Safety profile of enantiomers vs. racemic mixtures: it's the same?

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: The physicochemical properties of racemates and stereoisomers of medicines can differ significantly, and this may affect the side-effect profile in addition to the pharmacokinetics and intended pharmacology. WHAT THIS STUDY ADDS: This is a study to investigate the profile of adverse drug reactions of racemic and enantiomeric forms of drugs. Our data suggest differences in the safety profile for ofloxacin and omeprazole. This area requires more work to investigate this for other compounds. AIMS: The objective was to investigate the safety profile of four drugs marketed as racemic and enantiomeric forms in France. METHODS: Data from the French PharmacoVigilance Data Base (January 2005 to June 2010) were analysed for four pairs of racemic/isomeric drugs. A case-noncase approach was used to measure the disproportionality of combination between adverse drug reaction (ADR) and exposure to drug. RESULTS: No significant difference in the number of ADRs was observed between Rac-cetirizine/(R)-cetirizine or Rac-citalopram/(S)-citalopram pairs. (S)-Omeprazole induced more haematological effects than Rac-omeprazole. Rac-Ofloxacin induced more haematological, renal and neuropsychiatric ADRs than (S)-ofloxacin, whereas levofloxacin was associated with more reports of musculoskeletal ADRs. CONCLUSIONS: The profile of ADRs could differ for some drugs marketed as racemic and enantiomeric forms. Further studies would be necessary to confirm these data.

Acute colchicine intoxication during clarithromycin administration.

OBJECTIVE: To report a case of colchicine intoxication occurring with institution of clarithromycin. CASE SUMMARY: A 76-year-old man with familial Mediterranean fever (FMF) had received colchicine 1.5 mg daily for 6 years. The patient underwent 7 days of clarithromycin, amoxicillin, and omeprazole treatment for Helicobacter pylori-associated gastritis. Fever, abdominal pain, and diarrhea occurred 3 days after treatment initiation. On day 8, dehydration, pancytopenia, metabolic acidosis, and increased lipase level necessitated hospitalization. Alopecia was observed 2 weeks later. The patient recovered fully after the colchicine dosage was reduced to 0.5 mg/day and rehydration was performed. The previous dosage was then reinstituted without adverse reaction. An objective causality assessment revealed that the adverse event was probable. DISCUSSION: Continuous colchicine administration is used in treatment of microcrystalline arthritis, Behcet's disease, and FMF. Colchicine is primarily eliminated through biliary excretion. Renal elimination and cytochrome P450 metabolism play a less significant role. Colchicine is also a substrate of P-glycoprotein, a transporter involved in cellular efflux and elimination of numerous drugs. Three cases of intoxication have been reported when colchicine was combined with erythromycin, josamycin, or clarithromycin. Macrolides are inhibitors of P-glycoprotein and cytochrome P450-dependent enzymes and may decrease colchicine's biliary excretion through P-glycoprotein inhibition. CONCLUSIONS: Coadministration of colchicine and macrolides may impair colchicine elimination, resulting in excess drug exposure and toxicity. To this end, colchicine should be used with extreme caution in patients receiving P-glycoprotein inhibitors, particularly if they are elderly and/or renally compromised.

Tenofovir-related Fanconi syndrome with nephrogenic diabetes insipidus in a patient with acquired immunodeficiency syndrome: the role of lopinavir-ritonavir-didanosine.

Tenofovir-related tubular damage, like all other recently reported cases, occurred in patients receiving the protease inhibitor (PI) ritonavir, often with lopinavir. Increased plasma concentrations of didanosine were also observed after the addition of tenofovir. It was suspected that tenofovir with PIs interacted with renal organic anion transporters, leading to nephrotoxic tubular concentrations of tenofovir and systemic accumulation of didanosine. Until there is a better understanding of these interactions, close monitoring is recommended for patients receiving tenofovir, PIs, and didanosine.

Coagulation disorders in patients with cirrhosis and severe sepsis.

BACKGROUND: In patients with cirrhosis, severe sepsis may stimulate the extrinsic coagulation pathway resulting in thrombin generation and fibrin formation. AIMS: To compare 23 patients with severe sepsis to 13 infected patients without severe sepsis and 18 patients without infection. METHODS: Zymogen forms of clotting factors involved in the extrinsic pathway (i.e., factors VII + X, V, prothrombin), and the presence of soluble fibrin were assessed. RESULTS: Zymogen forms of clotting factors were significantly lower, while Child-Pugh score and the proportion of patients with soluble fibrin were higher in the severe-sepsis group than in the other groups. Decreased zymogen levels were independently correlated with an elevated Child-Pugh score and the presence of severe sepsis. In the severe-sepsis group, after adjustment for the severity of cirrhosis, decreased zymogen levels were associated with significant increases in the relative risk ratios of in-hospital death. CONCLUSIONS: Cirrhotic patients with severe sepsis have decreased blood levels of zymogen forms of factors VII+X, V, and prothrombin, which may be due not only to the severity of cirrhosis but also, at least in part, to the consumption of these zymogens by the extrinsic coagulation pathway.

Terlipressin inhibits in vivo aortic iNOS expression induced by lipopolysaccharide in rats with biliary cirrhosis.

In cirrhosis, lipopolysaccharide (LPS, a product of Gram-negative bacteria) in the blood may cause septic shock. LPS-elicited induction of arterial inducible nitric oxide synthase (iNOS) results in nitric oxide (NO)-induced vasodilation, which causes arterial hypotension and hyporeactivity to alpha(1)-adrenergic constrictors. In vitro studies have suggested that vasopressin inhibits iNOS expression in cultured vascular smooth muscle cells exposed to LPS. Thus, the aim of this study was to investigate the effects of terlipressin administration (a vasopressin analog) on in vivo LPS-induced aortic iNOS in rats with cirrhosis. LPS (1 mg/kg, intravenously) was administered followed by the intravenous administration of terlipressin (0.05 mg/kg, intravenously) or placebo 1 hour later. Arterial pressure was measured, and contractions to phenylephrine (an alpha(1)-adrenoceptor agonist), iNOS activity, and iNOS expressions (mRNA and protein) were investigated in isolated aortas. LPS-induced arterial hypotension and aortic hyporeactivity to phenylephrine were abolished in rats that received terlipressin. LPS-induced aortic iNOS activity and expression were suppressed in terlipressin-treated rats. In conclusion, in LPS-challenged rats with cirrhosis, terlipressin administration inhibits in vivo LPS-induced aortic iNOS expression. Terlipressin administration may be a novel approach for the treatment of arterial hypotension and hyporeactivity to alpha(1)-adrenergic constrictors in patients with cirrhosis and septic shock.