Intravenous-to-oral switch in antimicrobial therapy: clinical pharmacology considerations and perspectives

Clinical pharmacological considerations in an early intravenous to oral antibiotic switch: are barriers real or simply perceived?

BACKGROUND

Traditionally, there has been a common belief that ongoing i.v. antibiotic therapy is superior to an early i.v. to oral switch, especially for severe infections. However, this may be at least partly based on early observations rather than robust, high-quality data and contemporary clinical studies. It is important to examine whether these traditional views align with clinical pharmacological considerations, or conversely, if these considerations may support the broader application of an early i.v. to oral switch under appropriate circumstances.

OBJECTIVES

To examine the rationale for an early i.v. to oral antibiotic switch in the context of clinical pharmacokinetic and pharmacodynamic principles and to discuss whether commonly encountered pharmacological barriers are real or simply perceived.

SOURCES

We conducted PubMed searches on barriers and clinicians' perceptions about an early i.v. to oral switch, clinical studies comparing switching with i.v.-only dosing, and pharmacological factors affecting oral antimicrobials.

CONTENT

We focused on general pharmacological and clinical pharmacokinetic and pharmacodynamic principles and considerations that are relevant when clinicians ponder whether to switch from i.v. to oral antimicrobial dosing. The main focus of this review was on antibiotics. The discussion of the general principles is accompanied by specific examples from the literature.

IMPLICATIONS

Clinical pharmacological considerations and an imposing and increasing number of clinical studies, including randomized clinical trials, support an early i.v. to oral switch for the treatment of a number of infection types, under appropriate circumstances. We hope that the information provided here will add to calls for a critical examination of the role of i.v. to oral switching for many infections that are currently treated almost exclusively with i.v.-only therapy, and that it will inform health policy and guideline development by infectious diseases organizations.

A concise review of bioanalytical methods of small molecule immuno-oncology drugs in cancer therapy

Immuno-oncology (IO) is an emerging option to treat cancer malignancies. In the last two years, IO has accounted for more than 90% of the new active drugs in various therapeutic indications of oncology drug development. Bioanalytical methods used for the quantitation of various IO small molecule drugs have been summarized in this review. The most commonly used are HPLC and LC-MS/MS methods. Determination of IO drugs from biological matrices involves drug extraction from the biological matrix, which is mostly achieved by simple protein precipitation, liquid-liquid extraction and solid-phase extraction. Subsequently, quantitation is usually achieved by LC-MS/MS, but HPLC-UV has also been employed. The bioanalytical methods reported for each drug are briefly discussed and tabulated for easy access. Our review indicates that LC-MS/MS is a versatile and reliable tool for the sensitive, rapid and robust quantitation of IO drugs.

Relevance of preclinical rodent pharmacokinetics in the selection of a companion antibiotic for combining with beta-lactamase inhibitor

Recent approvals of beta-lactamase inhibitor (BLI) drug in combination with cephalosporins/penems have provided the right impetus for novel BLIs. One important research question, hitherto not addressed, is pertaining to the relevance of preclinical pharmacokinetics for pairing the antibiotic with existing/novel BLI.Two BLI combination drugs: (a) approved (i.e. ceftazidime/avibactam); (b) clinical development (i.e. cefepime/zidebactam) were explored to provide insights to address the research question.Individual intravenous dosing of ceftazidime, avibactam, cefepime and zidebactam was done at 1 mg/kg by intravenous route in Balb/c mice and Wistar rats. Serial blood samples were collected and analysed by LC-MS/MS method.Examination of the ratios of pharmacokinetic parameters (CL, V_SS and T_1/2) for individual drugs in combinations (for instance, CL (ceftazidime)/CL (avibactam); CL (cefepime)/CL (zidebactam)) suggested that the pharmacokinetic data gathered in rats were generally within 0.5- to 2-fold; but mouse data revealed larger disparity for V_SS (0.11- to 8.25-fold) or CL (0.49- to 4.03-fold).The observed ratio for CL/V_SS observed in rats agreed with corresponding human ratios for the pairwise comparison of the individual drugs in the combinations.Retrospectively, current pharmacokinetic findings suggest rat pharmacokinetic data may aid the combination of BLI with an appropriate antibiotic.