Vancomycin (Oral)
vancomycin hydrochloride capsules & oral solution (Vancocin, Firvanq)
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Clostridioides difficile-associated diarrhea (CDAD / CDI) | Adults and pediatrics <18 years | Monotherapy | FDA Approved |
| Enterocolitis caused by Staphylococcus aureus (including MRSA) | Adults and pediatrics <18 years | Monotherapy | FDA Approved |
Oral vancomycin acts locally within the gastrointestinal lumen and is not effective for systemic infections. It remains a first-line treatment option for C. difficile infection across all severity categories. The 2021 IDSA/SHEA focused update suggests fidaxomicin as preferred over vancomycin for initial and recurrent CDI based on lower recurrence rates, but oral vancomycin remains an acceptable alternative, particularly where fidaxomicin is unavailable or cost-prohibitive. For fulminant CDI, high-dose oral vancomycin combined with rectal vancomycin enemas and intravenous metronidazole is the recommended regimen.
CDI prophylaxis during systemic antibiotics: Low-dose oral vancomycin (125 mg once or twice daily) used in patients with recurrent CDI history who require systemic antibiotics. Evidence quality: Low (small retrospective studies and expert opinion).
Long-term suppressive therapy for multiply-recurrent CDI: Extended low-dose vancomycin taper over several months in patients awaiting or ineligible for faecal microbiota transplantation. Evidence quality: Low (case series, expert opinion).
Dosing
Adult Dosing — By Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Initial CDI — non-severe | 125 mg PO QID | 125 mg PO QID × 10 days | 500 mg/day | IDSA/SHEA 2017/2021; fidaxomicin preferred if available (2021 update) No dose escalation needed for non-severe disease |
| Initial CDI — severe (WBC ≥15,000 or SCr ≥1.5 mg/dL) | 125 mg PO QID | 125 mg PO QID × 10 days | 500 mg/day | Same dose as non-severe per IDSA/SHEA 2017; some institutions use 250 mg QID for severe Monitor closely for progression to fulminant |
| Fulminant CDI (hypotension, shock, ileus, toxic megacolon) | 500 mg PO or NG QID | 500 mg PO/NG QID + 500 mg rectal q6h | 2 g/day PO + rectal | Add IV metronidazole 500 mg q8h; rectal dose: 500 mg in 100 mL NS as retention enema Surgical consult for colectomy if deteriorating (IDSA/SHEA 2017) |
| First CDI recurrence — standard course | 125 mg PO QID | 125 mg PO QID × 10 days | 500 mg/day | Fidaxomicin preferred (IDSA/SHEA 2021); consider tapered/pulsed vancomycin as alternative Especially if initial episode treated with standard vancomycin |
| CDI recurrence — tapered and pulsed regimen | 125 mg PO QID × 10–14 days | 125 mg BID × 7 days, then 125 mg QD × 7 days, then 125 mg q2–3 days × 2–8 weeks | 500 mg/day (initial phase) | Total duration ~6–10 weeks; IDSA/SHEA 2017 recommended regimen for recurrence Pulsed phase exploits spore germination cycles |
| Multiple CDI recurrences (≥2 prior episodes) | 125 mg PO QID | Tapered/pulsed (as above) OR followed by rifaximin chaser | 500 mg/day | Options: fidaxomicin, vancomycin taper/pulse, vancomycin then rifaximin 400 mg TID × 20 days, or FMT ID consult recommended; consider bezlotoxumab if high-risk |
| Staphylococcal enterocolitis | 500 mg–2 g/day PO div TID–QID | 500 mg–2 g/day div TID–QID × 7–10 days | 2 g/day | Dose dependent on severity; per FDA PI Rare indication; confirm diagnosis before treating |
Pediatric Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| CDI — children <18 years | 40 mg/kg/day PO div TID–QID | 40 mg/kg/day × 7–10 days | 2 g/day | Per FDA PI (Vancocin/Firvanq); oral solution preferred for dose accuracy in young children Tapered/pulsed regimen for recurrence: same principle, weight-based |
| Staphylococcal enterocolitis — children <18 years | 40 mg/kg/day PO div TID–QID | 40 mg/kg/day × 7–10 days | 2 g/day | Per FDA PI Use oral solution formulation for accurate dosing |
The tapered and pulsed vancomycin regimen exploits the biology of C. difficile spore germination. Standard-dose vancomycin kills vegetative cells but cannot eradicate spores. After stopping a standard course, spores germinate into vegetative bacteria, causing relapse. The pulsed regimen keeps intermittent antibiotic exposure aligned with spore germination cycles (every 2–3 days), killing newly germinated organisms over several weeks until the spore burden is sufficiently reduced. This approach has been recommended by the IDSA/SHEA 2017 guideline as an option for first CDI recurrence and is widely used in clinical practice, although head-to-head comparison with fidaxomicin for recurrence prevention is limited.
