ANTIBIOTICS SEMINAR.pptx department of prosthodotics

ANTIBIOTICS
THEIR USES,PHARMACOKINETICS
AND PHARMACODYNAMICS IN
PROSTHODONTICS
BY- DR. Priya Ashok Asoriya
MDS 1ST
YEAR
DEPARTMENT OF PROSTHODONTICS AND CROWN AND BRIDGE

Contents
 Introduction
 History of Antibiotics
 Classification
 Guidelines for dental practice
 Antibiotic Prophylaxis in Dentistry
 Antibiotics
 Dental Uses
 Pharmacokinetics and Pharmacodynamics of Antibiotics
 Antimicrobials implicated in Prosthodontics
 Conclusion

INTRODUCTION:-
 Antibiotics
Antibiotics are chemical substances used to prevent and treat bacterial
infections by either killing bacteria or by inhibiting their growth.
 Antimicrobial agents
Includes synthetic as well as naturally obtained drugs that attenuate
microorganisms.
 Antimicrobial drugs are the greatest contribution of the 20th century
to therapeutics.
 The purpose of antimicrobial chemotherapy is to aid the host
defences in controlling and eliminating microbes that temporarily
have overwhelmed the protective host mechanisms.
 Waksman defined antibiotic as “a chemical substance produced by
micro-organisms having the property of inhibiting the growth of or
destroying other micro organisms.

HISTORY OF ANTIBIOTICS:-
• 1877 - Louis Pasteur & Robert Koch-First
observed Inhibition of some microbes by
others-Antibiosis.
• 1942 - Waksman renamed it as antibiotic.
• 1908 - Gelmo Synthesized sulfanilamide (1st
sulfonamide)
• 1928 -Alexander Fleming-Penicillin notatum
inhibits growth of bacteria. ‘PENICILLIN’
• 1941 - Chain n Florey Discovered properties
of penicillin

CLASSIFICATION:-
 Based on chemical structure
 Based on mechanism of action
 Based on type of organism against which primarily active
 Based on spectrum of activity
 Based on type of action
 Based on organism susceptible

BASED ON CHEMICAL STRUCTURE
Class Examples Core Structure / Notes
β-lactams
Penicillins, Cephalosporins, Carbapenems,
Monobactams
Contain a β-lactam ring; inhibit cell wall synthesis
Aminoglycosides Streptomycin, Gentamicin, Amikacin Contain amino sugars linked by glycosidic bonds
Tetracyclines Tetracycline, Doxycycline, Minocycline
Four fused rings (tetracyclic core); inhibit protein
synthesis
Macrolides Erythromycin, Azithromycin, Clarithromycin Large lactone ring (14–16 members)
Lincosamides Clindamycin, Lincomycin
Structurally similar to macrolides; inhibit protein
synthesis
Glycopeptides Vancomycin, Teicoplanin Glycosylated cyclic or polycyclic peptides
Polypeptides Bacitracin, Polymyxins
Cyclic or linear peptides; disrupt membranes or
cell walls
Quinolones / Fluoroquinolones Ciprofloxacin, Levofloxacin
Synthetic; contain a quinoline or fluoroquinoline
core; inhibit DNA gyrase
Sulfonamides Sulfamethoxazole, Sulfadiazine
Contain sulfonamide group; inhibit folic acid
synthesis
Oxazolidinones Linezolid Synthetic class; inhibit initiation of protein synthesis
Ansamycins Rifampin
Aromatic ring connected by an aliphatic bridge;
inhibit RNA polymerase
Nitroimidazoles Metronidazole
Contain nitroimidazole ring; effective against
anaerobes

TYPES OF ORGANISM AGAINST WHICH IS
PRIMARILY ACTIVE:-
Antibacterial: Penicillins, Aminoglycosides, Erythromycin
Antifungal: Griseofulvin, Amphotericin B, Ketoconazole
Antiviral: Acyclovir, Amantadine, Zidovudine
Antiprotozoal: Chloroquine, Pyrimethamine, Metronidazole
Antihelminthic: Mebendazole, Praziquantel, diethyl
carbamazine.

