Vancomycin

Introduction Overview

Generic Name

vancomycin

Brand Name

FIRST-Vancomycin 25
FIRST-Vancomycin 50
Firvanq
Vancocin
Vancocin HCl
Vancocin HCl Pulvules

Dosage Form

oral capsule
oral solution (liquid/oral suspension)

Drug Class

Glycopeptide antibiotics

Pharmacokinetics

Absorption: Vancomycin when administered orally is minimally absorbed into the systemic circulation. Its absorption through intact intestinal mucosa is negligible, which allows oral formulations to concentrate action within the gastrointestinal tract, ideal for treating infections such as Clostridium difficile-associated diarrhea (CDI). However, absorption may increase in cases where the intestinal mucosa is inflamed or compromised, potentially leading to systemic exposure and associated toxicities. Oral vancomycin given for enteric infections results in high local concentrations with minimal systemic absorption, reducing systemic side effects. Distribution: Given the poor systemic absorption of oral vancomycin, plasma distribution is limited when administered orally. When given intravenously (IV), vancomycin distributes widely into body fluids and tissues, including the kidneys, lungs, and heart valves. It crosses the placenta and is present in breast milk. The volume of distribution ranges from 0.4 to 1 L/kg in adults receiving IV dosing, indicating moderate tissue penetration. However, vancomycin penetration into cerebrospinal fluid (CSF) is limited unless the meninges are inflamed. Metabolism: Vancomycin is not significantly metabolized by hepatic enzymes. It remains mostly as the unchanged parent compound in the systemic circulation and excreted primarily by the kidneys. This lack of metabolism reduces the variability of its pharmacokinetics related to liver function and restricts drug-drug interactions mediated by hepatic enzymes such as cytochrome P450. Elimination: The primary route of vancomycin elimination is renal excretion via glomerular filtration. Twenty percent or more of the administered IV dose is recovered unchanged in urine within 24 hours. The elimination half-life ranges from 4 to 6 hours in patients with normal kidney function, but it can be prolonged significantly in patients with impaired renal function, necessitating dose adjustment. Oral vancomycin administered for CDI is mostly excreted unchanged in feces, with minimal renal excretion. Renal function is a critical factor for systemic vancomycin clearance and monitoring of serum levels is advised during systemic therapy to avoid toxicity.

Dosage Forms

Available Dosage Forms: Vancomycin is commercially available in the following oral dosage forms: - Oral capsules containing 125 mg or 250 mg of vancomycin hydrochloride - Oral solution (liquid) formulations such as Firvanq, available as 25 mg/mL concentrations, provided in bottles (e.g., 25 mg/mL, bottles of 50 mL or 100 mL) Dosages for Adults and Adolescents: For treatment of Clostridium difficile-associated diarrhea and Staphylococcus aureus enterocolitis, the typical oral dosing regimen includes: - 125 mg orally four times a day (q6h), administered for 10 to 14 days for initial CDI treatment - For more severe or complicated CDI, doses may escalate to 500 mg orally four times a day, sometimes in conjunction with rectal administration and/or IV metronidazole - Maximum doses up to 2 g per day divided into three to four doses have been used in clinical situations - Duration varies from 7 to 14 days depending on severity of infection, with prolonged or tapered regimens used for recurrent infections Specific Patient Populations: - Patients with severe CDI or complicated infections may require higher doses and adjunctive therapies, including rectal enemas with vancomycin retained every 6 hours - Oral vancomycin is not absorbed systemically, so dose adjustments are generally not required in patients with renal impairment for enteric infections - Pediatric dosing requires careful determination based on weight and indication, though mainly IV formulations are used systemically - Pregnancy use should be guided by obstetric consultation considering benefits and risks - Special attention is required in patients with inflammatory bowel disease or altered intestinal mucosa due to increased potential for systemic absorption leading to toxicity

Mechanism Of Action

Vancomycin is a glycopeptide antibiotic that exerts a bactericidal effect primarily against gram-positive organisms by inhibiting bacterial cell wall synthesis. Its mechanism involves binding tightly to the D-alanyl-D-alanine termini of the nascent peptidoglycan chains, a critical precursor required for cross-linking and proper cell wall formation. This binding sterically hinders the transglycosylation step catalyzed by transglycosylases and the transpeptidation step catalyzed by transpeptidases (penicillin-binding proteins), thereby preventing the incorporation of peptidoglycan subunits into the expanding cell wall and compromising cell wall integrity.

