Dalfopristin
Also known as: Pristinamycin IIA derivative, Quinupristin/Dalfopristin, RP 54476, Synercid
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Summary
Dalfopristin is a cyclic depsipeptide antibiotic belonging to the streptogramin B class and is marketed in combination with quinupristin (Synercid). It is administered intravenously by prescription and is approved for treatment of serious infections caused by susceptible Gram‑positive bacteria, including resistant strains. The drug works together with quinupristin to achieve synergistic antibacterial activity.
Mechanism of Action
Dalfopristin, as a streptogramin B agent, binds to the bacterial 50S ribosomal subunit and interferes with peptide chain elongation, thereby inhibiting protein synthesis. When combined with the streptogramin A component quinupristin, the two molecules bind distinct sites on the ribosome, producing a synergistic bacteriostatic‑to‑bactericidal effect against susceptible Gram‑positive organisms.
What the Research Shows
The literature highlights several aspects of dalfopristin use. A 2024 meta‑analysis of Enterococcus faecalis isolates reported a rising resistance trend to the quinupristin‑dalfopristin combination over time, suggesting widespread clinical exposure. A 2012 review of adenotonsillar disease noted that quinupristin‑dalfopristin possesses high intracellular activity and may target bacteria persisting in biofilms, although no clinical trial data were presented. A 2022 review of Staphylococcus aureus resistance mechanisms listed streptogramin B agents, including quinupristin/dalfopristin, among the antibiotics affected by MLS‑B resistance pathways, underscoring the molecular basis of emerging resistance.
Reported Benefits
Evidence indicates that dalfopristin, when paired with quinupristin, can act against intracellular and biofilm‑embedded Gram‑positive pathogens, offering a therapeutic option for infections where conventional antibiotics may fail. Its approved status reflects regulatory recognition of its utility in serious, resistant infections, and its synergistic mechanism can enhance bacterial killing compared with either component alone.
Limitations of the Evidence
The primary limitation is the documented increase in resistance to the quinupristin‑dalfopristin combination, as shown in recent global surveillance of E. faecalis. Available literature consists mainly of observational resistance data and mechanistic reviews, without recent randomized clinical trials evaluating efficacy or safety. Consequently, the strength of clinical evidence for specific indications remains modest.
How It Is Administered
Dalfopristin is supplied only for intravenous infusion and is used under prescription. The drug is formulated as part of the fixed‑dose quinupristin‑dalfopristin combination (Synercid) and is administered by healthcare professionals in a hospital or clinical setting.
Routes of Administration
Goals & Uses
- Bacteremia caused by susceptible Gram‑positive organismsAntibacterialHigh
- Vancomycin-resistant Enterococcus faecium (VREF) infectionsAntibacterialHigh
- Complicated skin and skin structure infections (cSSSI)AntibacterialHigh
- Hospital-acquired pneumonia (off-label)AntibacterialLow
- Complicated skin and skin‑structure infectionsAntibacterialHigh
Contraindications
- Severe hepatic impairment (Child‑Pugh C)Liver DiseaseModerate
- Hypersensitivity to streptogramin antibioticsAllergyHigh
- Concomitant use of CYP3A4-metabolized drugs with narrow therapeutic indexDrug InteractionHigh
- Hypersensitivity to streptograminsAllergyHigh
Adverse Effects
- Hypersensitivity reactionsImmunologicRare
- Elevated liver enzymes (AST/ALT)HepatotoxicityUncommon
- Infusion site reactions (pain, inflammation, thrombophlebitis)LocalCommon
- Nausea and vomitingGastrointestinalCommon
- Rash or pruritusDermatologicCommon
- Phlebitis at infusion siteLocal/vascularCommon
- Elevated liver enzymes (ALT, AST)HepaticUncommon
- Arthralgia and myalgiaMusculoskeletalCommon
- HyperbilirubinemiaHepaticCommon
Drug Interactions
- HMG-CoA reductase inhibitors (statins)Moderate
- MidazolamModerate
- CYP3A4 inducers (e.g., rifampin, carbamazepine)Moderate
- WarfarinModerate
- CyclosporineHigh
- TacrolimusHigh
- CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin)Moderate
Population Constraints
- Hepatic impairmentOrgan FunctionRelative
- Neonates and infants < 1 monthAgeAbsolute
- Pediatric patientsAgeRelative
- Pregnancy (Category B)PregnancyRelative
- Pregnant womenReproductiveRelative
Regulatory Status
- European UnionApprovedApproved: Serious infections caused by susceptible Gram‑positive organismsMarketed under the same combination product.