When oral capsules or Firvanq solution are unavailable, the intravenous vancomycin preparation can be diluted and administered orally. This is a common and accepted practice, particularly in inpatient settings, and is supported by the FDA PI for certain formulations. The IV solution has a bitter taste; mixing with a flavouring syrup or administering via nasogastric tube improves tolerability. Ensure the product used is labelled for both IV and oral use.
Pharmacology
Mechanism of Action
Vancomycin is a tricyclic glycopeptide antibiotic that inhibits bacterial cell wall synthesis by binding to the D-alanyl-D-alanine terminus of peptidoglycan precursors, preventing cross-linking and causing cell lysis. When administered orally, vancomycin acts locally within the intestinal lumen, achieving very high intraluminal concentrations (typically exceeding 100 mcg/g in feces) that far exceed the MIC of C. difficile (MIC ≤2 mcg/mL for susceptible strains). Vancomycin has bactericidal activity against C. difficile vegetative cells but cannot kill spores, which is the primary reason for disease recurrence after standard courses. The drug also has activity against S. aureus including MRSA in the intestinal lumen, supporting its use for staphylococcal enterocolitis.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Poorly absorbed orally; bioavailability <5% in healthy GI tract | Acts locally in the GI lumen; not effective for systemic infections. However, significant systemic absorption can occur with severe mucosal inflammation (e.g., fulminant CDI, inflammatory bowel disease) |
| Distribution | Confined primarily to GI tract after oral dosing; fecal concentrations typically 500–1,000× MIC90 of C. difficile at standard dosing | Intraluminal concentrations far exceed MIC for C. difficile; if systemically absorbed, distributes similarly to IV (Vd 0.3–0.43 L/kg, ~55% protein bound) |
| Metabolism | No apparent metabolism; no active metabolites | No CYP450 involvement; no metabolic drug interactions expected |
| Elimination | Excreted almost entirely unchanged in feces after oral administration | If systemically absorbed (inflamed mucosa), renal elimination applies and dose-related nephrotoxicity becomes a concern, particularly in patients >65 years or with pre-existing renal impairment |
Side Effects
The following adverse reaction data are from two Phase 3 clinical trials in 260 adults treated with vancomycin oral 125 mg QID for CDI (median age 67 years; mean treatment duration 9.4 days).
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Nausea | 17% | Most common GI complaint; usually mild; may improve by taking with food |
| Abdominal pain | 15% | Distinguish from worsening CDI; abdominal distension or new ileus warrants urgent evaluation |
| Hypokalemia | 13% | Likely multifactorial (diarrheal losses + critical illness); monitor potassium and replace as needed |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Vomiting | ≥5% | May impact drug delivery; if persistent, consider nasogastric administration or switch to rectal route |
| Nephrotoxicity (renal impairment, creatinine increase) | 5% | Median onset Day 16 (typically within 1 week after treatment completion); risk increased in patients >65 years (FDA PI) |
| Diarrhea (non-CDI) | ≥5% | Distinguish from CDI relapse or treatment failure; may reflect antibiotic-associated dysbiosis |
| Flatulence | ≥5% | Usually mild and self-limiting |
| Headache | ≥5% | Non-specific; assess hydration status |
| Peripheral edema | ≥5% | May reflect underlying comorbidities; monitor renal function if new onset |
| Fatigue | ≥5% | Often multifactorial in hospitalised CDI patients |
| Back pain | ≥5% | Non-specific |
| Urinary tract infection | ≥5% | Likely coincidental in hospitalised elderly population; not directly drug-related |
| Fever | ≥5% | Distinguish from drug fever versus ongoing CDI or secondary infection |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Nephrotoxicity (renal failure) | 5% (higher in >65 years) | Median Day 16 (often 1 wk post-completion) | Monitor creatinine during and after treatment; hold or discontinue if significant rise; particularly important in patients >65 years even with normal baseline renal function |
| Ototoxicity (hearing loss, tinnitus) | Very rare (primarily reported with IV) | Variable | Risk relevant only if significant systemic absorption occurs; audiometric monitoring if concurrent ototoxic agents |
| Severe dermatologic reactions (DRESS, SJS/TEN, AGEP, LABD) | Very rare | Days to weeks | Discontinue immediately at first sign; do not rechallenge; dermatology consult |
| Superinfection / non-susceptible organism overgrowth | Uncommon | During or after treatment | Monitor for new infections; oral vancomycin disrupts normal gut flora despite targeting C. difficile |
Although oral vancomycin is considered to have negligible systemic absorption in healthy intestinal mucosa, the FDA PI documents a 5% nephrotoxicity rate in clinical trials. This is attributed to systemic absorption through inflamed colonic mucosa in patients with active CDI. The risk is particularly elevated in patients over 65 years of age, who should have renal function monitored during and after treatment even if their baseline creatinine is normal. Nephrotoxicity typically manifests within one week after completing therapy (median onset Day 16 of the study period), suggesting a delayed presentation that may be missed if follow-up is not arranged.
