- Metronidazole is commonly used antibiotic in periodontal therapy that is effective against anaerobic bacteria. It can attain effective concentrations in gingival tissues, saliva, and crevicular fluid. - Systemic antibiotic therapy with metronidazole should be reserved for acute periodontal infections, as an adjunct to periodontal treatment, or for patients who continue experiencing periodontal breakdown despite treatment. - When using metronidazole, it is recommended to not use it as a monotherapy but combine it with other antibiotics like amoxicillin or ciprofloxacin. Common dosing regimens include 250mg of metronidazole three times daily combined

2. Systemic Metronidazole i n
Periodontal Therapy
Usama M. madany
Professor, Department of Oral Medicine
Periodontology, Diagnosis and Oral Radiology,
Faculty of Dental Medicine , Al-Azhar University

3. - Commonly used antibiotics in periodontal therapy :
Tetrayclines (doxycycline) Metronidazole
Clindamycin Penicillins (amoxicillin)
Erythromycins (azithromycin, clarithromycin)
Ciprofloxacin
The microbial etiology of inflammatory periodontal
diseases provides the rationale for the local and
systemic use of different antibiotics in periodontal
therapy.

4. -Systemic antibiotic therapy in periodontics should be
reserved to the following:
A. Prophylaxis for patients with medical problems requiring
antibiotic coverage.
B. Patients with systemic manifestations associated with
acute periodontal infections (ANUG and acute periodontal
abscess) .
C. As an adjunct to surgical and non surgical periodontal
therapy.
D. Patients who undergo continued periodontal breakdown in
spite of thorough debridement and excellent home care .

5. Metronidazole
Pharmacology and spectrum:
-It is a nitroimidazole compound mainly active against
protozoal infections.
-It is very effective in low reduction potential areas, and
bactericidal to anaerobes through inhibition of DNA
synthesis.
-It can readily attain effective antibacterial concentration in
gingival tissue, saliva and crevicular fluid.
-It is effective against the microorganism strongly
associated with and implicated in pathogenesis of
periodontal disease.

6. % Absorption after Peak serum level Serum half-life
Antibiotic oral adminestration (µg/ml) (hours)
Metronidazole 90 20-25 6-14
Tetracyclines 93 2- 4 18
(Doxycyline)
Clindamycin 90 5 2.4
Penicillins 75 5- 8 1.2
(Amoxicillin)
Ciprofloxacine 70 1.5 4
Erythromycines 37-50 0.4-3 5-12
Selected pharmacological features of common antibiotics in use
for periodontics

7. •metronidazole
metronidazole
metronidazole
Aa
P. intermedia
sprichetes
Anaerobes

8. Metronidazole
Spirochetes
P. gingivalis
P. intermedia
A.actinomycetemcomitans
Hydroxy metaolites
of nitroimidazole
+other antibiotics
tissues

9. Clinical use of systemic metronidazole:
If to be used, metronidazole should not be administered as monotherapy.
Alone
1- Treatment of ANUG 2- Treatment of periodontitis
250-500 mg/ tid/ 3-5 days 750-1000 mg /day for 7-14 days*
- growth of anaerobic bacteria.
- histopathological and Clinical
signs of periodontitis.
- the need for surgery.
-Recommended doses :
250 mg/ tid/ 7 days (Greenstien, 1993).
500 mg/ tid/ 8 days (Slots and Ting,
2002)
Loesche 1992; Nieminen et al.1996; Soder 1999.

10. Combined with other antibiotics
-Complexity of periodontal pathogens in dental biofilm
(dental plaque).
-Considerable variation of sensitivity of these bacteria to
different antibiotics.
Treatment of periodontitis:
1- Metronidazole + amoxiciilin 250 mg/ tid/ 8 days of each
drug.
2- Metronidazole 250 mg + amoxycillin-clavulanate
potassium (augmentin) 375 mg / tid/ 8 days.
3- Metronidazole + ciprofloxacin 500 mg/ bid/ 8 days of
each drug.
-These regimens resulted in improved clinical status and suppression
and/or elimination of Aa and Pg in aggressive and recurrent forms of
periodontitis ( Slots and Ting 2002, AAP position paper 2004).

11. Adsverse reactios and side effects:
-Nausia/vomiting
-Unpleasant (metallic) taste.
-Pregnancy: Possible risk of teratogenicity.
Drug Interactions*:
1-Metronidazole metabolism of warfarin prolonged
prothrombin time bleeding tendency (definite action).
2-Metronidazole + Ethanol disulfiram-like reaction:
nausia, vomiting, severe cramps, flushing, sweating,
hypotension, palpitation and headache (probable action).
*Yagiela, 1999, Horn et al.2004

12. 3-Metronidazole metabolism of oral hypoglycemic drugs
Hypoglycemia (probable) .
5-Metronidazole may inhibit the action of estrogen
components of oral contraceptives unexpected
pregnancies ( Hersh 1999).
6-Barbiturates effectiveness of metronidazole (probable).
Precautions on prescription
1-Metronidazole should be avoided in patients undergoing
warfarin therapy.
2-Alcohol containing products should be avoided during
metronidazole therapy and for at least one day after therapy
is discontinued.

13. 3-Metronidazole is better to be avoided for diabetics on
oral hypoglycemic drug.
4-It should be avoided during pregnancy especially in the
first trimester, and also for females on oral contraceptives.
5-In patients with impairment of liver functions,
metronidazole is better to be avoided or its dose to be
decreased.
6-Dose for children should by properly adjusted according
to body weight (7.5 mg/kg 8 hourly).