CLASSIFICATION BASED ON SPECTRUM
OF ACTIVITY :-
Narrow spectrum: Penicillin G
Streptomycin
Erythromycin
Broad spectrum: Tetracyclines
Chloramphenicol

CLASSIFICATION BASED ON TYPE
OF ACTION:-
Primarily bacteriostatic:-
Sulfonamides, Tetracyclines
Chloramphenicol,Erythromycin, Ethambutol,
Clindamycin
Primarily bactericidal:-
Penicillins , Cephalosporins, Aminoglycosides,
Cotrimoxazole, Vancomycin, Nalidixic acid,
Isoniazid, Ciprofloxacin, Metronidazole.

CLASSIFICATION ACCORDING TO THE ORGANISMS
SUSCEPTIBLE:-
 1. Antibiotics mainly effective against Gm+ve bacteria: for systemic infections:
e.g., Penicillins, Macrolides
 2. Antibiotics mainly effective against Gm-ve bacteria:
e.g., Streptomycin etc
 3. Antibiotics effective against both Gm+ve and Gm-ve bacteria: For systemic
infections: Ampicillin, Amoxicillin, Cephalosporins . For topical use: Neomycin,
Framycetin
 Antibiotics effective against acid fast bacilli : Streptomycin, Rifampin, Kanamycin
 Antibiotic effective against protozoa: Tetracycline
 Antibiotic effective against fungi: Nystatin, Amphotericin B, Griseofulvin,
Fluconazole, Micafungin.
 Antimalignancy antibiotics: Actinomycin D, Mitomycin

PROBLEMS THAT ARISE WITH THE USE OF AMA:-
 Super infection: Appearance of a new infection as a result of antimicrobial therapy
due to destruction of commensal organisms. Commonly associated with the use of
broad spectrum antibiotics e.g. tetracyclines, chloramphenicol, ampicillin etc.
Toxicity: Local irritancy: Gastric irritation, thrombophlebitis.
Hypersensitivity reactions: The whole range of reactions from rash to anaphylactic
shock can occur. More commonly involved are pencillins, cephalosporins, sulfonamides
and fluoroquinolones.
Drug resistance: Production of enzymes that inactivate the drug e.g B lactamase ( B
lactam antibiotics), acetyl transferase (chloramphenicol) kinases and other enzymes
(aminoglycosides)
Alteration of drug binding site
Reduction of drug uptake by the bacterium: Tetracyclines
 Nutritional deficiencies- Prolonged use of AMA may alter the flora which
may result in vitamin deficiency.

ANTIBIOTIC STRATEGIES:-
Cardinal Rules:
 1) Use the right drug.
 2) Use the right dose.
 3) Use the correct dosing schedule.
 4) Correct duration.
 Use a loading dose to rapidly achieve therapeutic blood
levels.
 Avoid combination of bacteriostatic and bactericidal
drugs

CHOICE OF AN ANTIMICROBIAL?
 Patient factors
 Infecting organism
 Drug related
 Patient factors :-
 Age
 Chloramphenicol in new born- grey baby syndrome
 Tetracycline are C/I in children below 6 years
 Half life of aminoglycosides is prolonged in the elderly
 Impaired host defence
 Bactericidal drugs are must in immunocompromised patients

 Pregnancy :-
 All antibiotics pose risk to the fetus when used in
pregnancy.
 Penicillin's, most cephalosporins and macrolides appear
safe.
 The United States Food and Drug Administration (FDA) has
established four levels of drug risk during Pregnancy:
 GROUP A:-Without demonstrated risk to fetus:- No
antibiotic corresponds to group A.
 GROUP B:- Animal reproduction studies have failed to
demonstrate risk to fetus but no adequate studies in
pregnant women:-

 GROUP C:- Animal reproduction studies have shown an
adverse effect on the fetus, no adequate study on pregnant
women
Clarithromycin, the fluorquinolones and the sulfa
drugs
(including dapsone).
 GROUP D:-Teratogenic effects upon the fetus – use of the
drug being conditioned to the obtainment of benefit that
outweighs the risks:-
Tetracyclines and Aminoglycosides.

