Glycopeptides & Other Cell Wall Synthesis Inhibitors

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Questions and Answers

What is the primary cause of the 'red man' or red neck syndrome associated with telavancin?

Allergic reaction to the drug

Direct irritation of blood vessels

Release of histamine from mast cells (correct)

Release of serotonin from platelets

Which drug interaction increases the likelihood of 'red man' syndrome during telavancin administration?

Antibiotics

Opioids (correct)

Non-steroidal anti-inflammatory drugs (NSAIDs)

Anticoagulants

What is a recommended strategy to prevent 'red man' syndrome when administering telavancin?

Prolonging the infusion period (correct)

Administering in a larger vein

Increasing the dosage

Using a higher concentration solution

What type of bacteria is telavancin primarily effective against?

Gram-positive bacteria (A) Signup and view all the answers

How does telavancin differ from vancomycin in terms of susceptibility?

It has reduced susceptibility to certain strains (D) Signup and view all the answers

What is the recommended formulation for susceptibility testing to minimize false positive results?

Growth medium with Glucose-6-phosphate (C) Signup and view all the answers

What is the approximate oral bioavailability of Fosfomycin?

40% (A) Signup and view all the answers

What are the peak serum concentrations of Fosfomycin after a 4-gram oral dose?

30 mcg/mL (A) Signup and view all the answers

For what condition is Fosfomycin approved as a single 3-gram dose treatment?

Uncomplicated lower urinary tract infections (C) Signup and view all the answers

What is the approximate half-life of Fosfomycin?

4 hours (D) Signup and view all the answers

What condition can develop after rapid IV infusion of glycopeptides?

Red man syndrome (A) Signup and view all the answers

What should be maintained to minimize the risk of ototoxicity with vancomycin?

Serum concentrations below 60 mcg/mL (C) Signup and view all the answers

Increased risk of ototoxicity is associated with which patient demographic?

Patients older than 53 with hearing problems (D) Signup and view all the answers

Which of the following organisms is vancomycin effective against?

MRSA (B) Signup and view all the answers

What can result from using impure preparations of glycopeptides?

Nephrotoxicity (C) Signup and view all the answers

Which bacteria are known to exhibit intermediate or resistant levels to vancomycin?

VISA and VRSA (C) Signup and view all the answers

What is an important consideration in the use of vancomycin against Enterococcus faecium and faecalis?

High levels of aminoglycoside resistance (D) Signup and view all the answers

Which of the following is NOT a risk factor for developing ototoxicity with vancomycin?

Low body weight (A) Signup and view all the answers

What notable adverse effect is associated with Vancomycin?

Nephrotoxicity (D) Signup and view all the answers

Which drug interaction could lead to decreased excretion rates when used with Telavancin?

Cisplatin (B) Signup and view all the answers

Which of the following drugs may cause Red Man syndrome when administered?

Telavancin (A) Signup and view all the answers

What effect may occur from the combination of Telavancin and Amitriptyline?

Prolonged QTc interval (D) Signup and view all the answers

Which adverse effect is associated with Teicoplanin?

Fever (C) Signup and view all the answers

What is a potential result of using NSAIDs concurrently with Dalbavancin?

Enhanced nephrotoxicity (B) Signup and view all the answers

What is the significant concern with the co-administration of aminoglycosides and Vancomycin?

Increased ototoxicity (D) Signup and view all the answers

What adverse effect can be caused by Telavancin?

Flushing (C) Signup and view all the answers

Which adverse effect is least likely to be caused by Dalbavancin?

Ototoxicity (D) Signup and view all the answers

Which of the following is a notable interaction between Teicoplanin and methicillin-resistant bacteria?

Synergy with beta-lactams (C) Signup and view all the answers

What is the recommended dosage for treating tuberculosis?

0.5-1g per day in two or three divided doses (D) Signup and view all the answers

Which of the following adverse reactions is associated with Cycloserine?

Severe dose-related CNS toxicity (D) Signup and view all the answers

What can exacerbate the CNS effects caused by Cycloserine?

