NTA Level 5 • Semester 1 • PST05104

Pharmacodynamics of Fluoroquinolones

Pharmacology and Therapeutics • Source Session/Topic 22

Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability.

Session 22: Pharmacodynamics of Fluoroquinolones

Total Session Time: 120 minutes

Prerequisites

None

Learning Tasks

By the end of this session students are expected to be able to:

Describe mechanism of action of Fluoroquinolones

Describe drug interactions associated with Fluoroquinolones

Describe side effects of Fluoroquinolones

Describe contraindications of Fluoroquinolones

Resources Needed:

Flip charts, marker pens, and masking tape

Black/white board and chalk/whiteboard markers

Computer and LCD projector

SESSION OVERVIEW

Step

Time

Activity/

Content

Step

Time

Activity/

Content

Step

Time

Method

Content

Method

Presentation

Introduction, Learning Tasks

minutes

Presentation

Introduction, Learning Tasks

minutes

Presentation/

Mechanism of Action of Fluoroquinolones

minutes

Buzzing

Mechanism of Action of Fluoroquinolones

minutes

Buzzing

Presentation/

Drug Interactions Associated With

minutes

brainstorming

Fluoroquinolones

minutes

brainstorming

Fluoroquinolones

Presentation

Side Effects of Fluoroquinolones

minutes

Presentation

Side Effects of Fluoroquinolones

minutes

Presentation/

Contraindications of Fluoroquinolones

minutes

Brainstorming

Contraindications of Fluoroquinolones

minutes

Brainstorming

PST 05104 Pharmacology & Therapeutics

176

NTA Level 5 Semester 1 Facilitator Guide

Presentation

Key Points

minutes

Presentation

Key Points

minutes

Presentation

Evaluation

minutes

Presentation

Evaluation

minutes

PST 05104 Pharmacology & Therapeutics 177 NTA Level 5 Semester 1 Facilitator Guide

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing.

STEP 2: Mechanism of Action of Fluoroquinolones (45 minutes)

Activity: Buzzing (5 minutes)

ASK students to pair up and buzz on the following question for 2 minutes

How do Fluoroquinolones produce their pharmacological effects?

ALLOW few pairs to respond and let other pairs add on points not mentioned

WRITE their response on the flip chart/board

CLARIFY and SUMMARIZE by using the content below

Fluoroquinolones

DNA is normally supercoiled. Supercoiled DNA is under too much tension to be separated, so an extra step is required before replication and transcription can occur. DNA gyrase relaxes supercoiled DNA by cutting it, allowing rotation to occur, and then reattaching it.

Fluoroquinolones bind to and inhibit DNA gyrase (also called topoisomerase II) and topoisomerase IV. Fluoroquinolones inhibit DNA gyrase in gram-negative organisms and topoisomerase IV in gram-positive organisms.

The fluoroquinolones inhibit DNA gyrase after the cutting step, preventing reattachment from occurring.

o At high doses this leads to the release of these broken segments of DNA.

o It is thought that the accumulation of these DNA fragments leads to cell death, accounting for the bactericidal action of fluoroquinolones.

Fluoroquinolones can enter human cells easily and therefore are often used to treat intracellular pathogens.

Originally, quinolones were mainly effective against gram-negative bacteria, but newer agents are useful against gram-positive cocci as well.

Mechanism of resistance:

o Mutations in the genes that encode type II topoisomerase result in the enzyme not being inhibited by the fluoroquinolone.

PST 05104 Pharmacology & Therapeutics 178 NTA Level 5 Semester 1 Facilitator Guide

Alterations in membrane porins or efflux pumps that actively pump the drug out of the bacterial cell result in lower drug levels inside the bacteria.

STEP 3: Drug Interactions Associated with Fluoroquinolones (20 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

What are drug interactions associated with fluoroquinolones drugs?

ALLOW few students to respond

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

The following are drug interaction associated with Fluoroquinolones;

With NSAIDS, fluoroquinolones may potentiate CNS toxicity and cause seizures.

With theophylline, they will increase theophylline levels and increase risk of theophylline toxicity.

STEP 4: Side Effects of Fluoroquinolones (20 minutes)

Fluoroquinolones have the following side effects:

Most fluoroquinolones are cleared renally, and dose adjustment may be required in patients with renal impairment.

Tendon ruptures (Achilles, shoulder); occur rarely. The mechanism of this complication is not well understood.

Gatifloxacin: hyperglycemia

Trovafloxacin: acute liver failure and death

Temafloxacin: hemolytic anemia

Grepafloxacin: long QT syndrome and sudden death

Fleroxacin: phototoxicity

PST 05104 Pharmacology & Therapeutics 179 NTA Level 5 Semester 1 Facilitator Guide

STEP 5: Contraindications of Fluoroquinolones (20 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

What are the contraindications of Fluoroquinolones? ALLOW few students to respond?

WRITE their responses on the flip chart/ board CLARIFY and SUMMARISE by using the content below

Fluoroquinolones have the following contraindications:

Moxifloxacin: is cleared by the liver and therefore contraindicated in patients with hepatic failure.

Pregnancy

Children: Joint pain (arthralgia) and swelling has occurred, and therefore administration to children is not common.

STEP 6: Key Points (5 minutes)

More than 30 different fluoroquinolones exist. Some are used for veterinary purposes only.

Newer fluoroquinolones have extended spectrum against gram-positive cocci as well.

Fluoroquinolones have some significant drug interactions

STEP 7: Evaluation (5 minutes)

What is the mechanism of action of fluoroquinolones?

What are contraindications of ciprofloxacin?

What are the side effects of gatifloxacin?

PST 05104 Pharmacology & Therapeutics 180 NTA Level 5 Semester 1 Facilitator Guide

References

Katzung, B. G. (2018). Basic and clinical pharmacology. New York: Mcgraw Hill Education.

Santos, R. R., Rang, H. P., Dale, M. M., Ritter, J. M., & Flower, R. J. (2007). Rang & Dale Farmacologia. Rio de Janeiro: Elsevier.

Tripathi, K. (2018). Essentials of Medical Pharmacology. Place of publication not identified:

Jaypee Brothers Medical P.

Ministry of Health and Social Welfare. (2013). Standard Treatment Guidelines & National Essential Medicines List Tanzania Mainland (4th ed.). Dar es salaam, Tanzania government printers.

Robert L. Talbert, Gary C. Yee, Gary R. Matzke, Barbara G. Wells, L. Michael. (2014). Pharmacotherapy: A Pathophysiologic Approach (9th ed.). New York, McGraw-Hill Education.

Sally S.R, Jeanne C.S. (2000). Introductory Clinical Pharmacology (6th ed) New York, Lippincott Williams and Wilkins.

School of Pharmaceutical sciences. (2011).Tanzania Pharmaceutical Handbook (2nd ed.).

Dar es Salaam, ARDHI University press.

The Royal Pharmaceutical Society of Great Britain. (2007). Martindale, the Extra Pharmacopoeia (5TH ed). London, pharmaceutical press.

The Royal Pharmaceutical Society of Great Britain. 2009. British National Formulary (59th ed). London, BMJ Group and RPS Publishing.

PST 05104 Pharmacology & Therapeutics 181 NTA Level 5 Semester 1 Facilitator Guide

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