mbbs broad spectrum amas, macrolides and misc. amas class ii

8/12/2019 MBBS Broad spectrum AMAs, Macrolides and Misc. AMAs Class II

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1. Broad spectrum AMAs

2. Macrolides

3. Misc. AMAs

Class II

Dr.U.P.RathnakarMD.DIH.PGDHM

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Protein synthesis inhibitors

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1. Broad spectrum AMAsTetracyclines

Chloramphenicol

2. Macrolides

3. Misc. AMAs

Clindamycin,

Streptogramins,

Linezolid

Vancomycin{Cell wall[-]}

Topical agents [Varied MOA]

Mupirocin

Fusidic acid

Polymyxin B, Colistin, Bacitracin, Tyrothricin

Aminogycosides


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Identify broad spectrum pair

A. Clindamycin & Erythromycin

B. Tetracycline & clindamycin

C. Chloramphenicol & vancomycinD. Tetracycline & Chloramphenicol

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Protein synthesis inhibitor does not include

A. Chloramphenicol

B. Vancomycin

C. AminoglycosideD. Oxytetracycline

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Drug which prevents binding of tRNA to

30s ribosome at A site is-

A. Doxycycline

B. Aminoglycoside

C. ChloramphenicolD. Clindamycin

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Anti ADH tetracycline is-

A. Doxycycline

B. Tetracycline

C. DemeclocyclineD. Oxytetracycline

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Highly lipid soluble TC is-

A. Doxycycline

B. Tetracycline

C. DemeclocyclineD. Minocycline

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TC administered once a day is-

A. Tetracycline

B. Oxytetracycline

C. Demeclocycline

D. Doxycycline

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TC which causes vestibulartoxicity is-

A. Minocycline

B. Tetracycline

C. DoxycyclineD. Demeclocycline

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MOA of chloramphenicol is-

A. Inhibit binding at A site

B. Inhibit amino acid transfer

C. Inhibit translocation

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TC which is safer in renal

impairment is-A. Doxycycline

B. DemeclocyclineC. Tetracycline

D. Oxytetracycline

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Gray baby syndrome is caused by

A. Chloramphenicol

B. DemeclocyclineC. Tetracycline

D. Oxytetracycline

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TCs are contraindicated in-

A. Pregnancy

B. LactationC. Children

D. All of the above

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Macrolides

With a macrocyclic lactone ring withattached sugars

Erythromycin

Roxithromycin,

Clarithromycin and

Azithromycin

Spiramycin [To prevent trans placental transmission of toxoplasmosis]

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9

AG

EP A

mRNA

tRNAW

MacrolidesErythromycin, Azithro, Clarithro, Roxithromycin]


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Bacteriostaticcidal [higherconcn]

Enters by active transport It combines with 50Sribosome

subunit and interferes with

translocation.

8

Macrolides [Erythromycin-prototype]

MOA


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Erythromycin

Bacterial resistance Less permeable to erythromycin

Acquire the capacity to pump it out.

Enterobacteriaceae have been found to produce

an erythromycin esterase. Alteration in the ribosomal binding site for

erythromycin

Cross resistance with clindamycin andchloramphenicol -binding sites for all these arenext to each other.

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Erythromycin-spectrum

S.Pyogenes, S.pneumoniae,

n.gonnorrhoeae, clostridia, C.diphtheria,

listeria- Erythromycin and penicillin

Campylobacter, mycoplasma, pertusis,

chlamydia, N.meningitidis- E.mycin

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Erythromycin

PK Erythromycin base is acid labile. - enteric coated tablets,

Food delays absorption

Does not cross BBB-crosses placenta

Partly metabolized and excreted primarily in bile in the

active form.

Renal excretion is minor;

Dose need not be altered in renal failure.

Enzyme inhibitor CYP3A4 Erythromycin stimulates motilin receptors in the g i t -

thereby induces gastic contractions, hastens gastric

emptying and promotes intestinal motility [used

postoperatively to promote peristalsis]5


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Erythromycin

ADEs & DIs GIT

Hypersensitivity [Skin and hepatic]

Chlolestatic jaundice [E.estolate-acid stable]

DIs [Erythro and Clarithro]

Enzyme inhibitor [ toxicity of theophylline,

carbamazepine, valproate, warfarin, digoxin etc

VT with cisapride, astemizole, terfenadine Ototoxicity in high doses

Pregnancy- E.mycin safe [Others may not be]

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Erythromycin uses

3

First choice

1. Mycoplasma pneumonia

2. Whooping cough

3. Chancroid

Alternative to penicillin

1. Str. Pharyngitis [Rh.fever]

2. Diphtheria, Tetanus

3. Syphilis

4. Leptospirosis

Non-infective uses

1. Antiinflammatory-rarely used-decreases cytokines

2. Improve post op. gastric emptying

E th R i Cl i A ith


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Erythro Roxi Clari AzithroSource Natural Semisynth Semisynth Semisynth

Efficacy + ++ ++ ++Durationof action

6h 12 Long Long

Oral Enteric

coated

Stable Stable Stable[Food does not

interfere]

Dosage 500mgQID 150BD 250BD 500 OD

DI yes No Yes No

Spectrum

& Uses

M.Pneumonia

LeginnairesChlamydiaPertusisTetanusStrepto

Staphylo

As

erythro

As erythro +

MACLeprosyH.Pylori[triple drug]

As erythro +

MACLGVH.InfluenzaSalmonella

MalariaToxo lasmosis2


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Advantages of azithromycin

over E.mycin Acid stable

Single dose/day

Wider spectrum No drug interactions

Disadvantage-should not be administeredin pregnancy

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KETOLIDES

Telithromycin & Cethromycin

Ketolides are semisynthetic14-membered-ring macrolides

Macrolide-resistant strains are susceptible to ketolides because

- structural modification renders them poor substrates for efflux

pump-mediated resistance and they bind to ribosomes of some

bacterial species with higher affinity than macrolides

Inhibitor of the CYP3A4 enzyme system and may slightlyprolong the QTc

HEPATOTOXIC [restricted use]

Visual disturbances

CI in myasthenia gravis 1

mbbs broad spectrum amas, macrolides and misc. amas class ii

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