Antibiotic PK/PD

HFBRs: An advancement for pharmacokinetics (PK), pharmacodynamics (PD) and in-vitro toxicology

A hollow fiber bioreactor is a superior tool for examining the effects of a certain drug dose on cells

The emergence of antibiotic resistance represents a clear threat to global health. Antibiotic drug effect can be both time and concentration dependent and static models cannot provide data on the most effective dosing profiles nor reveal the emergence of drug resistance over time. There have not been effective tools for examining the effects of both time and concentration of an antibiotic in an in vitro model that can mimic human bio-availability and drug kinetic. The emergence of drug resistant strains of pathogenic bacteria mandates that new tools be available for the study of antibiotics.

To meet these requirements the two-compartment model was developed. Our hollow fiber two compartment model provides you the advantage over one compartment models, static models and animal models. This illustration shows the hollow fiber two compartment model. Test organisms are retained in the hollow fiber cartridge. The central reservoir is continuously re-circulating the nutrient broth. Drug is added to the central reservoir and the elimination kinetics are controlled by the addition of diluent to the central reservoir. The volume in the central reservoir is kept constant.

Current assays for the determination of antibiotic efficacy are also not able to examine the potential for the development of resistance since antibiotic resistance develops over time. A dynamic model controlling drug concentration over time precisely mimicking human pk/pd would bridge the gap between static assays, animal models and clinical trials. A time related assay capable of examining the effects of antibiotic pharmacokinetics on a population of organisms large enough to reveal the emergence of resistance is also required.

The design of the two compartment model is quite similar to the one compartment model except that the organism to be tested is confined within the ECS, physically separated from the central reservoir by the semi-permeable membrane. The concentration of the drug in the central reservoir equilibrates rapidly with the medium in the ECS containing the organisms. The volume of the central reservoir can be adjusted to permit rapid changes in drug concentration. Hollow fiber cartridges offer the advantages of having an extremely high surface area to volume ratio, in excess of 150 cm² per milliliter of volume, providing rapid and uniform distribution of the drug within the ECS. Several different types of hollow fiber polymers are commercially available to allow for compatibility with drugs of different chemistries.

Cross section of a hollow fiber cartridge. The test organism is retained in the small volume outside the fiber while nutrient broth and drug circulate through the insides of the fiber. Small molecules such as drugs can freely cross the fiber along with nutrients and waste products, while bacteria and cells cannot cross the fiber.

A CLOSER LOOK AT HOW TO SET UP A CARTRIDGE IN A BIOREACTOR

FiberCell Systems cartridges are supplied assembled with the flow path ready to use. They are pre-sterilized and double bagged with instructions provided. Watch the video instruction for a detailed guide to set up a cartridge.

Advantages of Hollow Fiber vs. One Compartment Model

Bacterial load remains constant
Biohazardous organisms are safely contained
Both absorption and elimination curves can be modeled
Rapid half lifes can be modeled

Advantages of Hollow Fiber vs. static models

Target bacteria are contained within a very small volume so the drug can equilibrate rapidly within the compartment
Representative samples can be taken easily without significantly affecting the bacteria population
Drug resistant, highly pathogenic, and highly biohazardous organisms are safely contained in a sealed environment
Large numbers of organisms can be tested in one experiment
Both absorption and elimination kinetics of the drug being testing can be precisely and independently controlled
Kinetics of multiple drugs can also be controlled so drug/drug interactions and combination therapies can readily be examined

Advantages of Hollow Fiber vs. animal models

High bacterial and viral loads can be tested, dosage profiles that result in resistance will more likely be revealed
Absorption, excretion, and metabolic profiles can be more closely modeled on the human half-life
Not all animals can be infected with the organism of interest
Extreme doses can be modeled
Combination therapies can be easily controlled and tested
No animal testing protocols, restrictions
Less expensive
Closed, bio-safe system for pathogens
Easier to test multiple pathogens with the same drug
Larger N per experiment (cartridges in series)
Bacteria, viruses, cancer, and parasites can be tested
Dosage and metabolic profiles can be more precisely controlled

THE HOLLOW FIBER INFECTION MODEL (HFIM)

Hollow fiber technology offers higher levels of reproducible control of both concentration and time of drug exposure in complex growth, infection, treatment, and sampling regimens. This system permits more realistic simulation of in-vivo drug effects in a dynamically controlled system providing data that more accurately reflects biological responses.

