Accidental overdose of intravenous ofloxacin with benign outcome

Plasma protein binding of gyrase inhibitors

Plasma protein binding of a wide range of gyrase inhibitors in clinical practice or trials has been determined by ultrafiltration to determine structure-protein binding relationships. The protein binding was independent of overall lipophilicity. In particular, the "western" part of the "quinolone" skeleton, consisting of a heterocyclus at position 7 and varying substituents at position 8, strongly influences the extent of protein binding, indicating that this part interacts with the plasma protein. In contrast, substituents in position N1 do not show an effect on the protein binding in this series of compounds.

Association of a Tourette-like syndrome with ofloxacin

OBJECTIVE

To describe the association between the use of the fluoroquinolone ofloxacin in an elderly man and an unusual acute encephalopathy with characteristics suggestive of Tourette's syndrome.

CASE SUMMARY

An unusual syndrome was observed in a 71-year-old man temporally related to the initiation of ofloxacin therapy that resolved completely after discontinuation of the drug. The most remarkable phenomena were spitting and profuse swearing; other features were echolalia, echopraxia, orofacial and limb automatisms, hypersalivation, and amnesia for the episode on recovery. The clinical syndrome had several features in common with Tourette's syndrome and possibly with frontal lobe onset complex partial seizures. The electroencephalographic, neuroradiologic, and cerebrospinal fluid examinations were normal.

DISCUSSION

The reported neurotoxic effects of the fluoroquinolones include insomnia, seizures, delirium, and psychosis, best explained by the gamma-aminobutyric acid-antagonistic properties of this class of drugs. This is the first reported case of a Tourette-like syndrome associated with the use of any quinolone, suggesting a possible interaction with central dopaminergic neurotransmitter systems.

CONCLUSIONS

Use of drugs such as ofloxacin that have improved central nervous system penetration, disease- or age-related reductions in renal function, concomitant use of drugs such as theophylline and nonsteroidal antiinflammatory drugs, and possibly increased pharmacodynamic sensitivity place the elderly at special risk for quinolone neurotoxicity. Dosing modifications and an awareness of possible central nervous system adverse effects are warranted.

Tolerability of fluoroquinolone antibiotics. Past, present and future

New fluoroquinolones have been in clinical use for 10 years and have an excellent record of safety and tolerance. The main elements of their adverse reaction profile were predictable from human experience with precursor naphthyridines and quinolones, and from toxicological studies in animals. Thus gastrointestinal reactions (1 to 5%), skin disturbances (less than 2.5%) and central nervous system (CNS) effects (usually around 1 to 2%) were anticipated. Individual group members exhibit particular properties in relation to their chemical structures, for example the phototoxicity associated with 8-halogenation of the nucleus and found to be a particular problem with lomefloxacin and sparfloxacin. Other members, for example ofloxacin, are linked to a higher than usual incidence of CNS reactions and psychological disturbance. However, despite increasing usage, none of the present group have been implicated in joint damage in children, which had been a major concern following reports of this effect in juvenile animals in chronic toxicity studies. Furthermore, intravenous formulations appear to have no associated increase in toxicity. Crystalluria with associated renal damage, originally thought likely to limit intravenous dosage, has not proved to be a problem in humans. Clinically significant interactions may occur but, as with those involving various NSAIDs and potentially leading to convulsions, they have been defined and are thus avoidable. Postmarketing surveillance studies and prescription event monitoring have largely confirmed the limited adverse reaction profile defined during clinical trials. However, some unexpected reactions have appeared after launch, most notably the episodes of haemolysis, renal failure and hypoglycaemia which led to the withdrawal of temafloxacin. These effects have not been observed with other fluoroquinolones. However, severe tendinitis appears to be a group effect, albeit rare, and anaphylactoid reactions have been reported with several of the fluoroquinolone group, often in AIDS patients. The new fluoroquinolones are essentially a well tolerated group of antibacterials, the benefits of which clearly outweigh their disadvantages in a wide range of indications. Clinical efficacy has been a larger determinant of which members have succeeded in the marketplace than potential toxicity. However, the lesser potential for adverse effects of some of the class, e.g. norfloxacin, ofloxacin and ciprofloxacin, has undoubtedly led to their more widespread use. For others, e.g. enoxacin, limited clinical utility and a perception of increased toxicity have resulted in sidelining. There remains the potential for development of safer and yet more active fluoroquinolones via chemical manipulation both of the nucleus and the side chain substituents.

Ofloxacin. A reappraisal of its antimicrobial activity, pharmacology and therapeutic use

Ofloxacin is a fluoroquinolone whose primary mechanism of action is inhibition of bacterial DNA gyrase. In vitro it has a broad spectrum of activity against aerobic Gram-negative and Gram-positive bacteria, although it is poorly active against anaerobes. Ofloxacin, unlike most other broad spectrum antibacterial drugs, can be administered orally as well as intravenously. Penetration into body tissues and fluids is highly efficient. Clinical trials with orally and intravenously administered ofloxacin have confirmed its potential for use in a wide range of infections, where it has generally proved as effective as standard treatments. Ofloxacin in well tolerated, and in comparison with other available fluoroquinolones is less likely to cause clinically relevant drug interactions. Ofloxacin thus offers a valuable oral treatment (with an option for intravenous administration if necessary) for use in a wide range of clinical infections, but with a particular advantage in more severe or chronic infections when recourse to parenteral broad spectrum agents would normally be required, thereby providing cost savings and additionally allowing outpatient treatment.