Drug Interactions
No formal drug interaction studies have been conducted with oral vancomycin (FDA PI). Because systemic absorption is normally negligible, pharmacokinetic interactions are unlikely. However, intraluminal binding interactions and potential systemic interactions in patients with significant mucosal absorption should be considered.
Monitoring
-
Stool Frequency & Consistency
Daily during treatment
Routine Track bowel movements for treatment response. Clinical improvement (formed stools, reduced frequency) is expected within 48–72 hours. Do not repeat C. difficile toxin testing during treatment as tests may remain positive despite clinical cure. -
Serum Creatinine
Baseline; during and after treatment in patients >65
Routine Nephrotoxicity risk increased in elderly patients even after oral administration (5% in trials). Monitor during treatment and for at least 1 week after completion. Particular vigilance in patients with pre-existing renal impairment, inflammatory bowel disease, or those receiving concurrent nephrotoxins. -
Serum Potassium
Baseline, then as clinically indicated
Routine Hypokalemia occurred in 13% of trial participants, likely driven by diarrheal losses. Replace aggressively in patients with cardiac comorbidities or concurrent medications that lower potassium. -
Vancomycin Serum Levels
If significant systemic absorption suspected
Trigger-based Consider measuring serum vancomycin in patients with renal insufficiency, severe inflammatory bowel disease, fulminant colitis, or those also receiving IV aminoglycosides. Clinically significant serum concentrations have been documented after oral dosing in these populations. -
Recurrence Surveillance
4–8 weeks post-treatment
Routine CDI recurrence occurs in approximately 20–25% of patients after a standard vancomycin course. Advise patients to report return of watery diarrhea. Test only symptomatic patients; do not perform test-of-cure in asymptomatic patients. -
Signs of Fulminant Progression
Continuously during inpatient treatment
Routine Monitor for abdominal distension, new ileus (decrease in bowel sounds, cessation of diarrhea with worsening abdominal pain), rising lactate, haemodynamic instability, or WBC >25,000. These warrant urgent escalation to fulminant CDI management and surgical consultation.
Contraindications & Cautions
Absolute Contraindications
- Known hypersensitivity to vancomycin — documented anaphylaxis or severe dermatologic reaction (DRESS, SJS/TEN, LABD) to vancomycin
Relative Contraindications (Specialist Input Recommended)
- Concurrent inflammatory bowel disease (IBD) — increased systemic absorption through chronically inflamed mucosa; monitor serum vancomycin levels and renal function closely
- Severe renal impairment — although oral vancomycin is not expected to produce systemic levels, patients with severe CDI and concurrent renal impairment may accumulate vancomycin if absorption occurs; ID or pharmacy consult recommended
Use with Caution
- Patients >65 years — increased nephrotoxicity risk (FDA PI); monitor renal function during and after treatment
- Fulminant CDI with ileus — oral delivery to the colon may be impaired; add rectal vancomycin enemas and IV metronidazole per guideline recommendations
- Concurrent bile acid sequestrant therapy — may bind and inactivate vancomycin in the GI lumen; separate doses by 3–4 hours or discontinue sequestrant during CDI treatment
- Patients who cannot swallow capsules — use oral solution (Firvanq) or reconstituted IV formulation given orally; consider NG tube in critically ill patients
Nephrotoxicity including renal failure, renal impairment, and blood creatinine increases has been reported following oral vancomycin therapy in randomised controlled clinical studies. The risk is increased in patients over 65 years of age. In geriatric patients, including those with normal baseline renal function, renal function should be monitored during and following treatment to detect potential vancomycin-induced nephrotoxicity.
Orally administered vancomycin is not effective for the treatment of infections other than C. difficile-associated diarrhea and staphylococcal enterocolitis. Parenteral administration of vancomycin is not effective for CDI. The route of administration must match the type of infection being treated.
Patient Counselling
Purpose of Therapy
Oral vancomycin treats an intestinal infection caused by Clostridioides difficile bacteria, which causes severe diarrhea, abdominal pain, and sometimes fever. The antibiotic works inside the gut and is not absorbed into the rest of the body in meaningful amounts. It is important to complete the full course even when symptoms improve, because stopping early can lead to the infection coming back.