They are fully disposable and provide a biosafe environment for the potential testing of drug resistant, weaponized, or genetically modified organisms. The two-compartment model can be a cost effective supplement to the evaluation of clinical efficacy both for existing antibiotics and in the development process for new antibiotics as part of the submission process for FDA approval.

A HFS Pretest study is used to run drug alone to determine drug compatibility with the system.

If you need to test the effects of two drugs at the same time on the same test cells, it's possible with FiberCell 2 drug HFBR model.

The 5-Port Reservoir Cap is an important element of the HFIM

Accurate usage of reservoir is important in ensuring results. An example of a 5-port reservoir cap demonstrating fluid flow is shown below.

The vent should not reach the liquid in the reservoir, and the “diluent out” tube should be set to the level that should result in the desired constant volume in the central reservoir.

PROPER SETUP TECHNIQUE

MINI-WEBINAR: The Hollow Fiber Infection Model and Antibiotic Pk/Pd [VIDEO]
Hollow Fiber System of Tuberculosis Laboratory Manual [PDF]
Product List [XLSX]
Pump Settings for in-vitro Hollow-fiber Experiments

Web Application for Pump Settings

An R-shiny web application, was developed to facilitate the conversion of in-vivo pharmacokinetic profiles into in-vitro pump settings in the hollow fiber system.

Click here to use it: https://pkpdia.shinyapps.io/hfs_app/

Source: Mimicking in-vivo exposures to drug combinations in-vitro: antituberculosis drugs in lung lesions and the hollow fiber model of infection: Kloprogge, F. et al, www.nature.com/scientificreports 13 Sep 2019 [open access]

REFERENCES

Useful links

Suggested Ordering for PK/PD

Suggested Ordering for Antibiotic PK/PD:

Bioreactor
P3202	The FiberCell^® Systems Duet more info
Cartridges
Catalog No.	Size	Surface Area	Fiber Type	Packing Density	ECS Vol	MWCO 50%	Max. Cell#
C2025D	Small	450 cm²	High flux PS	50%	3.2 mL	20 kD	10⁸	more info
C2011	Medium	4000 cm²	High flux PS	50%	15 mL	20 kD	10⁹	more info
C8008	Medium	2500 cm²	Cellulosic	40%		5 kD	5x10e⁸	more info
Reservoir Caps
A1006	38 mm Reservoir Cap more info
A1007	5 port 38mm Reservoir Cap more info

Click here for our US list pricing for 2023. We offer tiered discounted pricing for quantity purchases of our products, 10-25 units, 25+ units, and 50+ units. Please enquire for details. We recommend the most appropriate products for your applications so please feel free to email or phone us to discuss your application and provide you with a quote at info@fibercellsystems.com, 301-471-1269, 240-440-2662. We can accept credit cards and purchase orders from accredited institutions.

1. The Hollow Fiber Infection Model, Principles and Practice

Emerging antibiotic resistance presents a serious global health threat and has been identified as one of the three greatest threats to human health. Antibiotic discovery and development require static susceptibility testing to screen compounds, in vitro pharmacodynamics/pharmacokinetic (PK/PD) studies to model drug dynamics and efficacy, and testing in animal models to provide critical information prior to the clinical evaluation of new antibiotics. Read paper here.

2. EMA endorsement

The EMA has endorsed FiberCell’s in-vitro hollow fiber system model of tuberculosis (HSF-TB) for use in drug development. See endorsement here.

3. The Hollow Fiber Infection Model for Antimicrobial Pharmacodynamics and Pharmacokinetics

PK/PD assays are one of the first steps in determining the potential utility of a specific compound for antimicrobial activity. The Hollow Fiber Infection Model can provide useful data for antibiotic development and dosing. Hollow fiber technology offers higher levels of reproducible control of both concentration and time of drug exposure in complex growth, infection, treatment, and sampling regimens. Read paper here.

WE ARE HERE TO HELP

For detailed information on producing recombinant proteins using HFBRs in your laboratory, contact us or request for a quote.