At the cellular level, this disruption leads to weakened cell walls that cannot withstand osmotic pressure, causing cell lysis and death of susceptible bacteria. Vancomycin’s large molecular structure and unique target differentiate it from β-lactam antibiotics, giving it activity against certain β-lactam-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). Unlike β-lactams, which bind to penicillin-binding proteins, vancomycin interferes earlier in the cell wall biosynthesis process by targeting peptidoglycan precursors.

Clinically, vancomycin is especially effective in treating serious infections caused by gram-positive pathogens including MRSA and Clostridium difficile infections localized in the gastrointestinal tract when given orally. Its intravenous form is used for systemic infections. Resistance to vancomycin, such as in vancomycin-resistant enterococci (VRE), involves alteration of the D-alanyl-D-alanine binding site to D-alanyl-D-lactate, reducing affinity and thus antibiotic efficacy, which is a critical concern in clinical practice.

Clinical studies have validated vancomycin's efficacy for severe and complicated gram-positive infections and have influenced guidelines recommending it as a cornerstone for MRSA bacteremia and CDI treatment. Comparative studies show that while newer antibiotics may offer alternative mechanisms or better pharmacokinetics, vancomycin remains a gold standard due to its potent mechanism and established safety profile when appropriately used.

Pharmacological Actions

Bactericidal antibiotic activity against gram-positive bacteria by inhibiting cell wall synthesis
Effective in treatment of infections caused by MRSA and other resistant gram-positive organisms
Activity is limited to extracellular organisms due to poor intracellular penetration
Not effective against gram-negative bacteria due to inability to penetrate outer membrane
Oral formulation acts locally in the gastrointestinal tract against Clostridium difficile without systemic absorption
Intravenous formulation allows systemic bactericidal effects for serious infections including bacteremia and endocarditis
Disrupts peptidoglycan cross-linking by binding D-alanyl-D-alanine residues, inhibiting cell wall biosynthesis
Demonstrates concentration-dependent killing with time-dependent bactericidal efficacy
Lacks significant hepatic metabolism; excreted primarily unchanged via renal elimination
Potential nephrotoxicity and ototoxicity linked to high systemic levels, particularly with IV use
Minimal drug interactions related to metabolism due to negligible cytochrome P450 involvement
Induces lower rates of resistance compared to other antibiotics but emergence of VRE is significant concern
Does not cross blood-brain barrier effectively unless meninges are inflamed
Used synergistically with other antibiotics like aminoglycosides in certain infections

Therapeutic Or Clinical Uses

Treatment of Clostridium difficile-associated diarrhea and pseudomembranous colitis via oral administration
Management of enterocolitis caused by Staphylococcus aureus including MRSA strains when localized in GI tract
Initial and recurrent treatment regimens for severe and complicated Clostridium difficile infection (CDI)
Adjunctive therapy in combination with IV metronidazole and rectal vancomycin for complicated CDI with ileus or megacolon
Systemic intravenous use for serious gram-positive infections including bacteremia, endocarditis, osteomyelitis, and meningitis
Prophylaxis against bacterial infections in patients allergic to β-lactams
Treatment of infections caused by MRSA, including skin and soft tissue infections
Use in healthcare-associated infections with resistant gram-positive pathogens
Management of infections in patients with structural heart disease or prosthetic devices
Alternative treatment for enterococcal infections resistant to other antibiotics
Utilized in patients with penicillin allergy requiring gram-positive coverage
Treatment of patients with renal impairment requires dosing adjustment when used systemically
Recommended by Society of Healthcare Epidemiology of America (SHEA) and Infectious Diseases Society of America (IDSA) guidelines for severe CDI
Supportive treatment in infection control strategies to reduce spread of resistant organisms
Use in clinical settings to prevent recurrence of CDI with tapered or pulsed oral vancomycin regimens

