction of tetracyclines)?
CNS side effects including lightheadedness, dizziness and vertigo
What should not be taken within 2 hours of ingesting tetracycline?
Dairy products containing calcium, antacids, and mineral supplements
Drug interactions of tetracyclines
-Enhanced effect of other drugs
-Reduced doxycycline effect
-General antibiotic interactions
The most commonly observed side effects of clindamycin are:
The development of pseudomembranous colitis (PMC), also known as ____ ____ ___, has been a more serious consequence associated with clindamycin. It is characterized by severe, persistent diarrhea and the passage of blood
Antibioticassociated Colitis (AAC)
Adverse reactions of Metronidazole
-GI tract effects- most common adverse reaction = 12%
-Oral effects (xerostomia, unpleasant metallic taste)
What should be avoided during Metronidazole administration and for 1 day after therapy is ceased?
Uses of Metronidazole:
1.) Medical- Useful because of its anaerobic spectrum
2.) Dental- Tx of many perio infections
Pharmacokinetics of Cephalosporins
-Half-life 50-240 minutes
Structurally related to the penicillins!
Adverse reactions of Cephalosporins
-GI effects- most common
-Impair hemostasis and disulfiram-like-reaction-parenteral (injections)
Various types of hypersensitivity reactions have been reportred in approx. ___% of patients receiving cephalosporins.
Use of cephalosporins
Prophylaxis for patients with "at-risk" joints who are undergoing dental procedures likely to produce bleeding
Rational use of antiinfective agents:
1.) Stage I- Acute infection (Gram + aerobes)
2.) Stage II- Mixed infection (Aerobes and anaerobes)
3.) Stage III- Chronic infection (Anaerobes)
Why an antiinfective may be ineffective:
-Concentration did not reach site of infection
-Host defense inadequate
Adverse reactions of sulfonamides
-Allergic skin reactions
-Possibility of renal crystallization
*DRINK PLENTY OF WATER!!*
Because of the problem of resistance, at least ___ drugs are administered concurrently in all active cases.
-Half-life is 1.5-5 hours
-Most common adverse reaction if GI
-Causes a red-orange color to body fluids
Topical antibiotics include a combination of...
Neosporin and triple antibiotic ointment
-Used topically for scratches
Factors to consider for using prophylactic antibiotics:
1.) The specific dental procedure being performed
2.) The cardiac and medical condition of the patient
3.) The drug and dose that may be needed
What is the most common oral fungus?
Fungal infections are often difficult to treat
-Taken orally it is poorly absorbed from the GI tract
-Available as aqueous suspension or lozenge
-Binds to phospholipids in cell membrane which produces an alteration of cell membrane permeability
-Alters cellular membranes and interferes with intracellular enzymes
-Most serious adverse reaction is hepatotoxicity
-Tx of many serious systemic fungal infections
What drug is indicated in the treatment of susceptible infections of the skin, hair and nails?
What is the problem with finding a drug useful for viral infections?
It must be able to kill the host and the virus
What are Famciclovir and Valacyclovir?
Prodrugs that are converted to penciclovir and acyclovir as they pass through the intestinal wall