ORGANISM RELATED
CONSIDERATIONS:-
 Clinical Diagnosis itself directs the choice of the AMA.
 Choice based on bacteriological examination.
 Empirical Therapy:
Refers to initiation of antibiotics depending upon
knowledge and
experience of physician before result of culture and
sensitivity
test is available.
 Broad spectrum antibiotics started in serious infections
like meningitis & septicemia

DRUG RELATED FACTORS:-
Combined Use of Antimicrobial Agents:-
To achieve synergism (supra additive effect)
e.g Penicillin/ampicillin + Streptomycin
/Gentamycin- SABE
To reduce severity of adverse effects
To prevent emergence of resistance
To broaden the spectrum of antimicrobial action

GUIDELINES FOR DENTAL
PRACTICE:-
• Antibiotic therapy should be used as an adjunct to dental
treatment and never used alone as the first line of care.
• Antibiotics are indicated when systemic signs of
involvement are evident, Pain alone or localized Swellings
does not require antibiotic coverage.
• Fevers, malaise, lymphadenopathy or trismus are clinical
signs that possible spread of the infection has occurred. A
rapidly spreading infection or persistent infections require
antibiotic coverage
• Prescriptions written in generic names are as efficacious as
brand names, and produce cost savings.

ANTIBIOTIC PROPHYLAXIS
IN DENTISTRY:-
 Warranted for 2 distinct purposes:
 Prevention of local wound infection
 Prevention of distant infection ( e.g., bacterial
endocarditis) in predisposed patients following dental
procedure.
• Prophylaxis is given in patients with systemic
conditions like rheumatic heart disease, previous
history of endocarditis, heart / orthopaedic
prosthesis.

ANTIBIOTIC CHOICES
 Beta Lactam Antibiotics:-
 Beta Lactam Antibiotics includes-
Penicillin, Cephalosporin, Monobactam, Carbapenem
 All members of this family has a Beta lactam ring and a carboxyl
group resulting in similarities in the pharmacokinetics and
mechanism of action.
 MOA : Inhibits cell wall formation by inhibiting transpeptidase
and cross linking at the cell wall. Peptidoglycan cell wall is
unique to bacteria. No such substance is synthesized in higher
forms- hence penicillin is practically non toxic to man.

Penicillin:-
 First antibiotic to be used clinically in 1941.
 Types:-
 Natural penicillins : Penicillin G and Penicillin V
 Extended-spectrum penicillins : Ampicillin, Amoxycillin
Natural Penicillins :- They are obtained from the fungus Penicillium
chrysogenum
 Penicillin G (Benzyl Penicillin) :-
Pharmacokinetics: Poor oral absorption as it is readily destroyed by gastric acids.
Absorption from I.M. site is rapid and complete and has rapid renal excretion
 Dose: 0.5- 5 MU I.M/I.V , 6-12 hourly.
Available as dry powder, to be dissolved in sterile water at the time of injection.

Adverse effects: Rarely can cause hypersensitivity : Rash , itching, urticaria, &
fever. Anaphylaxis is rare but life threatening.
Penicillin G- Not preferred in dental practice due to fear of causing
anaphylaxis
Penicillin V (Phenoxymethyl penicillin)
Narrow spectrum antibiotic.
Similar to Penicillin G in action but it is resistant to gastric acids and can be
taken
orally.
They are ineffective against Penicillinase producing bacteria like
staphylococci.
T1/2- 90-110 mins.
Dose: 250-500 mg 4 times a day

EXTENDED SPECTRUM PENICILLINS:-
 Ampicillin, Amoxycillin
 Antibacterial spectrum: Broad spectrum covering both gram positive and gram
negative aerobic and anaerobic bacteria commonly causing dental infections.
 Most preferred antibiotic for dental infections.
 Majority of dental cases resolve with 250-500 mg TDS for 5 days.
AMPICILLINS :-
 Active against all organisms sensitive to PnG; in addition, many gram-
negative bacilli
 Pharmacokinetics:-
 Acid resistant
 Oral absorption is incomplete but adequate
 Primary excretion is kidney, partly enterohepatic circulation occurs
 Plasma half life is 1hr

