Quinupristin/dalfopristin, or quinupristin-dalfopristin, (pronunciation: kwi NYOO pris tin / dal FOE pris tin) (trade name Synercid) is a combination of two antibiotics used to treat infections by staphylococci and by vancomycin-resistant Enterococcus faecium. Quinupristin and dalfopristin are both streptogramin antibiotics, derived from pristinamycin. Quinupristin is derived from pristinamycin IA; dalfopristin from pristinamycin IIA. They are combined in a weight-to-weight ratio of 30% quinupristin to 70% dalfopristin. Administration
Intravenous, usually 7.5 mg/kg every 8 hours (infections/life threatening VRSA); every 12 hours (skin infections). No renal dosing adjustments, hepatic dosing adjustments are not defined, consider reducing dose. Mechanism of action
Quinupristin and dalfopristin are protein synthesis inhibitors in a synergistic manner. While each of the two is only a bacteriostatic agent, the combination shows bactericidal activity. Dalfopristin binds to the 23S portion of the 50S ribosomal subunit, and changes the conformation of it, enhancing the binding of quinupristin by a factor of about 100. In addition, it inhibits peptidyl transfer. Quinupristin binds to a nearby site on the 50S ribosomal subunit and prevents elongation of the polypeptide, as well as causing incomplete chains to be released. Pharmacokinetics
Clearance by the liver CYP450:3A4 inhibitor, half-life quinupristin 0.8 hours, dalfopristin 0.7 hours (with persistence of effects for 9–10 hours). Excretion: Quinupristin:  85% feces, 15% urine; Dalfopristin: 81% feces, 19% urine

Side effects
Serious:

C.diff-associated diarrhea
superinfection
anaphylactoid reactions
angioedemaCommon:

Joint aches (arthralgia) or muscle aches (myalgia)
Nausea, diarrhea (C. diff associated) or vomiting
Rash or itching
Headache
Hyperbilirubinemia
Anemia
Thrombophlebitis

Drug interactions
The drug inhibits P450 and enhances the effects of terfenadine, astemizole, indinavir, midazolam, calcium channel blockers, warfarin, cisapride and ciclosporin. References


== Further reading ==
Oral lichen planus (OLP) tends to present bilaterally as mostly white lesions on the inner cheek, although any mucosal site in the mouth may be involved. Other sites, in decreasing order of frequency, may include the tongue, lips, gingivae, floor of the mouth, and very rarely, the palate.Generally, oral lichen planus tends not to cause any discomfort or pain, although some people may experience soreness when eating or drinking acidic or spicy foodstuffs or beverages. When symptoms arise, they are most commonly associated with the atrophic and ulcerative subtypes. These symptoms can include a burning sensation to severe pain. They may also experience mucosal bleeding in response to mild trauma, such as toothbrushing. Additionally, the Koebner phenomenon (the development of new lesions at sites of trauma) is not only present in cutaneous lichen planus (CLP) but can also occur in the setting of OLP. Residual postinflammatory hyperpigmentation has been reported in association with OLP, manifesting as brown to black pigmentation on the oral mucosa and may most likely occur in dark-skinned individuals.OLP may occur as a sole manifestation of the disease or in conjunction with other clinical manifestations of LP, including cutaneous LP, genital LP, nail LP, and lichen planopilaris (scalp LP). Causes
Cutaneous LP is a self-limiting condition. It usually resolves within 6 to 12 months. Oral LP is a non infectious, chronic inflammatory condition that involves the oral mucosa and may be accompanied by skin lesions.