Polysorbate toxicity in neonatal rats and mice

Tween® Preserves Enzyme Activity and Stability in PLGA Nanoparticles

Enzymes, as natural and potentially long-term treatment options, have become one of the most sought-after pharmaceutical molecules to be delivered with nanoparticles (NPs); however, their instability during formulation often leads to underwhelming results. Various molecules, including the Tween^® polysorbate series, have demonstrated enzyme activity protection but are often used uncontrolled without optimization. Here, poly(lactic-co-glycolic) acid (PLGA) NPs loaded with β-glucosidase (β-Glu) solutions containing Tween^® 20, 60, or 80 were compared. Mixing the enzyme with Tween^® pre-formulation had no effect on particle size or physical characteristics, but increased the amount of enzyme loaded. More importantly, NPs made with Tween^® 20:enzyme solutions maintained significantly higher enzyme activity. Therefore, Tween^® 20:enzyme solutions ranging from 60:1 to 2419:1 mol:mol were further analyzed. Isothermal titration calorimetry analysis demonstrated low affinity and unquantifiable binding between Tween^® 20 and β-Glu. Incorporating these solutions in NPs showed no effect on size, zeta potential, or morphology. The amount of enzyme and Tween^® 20 in the NPs was constant for all samples, but a trend towards higher activity with higher molar rapports of Tween^® 20:β-Glu was observed. Finally, a burst release from NPs in the first hour with Tween^®:β-Glu solutions was the same as free enzyme, but the enzyme remained active longer in solution. These results highlight the importance of stabilizers during NP formulation and how optimizing their use to stabilize an enzyme can help researchers design more efficient and effective enzyme loaded NPs.

Effect of bile on the oral absorption of halofantrine in polyethylene glycol 400 and polysorbate 80 formulations dosed to bile duct cannulated rats

Objectives

The aim of this study was to examine the effects of bile on the oral absorption of the poorly water-soluble compound, halofantrine, when administered to rats in vehicles consisting of the co-solvent polyethylene glycol 400 (PEG 400) alone or in mixtures with the surfactant polysorbate 80 (PS 80) (95 : 5; 85 : 15; 75 : 25 PEG 400 : PS 80).

Methods

Halofantrine (17.5 mg/kg) was administered to bile duct cannulated (BDC) and sham-operated rats in a fixed vehicle volume of 5 ml/kg.

Key findings

The bioavailability of halofantrine was significantly lower in BDC rats when dosed with 0–5% PS 80 in PEG 400 compared with BDC rats dosed with >15% PS 80. Increasing the concentration of PS 80 to 15–100% eliminated this difference. A possible explanation for the lower bioavailability of halofantrine in BDC rats when dosed in pure PEG 400 could be the dilution of the vehicle by intestinal fluids, decreased transit time and precipitation in the gastrointestinal tract upon dilution of PEG 400.

Conclusions

The addition of PS 80 to the formulation increased its solubilising power upon dilution and may have inhibited precipitation and substituted the absence of bile above a certain level. Adjusting the level of surfactant in drug formulations could therefore be used to minimise variability in the bioavailability from co-solvent systems based upon differences in bile concentration between individuals.

Challenges associated with the evaluation of veterinary product bioequivalence: an AAVPT perspective

The Generic Animal Drug Patent Term Restoration Act (GADPTRA) enacted in 1988 provided the same benefits to animal drug products that were granted to human generic products. It has been over 13 years since the GADPTRA was enacted, and veterinary drug sponsors and regulators have gained enormous insight and experience into some of the unique challenges associated with the determination of product bioequivalence for veterinary dosage forms. Moreover, advances in information and technology have opened both new issues that must be addressed and new mechanisms for demonstrating product bioequivalence. While many aspects of the existing Center for Veterinary Medicine Bioequivalence Guidance continue to provide invaluable guidance to the animal drug industry, there are also aspects of this guidance that are being called into question. Therefore, during the 2001 annual meeting of the American Academy of Veterinary Pharmacology and Therapeutics, participants were asked to address issues and concerns associated with the evaluation of veterinary product bioequivalence. This manuscript provides a summary of the concerns and discussions that transpired.

Quantitative determination of polysorbate 20 in nasal pharmaceutical preparations by high-performance liquid chromatography

A specific reverse-phase HPLC method has been developed for the quantitative determination of polysorbate 20 in various compositions of nasal solutions. This method is based on the acidic hydrolysis of the sorbitan laurate ester followed by the HPLC determination of the free lauric acid. Using this method, polysorbate 20 can effectively be separated and quantitatively determined in matrices containing a wide variety of preservatives, surfactants, and viscosity agents. Sample preparation involves a one-step hydrolysis with sulfuric acid and then a dilution with acetonitrile, prior to injection. The sample is analyzed on a 5-microm octadecylsilane reverse-phase column with a mobile phase of acetonitrile: 0.025 M aqueous di-Sodium hydrogen phosphate, pH = 2.8 (75:25). The column effluent is monitored by UV detection at 210 nm. The validity of the method has been verified with specificity, linearity, recovery, method- and system precisions data. The method is linear for polysorbate 20 from 2.5 to 125 mg ml(-1) range. The limit of detection and limit of quantitation are 0.41 and 0.61 mg ml(-1), respectively.