Pharmacology for Dentistry

334 Section 9/ Chemotherapy

pseudomembranous colitis, dizziness, rash,
headache, pruritus, jaundice, leucopenia etc.

It is indicated in upper and lower respi-
ratory tract infections, skin infections, septi-
caemia, bone and joint infection including
acute haematogenous osteomyelitis.

VANCOMYCIN

It is a glycopeptide antibiotic and
primarily active against gram positive
bacteria, strains of Staph. aureus which are
resistant to methicillin are inhibited by
vancomycin. It is also effective against
Strep. viridans, enterococcus, Clostridium
difficile and diphtheroids.

It is bactericidal drug and it exerts it
action by inhibiting the synthesis of the
cell wall in sensitive bacteria.

After oral administration it is poorly
absorbed. It is given by parenteral route
and high concentration of drug may
accumulate when renal function is
impaired.

It is indicated in serious life threatening
staphylococcal infections resistant to other
antibiotics, in severe staphylococcal
infections in patients who are allergic to
penicillin and cephalosporin.

Adverse effects include skin rash, ana-
phylaxis, nephrotoxicity, ototoxicity like
other aminoglycosides. Other side effects are
local pain and phlebitis at the site of injec-
tion, fever, eosinophilia and hypotension.

POLYPEPTIDE ANTIBIOTICS

They have bactericidal activity against

gram negative bacteria only and are low

molecular cationic polypeptide antibiotics.

They are listed in table 9.5.2.

POLYMYXIN B

Has detergent like action on cell

membrane and have high affinity for

phospholipids. They penetrate into and

disrupt the structure of cell membranes,

as a result of which amino acids and ions

leak out.

After oral administration negligible or

no absorption occurs.

It is used systemically in enteric

infections caused by gram negative

organisms and topically for pseudomonal

infections of conjunctiva and cornea, burns

and skin.

Adverse effects include nausea, vom-

iting, diarrhoea after oral administration.

Parenteral administration (IM) cause pain,

flushing, ototoxicity, nephrotoxicity and

neurotoxicity.

COLISTIN

Also known as polymyxin E, is also a

cationic detergent used only orally. Side

effects and uses are similar to polymyxin B.

Table 9.5.2: Classification of polypeptide antibiotics.

Polymyxin B (AEROSPORIN) 15,000-25,000 U/kg daily for 7-10 days

Colistin (as sulphate) (WALAMYCIN) 25-100 mg TDS

Bacitracin 250 μ/g powder, skin/eye ointment

Tyrothricin (0.5 mg/kg skin cream, 0.2 mg/ml solution (topical), 0.05% as

otic solution with benzocaine