 Medical Uses:- UTI, RTI, Meningitis, Gonorrhoea, typhoid fever,
bacillary dysentery, Subacute bacterial endocarditis and Septicemias
Adverse effects:-
• Diarrhoea(it is incompletely absorbed –the unabsorbed drug irritates the
lower intestine as well as causes marked alteration of bacterial flora)
• Rashes
• Hypersensitivity
Interactions:-
• Hydrocortisone –inactivates ampicillin if mixed in the I.V solution
• Oral contraceptive –failure of oral contraception
• Probenecid–retards renal excretion
DOSE :-Adult- 0.5-2g oral/i.m/i.v depending on severity of infection ,every
6 hr
• Child-50-100 mg/kg given in equally divided doses every 6 hr
• Maximum-2-4 g/ day

AMOXICILLIN:-
 Close congener of ampicillin
 Similar in all respects except :–
 Oral absorption is better
 Food doesn’t interfere with absorption
 Higher and more sustained blood levels are produced
 Incidence of diarrheoa is lower due to complete
absorption in the GI tract.
Uses:-
Most frequently used in dental infections 250-500mg for
5 days TDS.
Prophylaxis for local and distant infection

CEPHALOSPORINS:-
 Mechanism of action:
All cephalosporins have the same mechanism of action as penicillin, i.e.
inhibition of
bacterial cell wall synthesis
Spectrum of Activity: Bactericidal
 CLASSIFICATION:-

DENTAL USES:-
Alternative to penicillin/amoxicillin (if pt develop
resistance/allergy), orally active 1st and 2nd gen drugs are
used in orodental infections.
1st gen- cephalexin,cephadroxil used due to high activity
against gram +ve bacteria and good penetration in alveolar
bone(socket).
2nd gen -cefuroxime,axetil and cefaclor are the only ones
which have good activity against oral anaerobes and
preferred in dentistry, eg: klebsiella which may occur in
neutropenic patients.
Cephalexin and cephadroxil are alternatives to amoxicillin for
prophylaxis of local wound infection as well as bacterial
endocarditis following dental surgery in predisposed patients.

TOPICAL ANTIBIOTICS:-
 Atridox:(doxycycline hyclate):- Available as a tray
or pouch containing a doxycycline hyclate syringe (50 mg).
• Used in the treatment of chronic adult periodontitis for a
gain in clinical attachment, reduction in probing depth, and
reduction in bleeding on probing.
 ARESTIN :-
ARESTIN (minocycline HCl) Microspheres, 1 mg is a
concentrated, locally applied antibiotic that remains active in
the pocket for an extended period of time to reduce pocket
depth.
 PerioChip :- Its a Orange-brown, rectangular chip
(rounded at one end) for insertion into periodontal pockets
as a part of maintenance therapy
• Contains 2.5 mg of chlorhexidine gluconate
 Others: Actisite Elyzol

Pharmacokinetics of Antibiotics
 Pharmacokinetics in antibiotics refers to how the body absorbs, distributes,
metabolizes, and excretes these drugs. Understanding pharmacokinetics is
essential for determining dosing, frequency, and route of administration to
achieve optimal therapeutic levels while minimizing toxicity and resistance.
1.Absorption:
 Most antibiotics used in prosthodontics (e.g., amoxicillin, clindamycin) are
administered orally or intravenously.
 Oral bioavailability is crucial for effective prophylaxis or treatment.
2.Distribution :
 Antibiotics must reach therapeutic levels in oral tissues, alveolar bone, and
gingiva, especially in implantology or post-surgical care.
 Lipid solubility and protein binding affect tissue penetration.

3.Metabolism:
 Many antibiotics undergo hepatic metabolism.
 For instance, ‘clindamycin’ is extensively metabolized in the liver.
 Metabolism affects half-life and dosing intervals.
4. Elimination:
 Primarily via kidneys (e.g., penicillins) or liver (e.g., macrolides).
 Impaired renal/hepatic function necessitates dose adjustments

Pharmacodynamics of Antibiotics
 Pharmacodynamics refers to the biological effects of antibiotics on microorganisms, including
the mechanism of action, spectrum of activity, and time/concentration dependency.
1. Mechanism of Action:
 Bactericidal drugs (e.g., beta-lactams): kill bacteria by disrupting cell wall synthesis.
 Bacteriostatic drugs (e.g., clindamycin): inhibit protein synthesis, preventing bacterial growth.
2. Spectrum of Activity:
 Prosthodontic infections usually involve Gram-positive cocci and anaerobes.
 Amoxicillin is effective against many oral pathogens; clindamycin is used in penicillin-allergic
patients.
3. Time-Dependent vs. Concentration-Dependent Killing
 Time-dependent (e.g., beta-lactams): efficacy depends on the time the drug concentration
remains above the MIC (Minimum Inhibitory Concentration).
 Concentration-dependent (e.g., aminoglycosides) : efficacy depends on peak concentration.