Side Or Adverse Effects

Common gastrointestinal discomfort including nausea and stomach pain
Possible low potassium levels leading to muscle cramps, constipation, and cardiac arrhythmias
Potential nephrotoxicity especially with systemic intravenous use or in patients with existing kidney disease
Ototoxicity risk manifesting as hearing loss or ringing in the ears, particularly with high serum concentrations
Allergic reactions including rash, hives, and in rare cases anaphylaxis
Red man syndrome characterized by flushing, rash, hypotension due to histamine release, typically related to rapid IV infusion
Increased diarrhea severity or development of bloody diarrhea during treatment
Electrolyte imbalances including hypokalemia during prolonged therapy
Injection site reactions with IV administration such as phlebitis
Potential for superinfection with prolonged use leading to resistant organisms or fungal infections
Rare cases of neutropenia and thrombocytopenia reported
Elevated liver enzymes occasionally observed but clinical significance unclear
Local gastrointestinal irritation from oral solution use
Risk of systemic toxicity if oral absorption increases due to compromised intestinal mucosa
Monitoring recommendations to detect early signs of renal or auditory impairment

Precautions

Use cautiously in patients with pre-existing kidney disease or renal impairment
Monitor renal function closely during systemic intravenous therapy to adjust dosing as necessary
Avoid rapid intravenous infusion to reduce risk of red man syndrome; infuse over at least 60 minutes
Use caution in patients with history of hearing problems or ototoxicity risk factors
Careful assessment warranted in patients with inflammatory bowel disease due to potential increased oral absorption
Refrain from unapproved prolonged use or unnecessary dosing to prevent resistance development
Ensure adherence to complete prescribed course to minimize risk of recurrent Clostridium difficile infection
Avoid co-administration with other nephrotoxic or ototoxic drugs without close monitoring
Pregnancy category considerations and use only when clearly needed per obstetric guidance
Storage instructions for oral solutions—refrigeration and discard after 14 days to prevent degradation
Inform patients about potential side effects and importance of reporting auditory changes or signs of hypersensitivity
Use special caution in elderly patients due to increased susceptibility to adverse effects
Assess electrolyte status during prolonged treatment due to risk of hypokalemia
Limit use in breastfeeding mothers unless benefits outweigh potential risks
Use rectal formulations only under medical supervision with appropriate retention techniques

Warnings

Oral vancomycin is not effective for infections outside the gastrointestinal tract due to negligible systemic absorption
Risk of nephrotoxicity and ototoxicity increases with systemic exposure, particularly with IV administration
Potential for causing severe allergic reactions including anaphylaxis mandates readiness for emergency intervention
Red man syndrome is a common infusion-related reaction caused by histamine release with rapid administration
Increased diarrhea or bloody stools during treatment may indicate worsening infection or new superinfection
Monitoring for resistant bacterial strains including vancomycin-resistant enterococci (VRE) is essential to prevent treatment failure
Use with caution in patients receiving concomitant nephrotoxic agents to prevent additive kidney damage
Pregnant or breastfeeding patients must consult healthcare provider before use due to incomplete safety data
Removal of drug due to poor systemic availability from oral use renders it ineffective for systemic infections
Discard unused oral solution after 14 days to avoid microbial contamination and decreased potency
Missed doses should not be doubled to avoid toxicity and ensure therapeutic efficacy
Patients should be advised not to share their medication to prevent inappropriate use and increased resistance risk
Not indicated for viral infections such as influenza or common cold
Serious side effects warrant immediate medical attention, especially auditory changes and renal signs
Adjust dosages appropriately for severe CDI to prevent complications and treatment failures