Benzodiazepines and other CNS depressants (A) Signup and view all the answers

How is most of the drug excreted from the body?

In active form in the urine (B) Signup and view all the answers

What should be noted about maintaining oral dosages of Cycloserine?

They should not exceed 0.75g/day to avoid CNS effects. (D) Signup and view all the answers

Bacitracin is often indicated for which of the following conditions?

Suppression of mixed bacterial flora in surface lesions (D) Signup and view all the answers

What type of solutions can Bacitracin be used for irrigation?

Solutions containing 100-200 units/mL in saline (B) Signup and view all the answers

What is the concentration range for Bacitracin solutions used for irrigation?

100-200 units/mL (B) Signup and view all the answers

Study Notes

Ototoxicity and Risk Management

Ototoxicity rates are lower than those observed with penicillins, both in vitro and in vivo.
To minimize ototoxicity, maintain peak serum concentrations of vancomycin below 60 mcg/mL.
Increased ototoxicity risk in patients over 53 with preexisting hearing problems or renal impairment.

Adverse Reactions of Glycopeptides

"Red Man" Syndrome: Rapid IV infusion (4 to 10 mins) can cause histamine release leading to flushing and erythema.
Prevention includes extending the infusion time to 1-2 hours and using H1 antihistamines beforehand.
Ototoxicity is irreversible and is a significant concern, especially in impure preparations.
Nephrotoxicity is also associated with these medications.

Spectrum of Antibacterial Activity

Glycopeptides target Gram-positive bacteria, including:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Vancomycin-intermediate (VISA) and Vancomycin-resistant Staphylococcus aureus (VRSA)
- Vancomycin-resistant Enterococci (VRE)

Telavancin

A semi-synthetic lipoglycopeptide derived from vancomycin.
Effective against Gram-positive bacteria and shows reduced susceptibility to vancomycin in some strains.

Teicoplanin

A glycopeptide antibiotic similar to vancomycin, administered via IM or IV.
Susceptibility tests should use glucose-6-phosphate to avoid false positives.

Pharmacokinetics of Fosfomycin

Available in oral and parenteral forms with an oral bioavailability of ~40%.
Peak serum concentrations reach 10 mcg/mL and 30 mcg/mL after 2-gram or 4-gram doses, respectively.
Significant urinary concentrations are achieved, exceeding MICs for most urinary pathogens.
Administered as a single 3-gram dose for uncomplicated lower urinary tract infections in women.

Bacitracin

An antibiotic produced by Streptomyces orchidaceous, available as an ointment (500 units/g), often combined with Polymyxin or Neomycin.
Effective for suppressing mixed bacterial flora in skin lesions and wounds.
Solutions containing 100–200 units/mL can be used for joint or wound irrigation.

Cycloserine Characteristics

Used for treating tuberculosis; 0.5-1g dosages in divided doses.
Can cause serious CNS toxicity, including headaches, tremors, and acute psychosis.
Lower dosages below 0.75 g/day typically reduce adverse effects.

Notable Drug-Drug Interactions

Concurrent use of vancomycin with aminoglycosides increases risks of ototoxicity and nephrotoxicity.
Teicoplanin shows synergy with beta-lactams against resistant Staphylococcus.
Telavancin reduces excretion rates of cisplatin; it can also prolong QTc interval when combined with amiodarone or amitriptyline.

Summary of Notable Adverse Effects

Vancomycin: Red Man syndrome, ototoxicity, nephrotoxicity, fever, pain, skin reactions.
Teicoplanin: May cause Red Man syndrome and has similar effects as vancomycin.
Telavancin: Risk of nausea, taste disturbances, insomnia, and QTc prolongation.
Dalbavancin: May cause renal function reduction when used with NSAIDs and diuretics.

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Description

This quiz explores the ototoxicity associated with glycopeptides, including risk management and adverse reactions. It highlights the mechanisms of ototoxicity, particularly in patients with preexisting conditions, and details the spectrum of antibacterial activity of glycopeptides against Gram-positive bacteria. Test your knowledge on these important pharmacological concepts.