How to Take
Swallow capsules whole with water. If using the oral liquid (Firvanq), shake well before each dose and measure carefully with the provided syringe. The liquid should be stored in the refrigerator and discarded after 14 days. Take the medication at evenly spaced intervals (usually every 6 hours) for the full number of days prescribed.
Sources
- Vancocin (vancomycin hydrochloride) Capsules — Full Prescribing Information. ANI Pharmaceuticals, Inc. Revised July 2024. DailyMed Primary regulatory source for FDA-approved indications, dosing (125 mg QID × 10 days for CDI), adverse reactions (n=260 trial data), and nephrotoxicity warnings for oral vancomycin capsules.
- Firvanq (vancomycin hydrochloride for oral solution) — Full Prescribing Information. CutisPharma, Inc. Revised 2021. FDA Label Regulatory source for the oral solution formulation including reconstitution, storage instructions, and pediatric dosing (40 mg/kg/day).
- McDonald LC, Gerding DN, Johnson S, et al. Clinical practice guidelines for Clostridium difficile infection in adults and children: 2017 update by IDSA and SHEA. Clin Infect Dis. 2018;66(7):e1–e48. doi:10.1093/cid/cix1085 Landmark 2017 CDI guideline establishing vancomycin (not metronidazole) as first-line for all severity categories, including tapered/pulsed regimens for recurrence and fulminant CDI management.
- Johnson S, Lavergne V, Skinner AM, et al. Clinical practice guideline by IDSA and SHEA: 2021 focused update guidelines on management of Clostridioides difficile infection in adults. Clin Infect Dis. 2021;73(5):e1029–e1044. doi:10.1093/cid/ciab549 2021 focused update recommending fidaxomicin over vancomycin for initial and recurrent CDI (conditional recommendation); vancomycin remains an acceptable alternative.
- Kelly CR, Fischer M, Allegretti JR, et al. ACG clinical guidelines: prevention, diagnosis, and treatment of Clostridioides difficile infections. Am J Gastroenterol. 2021;116(6):1124–1147. doi:10.14309/ajg.0000000000001278 ACG guideline providing complementary treatment recommendations including both vancomycin and fidaxomicin as first-line for non-severe CDI, and vancomycin taper/pulse for recurrence.
- Louie TJ, Miller MA, Mullane KM, et al. Fidaxomicin versus vancomycin for Clostridium difficile infection. N Engl J Med. 2011;364(5):422–431. doi:10.1056/NEJMoa0910812 Phase 3 RCT demonstrating non-inferior clinical cure but lower recurrence rates with fidaxomicin versus vancomycin 125 mg QID for CDI.
- Cornely OA, Crook DW, Esposito R, et al. Fidaxomicin versus vancomycin for infection with Clostridium difficile in Europe, Canada, and the USA: a double-blind, non-inferiority, randomised controlled trial. Lancet Infect Dis. 2012;12(4):281–289. doi:10.1016/S1473-3099(11)70374-7 Second Phase 3 RCT confirming fidaxomicin non-inferiority for clinical cure with superior sustained response versus vancomycin.
- Guery B, Menichetti F, Anber V, et al. Extended-pulsed fidaxomicin versus vancomycin for Clostridium difficile infection in patients 60 years and older (EXTEND): a randomised, controlled, open-label, phase 3b/4 trial. Lancet Infect Dis. 2018;18(3):296–307. doi:10.1016/S1473-3099(17)30751-X EXTEND trial demonstrating superior sustained cure with extended-pulsed fidaxomicin versus vancomycin in older adults.
- Levine DP. Vancomycin: a history. Clin Infect Dis. 2006;42(Suppl 1):S5–S12. doi:10.1086/491709 Comprehensive historical review of vancomycin from discovery to modern use, covering mechanism, formulations, and evolving clinical applications.
- Shen A. Clostridium difficile toxins: mediators of inflammation. J Innate Immun. 2012;4(2):149–158. doi:10.1159/000332946 Mechanistic review of C. difficile toxin-mediated colitis, providing context for why local intraluminal antibiotic therapy is the appropriate approach.
- Pettit NN, DePestel DD, Fohl AL, et al. Risk factors for systemic vancomycin exposure following administration of oral vancomycin for the treatment of Clostridium difficile infection. Pharmacotherapy. 2015;35(2):119–126. doi:10.1002/phar.1538 Study characterising risk factors for detectable serum vancomycin levels after oral dosing, including renal impairment, ICU admission, and longer treatment duration.
- Pogue JM, DePestel DD, Kaul DR, et al. Systemic absorption of oral vancomycin in patients with Clostridium difficile infection. Scand J Infect Dis. 2013;45(5):396–398. doi:10.3109/00365548.2012.737475 Case series documenting measurable serum vancomycin concentrations in patients receiving oral vancomycin for CDI, supporting the need for monitoring in high-risk patients.