ANTIMICROBIALS IMPLICATED IN
PROSTHODONTICS:-
Candida associated denture stomatitis
 antifungal drugs play a major role in treatment
of Candida albicans which causes oral moniliasis (thrush)
and can also infect prosthetic devices.
 Local therapy with nystatin, amphotericin B, miconazole,
or clotrimazole should be preferred to systemic therapy
with ketoconazole or fluconazole because resistance
of Candida species occurs with them regularly.
 Treatment should continue for a minimum of 4 weeks
along with meticulous oral hygiene maintenance.

 The most common drug used in dentistry to treat fungal infections of
the oral cavity is NYSTATIN.
 Nystatin has a dose-dependent fungistatic or fungicidal effect on
several fungi, including C. albicans. Because nystatin is not absorbed,
tablets are usually held in the mouth for several minutes until they
dissolve.
 Colonized dentures can be treated by soaking them in a solution of
nystatin.
 Clotrimazole, a fungistatic, is also an effective treatment for infections
caused by C. albicans.
 A 10 mg troche is dissolved in the mouth five times a day for 14 days.
Clotrimazole is not absorbed and causes minimal side effects.

Traumatic ulcers :-
May be caused in the denture wearers due
to friction between the tissue surface of the
denture and mucosa.
Primary line of treatment includes
discontinuation in wearing dentures and
application of topical benzoczine 20% and
benzakonium hexachloride, available as
mucopain or dologel (also contains
salicylates for antibacterial action).
In cases of severe inflammation, kenacort
gel (containing triamcinolone acetonide
0.1%) is indicated.

IMPLANT PROSTHESIS:-
 The implant therapy is usually a two-stage procedure which involves the surgical and a
prosthetic phase, and the success of the therapy involves the prevention of the infection
in and around the implants.
 SURGICAL PHASE-
 The antibiotic coverage is essential during the placement of the implant whether it is
an immediate-loaded or a delayed loading implant
 The prophylactic measures are-Standard regimen: Amoxicillin 3.0 g orally 1 h before
procedure; then 1.5 g 6 h after the initial dose.
 Patients allergic to amoxicillin/penicillin: Erythromycin ethyl succinate 800 mg or
erythromycin stearate 1.0 g orally 2 h before the procedure; then half the dose 6 h after
the initial dose.
 Clindamycin 300 mg orally 1 h before the procedure and 150 mg 6 h after the initial
dose

 The most commonly used antibiotics for
prophylactic regimens are used with the lower
dosage levels. The patients are usually given
amoxicillin and dicloxacillin combination or
amoxicillin with clavulanic acid combination
before the start of the therapy which is to be
continued for three days
 Maintenance phase
 The patients are advised with the mouthwash in
order to properly maintain the implants.
Chlorhexidine digluconate, at concentrations of
0.12%, has been approved for the treatment of
gingivitis and suppression of the formation of
plaque. Chlorhexidine-containing mouth rinses are
useful adjuncts that may facilitate healing after
insertion of the implant dentures.

Prophylactic Use
 Indicated in immunocompromised patients, or those at risk of infective
endocarditis.

CONCLUSION:-
 Antibiotics play an important role in improving the response of the patient
in both pre-treatment and post-treatment phases. Drugs in dentistry act as a
primary treatment modality as well as facilitator of dental procedures. With
phenomenal growth of information on the mechanism of action and clinical
application of antibiotics as well as rapid introduction of new drugs,
pharmacology has become increasingly important to all dentists.
 Success or failure of a clinical procedure often hinges on the proper
application of pharmacologic principles of locally acting drugs. The
competent and successful practitioner must therefore have a good
background in basic pharmacology, be knowledgeable of
pharmacotherapeutics, and keep abreast of the latest advances in medicinal
agents.

ANTIBIOTICS SEMINAR.pptx department of prosthodotics

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