Contraindication

Known hypersensitivity or allergy to vancomycin or any component of the formulation
Contraindicated for oral use when systemic infection requires intravenous or alternative therapy
Not to be used for treatment of infections caused by organisms resistant to vancomycin
Avoid in patients with documented red man syndrome intolerance to vancomycin without close monitoring
Contraindicated in patients with history of severe adverse reactions to glycopeptide antibiotics
Not recommended for use in viral infections or non-bacterial diarrheas
Avoid oral vancomycin in non-intestinal infections due to minimal absorption and ineffectiveness
Use caution or avoid in neonates and infants unless clinically indicated and dosed appropriately
Not indicated for prophylactic use outside of approved surgical infection management
Contraindicated in patients with severe renal impairment for systemic administration without dose adjustment
Avoid concomitant use with other ototoxic or nephrotoxic drugs unless absolutely necessary
Hypersensitivity reactions contraindicate continuation or re-administration of vancomycin
Contraindicated in patients with known severe electrolyte imbalances unless corrected
Use cautiously in patients with unstable cardiovascular status due to potential infusion reactions
Avoid use in breastfeeding unless benefit outweighs potential risk according to clinical judgment

Drug Interactions

Concurrent use with other nephrotoxic agents (e.g., aminoglycosides, cisplatin, loop diuretics) increases risk of kidney injury
Use with ototoxic drugs (e.g., aminoglycosides, loop diuretics) may potentiate hearing loss or vestibular damage
Additive neuromuscular blocking effects when used with neuromuscular blockers, requiring close monitoring
Potential interaction with diuretics may exacerbate electrolyte disturbances such as hypokalemia
No significant cytochrome P450 mediated drug interactions due to minimal metabolism
May interact with other antibiotics when used concomitantly, affecting therapeutic efficacy or toxicity
Prolonged use with systemic corticosteroids may increase infection risk requiring careful monitoring
Coadministration with metronidazole used in combination regimens for severe CDI
Drugs affecting renal clearance can alter vancomycin serum concentrations necessitating dose adjustments
Oral vancomycin absorption may be increased by drugs altering intestinal permeability and mucosal integrity
Potential interaction with anticoagulants, increasing bleeding risk indirectly by altering gut flora
Minimal interaction with vitamins or herbal supplements but patient history should be evaluated
Drug levels may be affected by procedures enhancing drug removal such as hemodialysis
Concurrent use with cholestyramine or colestipol may bind vancomycin in the gut decreasing efficacy
Reporting all concurrent medications to healthcare providers is essential to avoid adverse interactions

Preparations Of The Drug

Vancomycin oral capsules (125 mg and 250 mg) for treatment of Clostridium difficile and enterocolitis
Oral solution (Firvanq) as 25 mg/mL liquid formulation for precise dosing in patients unable to swallow capsules
Injectable vancomycin hydrochloride formulations for intravenous infusion in systemic infections (not for oral use)
Rectal formulations (retention enemas) prepared in clinical settings for severe complicated CDI management
Compounded oral suspensions prepared from IV formulations when commercial oral solutions are not available
Commercial brands include FIRST-Vancomycin 25, FIRST-Vancomycin 50, and Vancocin series
FDA-approved formulations stored at room temperature (capsules) or refrigerated (oral solutions)
Packets and compounded vancomycin powder forms for oral reconstitution in some healthcare settings
Preparation kits available to ensure appropriate dilution and dosing accuracy for oral use
Liquid preparations require shaking prior to dosing and use of calibrated syringes or measuring devices
Label instructions specify storage conditions to maintain potency and prevent microbial contamination
Non-oral preparations include IV solutions in multiple concentrations for diluted infusion
Manufactured with excipients to enhance stability and palatability of oral liquid forms
Patient information leaflets accompany products to instruct on proper administration and storage
Commercial availability varies globally with various brand names and concentration options