- United StatesApprovedApproved: Complicated skin and skin‑structure infections, Bacteremia caused by susceptible Gram‑positive bacteriaApproved as part of quinupristin/dalfopristin (Synercid) for IV use.
- United KingdomApprovedApproved: Vancomycin-resistant Enterococcus faecium infections, Complicated skin and skin structure infectionsAvailable as Synercid; used as reserve antibiotic for resistant organisms
Approved in the US and EU as part of the fixed‑dose combination quinupristin/dalfopristin; not marketed as a standalone product.
Evidence & Sources
- Journal ArticleHighGuan L, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleModerateZautner AE2012-01-01T00:00:00.000000Z
- Journal ArticleModerateMlynarczyk-Bonikowska B, et al.2022-01-01T00:00:00.000000Z
Frequently Asked Questions
What type of infections is dalfopristin used for?
Dalfopristin is used in combination with quinupristin for serious infections caused by susceptible Gram‑positive bacteria, especially those resistant to other antibiotics, such as certain strains of Staphylococcus aureus and Enterococcus faecalis.
How does resistance to dalfopristin develop?
Resistance mechanisms include modifications of the 50S ribosomal binding site and acquisition of MLS‑B resistance genes, which reduce the drug’s ability to inhibit protein synthesis, as described in reviews of Staphylococcus aureus resistance.
Can dalfopristin treat biofilm‑associated infections?
A review of adenotonsillar disease notes that quinupristin‑dalfopristin has high intracellular activity and can target bacteria within biofilms, suggesting potential utility against biofilm‑associated Gram‑positive infections, though clinical data are limited.
Is dalfopristin safe for outpatient use?
The drug is formulated for intravenous infusion and is administered in a clinical setting; safety data and dosing guidance are not detailed in the cited literature, and it is not indicated for outpatient self‑administration.
Why is resistance to dalfopristin increasing?
A 2024 meta‑analysis reported a temporal rise in resistance rates to the quinupristin‑dalfopristin combination among Enterococcus faecalis isolates, reflecting broader global trends of antimicrobial resistance and the selective pressure of extensive clinical use.
What is Dalfopristin?
Dalfopristin is a cyclic depsipeptide antibiotic belonging to the streptogramin B class and is marketed in combination with quinupristin (Synercid). It is administered intravenously by prescription and is approved for treatment of serious infections caused by susceptible Gram‑positive bacteria, including resistant strains. The drug works together with quinupristin to achieve synergistic antibacterial activity.
What is Dalfopristin used for?
Dalfopristin is educationally associated with: Bacteremia caused by susceptible Gram‑positive organisms, Vancomycin-resistant Enterococcus faecium (VREF) infections, Complicated skin and skin structure infections (cSSSI), Hospital-acquired pneumonia (off-label), Complicated skin and skin‑structure infections. Educational only — not medical advice.
How is Dalfopristin administered?
Recorded routes of administration: Intravenous.
What are the potential side effects of Dalfopristin?
Reported adverse effects include: Hypersensitivity reactions, Elevated liver enzymes (AST/ALT), Infusion site reactions (pain, inflammation, thrombophlebitis), Nausea and vomiting, Rash or pruritus, Phlebitis at infusion site, Elevated liver enzymes (ALT, AST), Arthralgia and myalgia, Hyperbilirubinemia. This list is not exhaustive — consult a qualified clinician.
Who should avoid Dalfopristin?
Recorded contraindications: Severe hepatic impairment (Child‑Pugh C), Hypersensitivity to streptogramin antibiotics, Concomitant use of CYP3A4-metabolized drugs with narrow therapeutic index, Hypersensitivity to streptogramins. Consult a qualified clinician before use.