Evaluation of the viability of Lactobacillus spp. in different dosage forms

Tese de doutoramento, Farmácia (Tecnologia Farmacêutica), Universidade de Lisboa, Faculdade de Farmácia, 2009.The Thesis aimed to provide evidence on the incorporation of Lactobacillus spp. into different dosage forms keeping their viability and antibacterial activity. In order to achieve this aim, the survival of probiotic microorganisms in freeze-dried powders, tablets, pellets, calcium alginate beads and films has been investigated. Two strategies were used: a) direct incorporation of bacterial suspensions into pellets, sodium alginate beads and films and b) incorporation of freeze-dried bacteria into tabletting excipients to produce tablets. The vegetative forms of Lactobacillus plantarum, Lactobacillus rhamnosus strain GG, Lactobacillus lactis and Lactobacillus bulgaricus and a spore form of Bacillus subtilis were considered as model bacterial strains. The different bacteria chosen have shown different viabilities to formulation and processing with decreasing viability as follows: B. subtilis, L. plantarum, L. rhamnosus GG and L. bulgaricus. The process of drying was critical for obtaining a high survival rate. Freeze drying allowed high viability ( 1 log unit decrease) contrary to air drying observed during the process of extrusion-spheronisation and subsequent fluid bed drying. Nutrients and cryoprotectants (skim milk, glycerol, mannose, calcium alginate) should be present at early stages of processing, before de-hydration, to promote the stabilization of bacteria. Pressure, whether applied during extrusion or compaction, reduced bacterial viable counts. Tabletting of freeze-dried bacteria alone or together with inulin had a less deleterious effect on bacterial viability (1-2 log unit decrease during compaction followed by 1-2 log unit during storage) compared to pelletisation (in some cases 3 log units during processing, reaching minimum of detection in 1 to 4 months). However, tabletting of freeze-dried bacteria together with microcrystalline cellulose had a detrimental effect on bacterial viability comparable to pelletisation. Coating of either tablets or pellets was considered less deleterious compared to tabletting and pelletisation. Coating caused an initial decrease of viability (<1 log unit) but did not affect the survival rates further during storage. The highest survival rates of probiotic bacteria were obtained by the technique of immobilization into calcium alginate beads and films: 1 log unit decrease during freeze-drying of beads and films and <1 log unit during storage. The antibacterial activity of lactobacilli against multi-resistant clinical isolates (upon their preservation in calcium alginate beads and films) has been observed. Lactobacilli, particularly whole cultures, at high cell concentrations (108 cfu/ml) were inhibitory active. The antibacterial activity of the lactobacilli remained stable during processing and storage provided the viability was preserved (L. plantarum, LGG and L. lactis). Immobilized lactobacilli caused a 5 to 6 log unit reduction of a VIM-2-metalo- - lactamase producing Pseudomonas aeruginosa in rat burns: from 107-108 to 102 P. aeruginosa / g of skin in 8 hours. It has been demonstrated the successful production of various dosage forms for the delivery of viable lactobacilli with antibacterial activity against multi-resistant bacteria. The developed dosage forms could contribute to the use of lactobacilli as an alternative in topical prevention of burn wound infections.O objectivo desta tese é demonstrar a incorporação de Lactobacillus spp. em diferentes formas farmacêuticas mantendo a sua viabilidade e actividade antibacteriana. Para obter este objectivo, foi investigada a sobrevivência dos microrganismos probióticos em pós liofilizados, comprimidos, pellets, beads e filmes de alginato de cálcio. Foram usadas duas estratégias: a) incorporação directa de suspensões bacterianas para produzir pellets, beads e filmes de alginato de cálcio e b) incorporação de bactérias liofilizadas em excipientes para produzir comprimidos. As formas vegetativas Lactobacillus plantarum, Lactobacillus rhamnosus estirpe GG, Lactobacillus lactis e Lactobacillus bulgaricus e Bacillus subtilis em forma de esporos foram considerados como modelo de estirpe bacteriana. As diferentes bactérias seleccionadas demonstraram diferentes viabilidades à formulação e produção, com viabilidade decrescente na seguinte sequência: B. subtilis, L. plantarum, L. rhamnosus GG e L. bulgaricus. O processo de secagem foi crítico para a obtenção de altas taxas de sobrevivência. Liofilização permitiu alta viabilidade ( 1 unidade logarítmica de decréscimo) contrariamente à secagem ao ar observada durante o processo de extrusão e esferonização e subsequente secagem por leito fluido. Nutrientes e crioprotectores (skim milk, glicerol, manose, alginato de cálcio) devem estar presentes nas fases iniciais do processo, antes da desidratação, para promover a estabilização das bactérias. A pressão, aplicada durante a extrusão ou compactação, reduziu a viabilidade. A produção de comprimidos de bactérias liofilizadas com ou sem inulina teve um menor efeito deletério na viabilidade (1 a 2 unidades logarítmicas de decréscimo durante a compactação seguida por 1 a 2 unidades logarítmicas de decréscimo durante armazenamento) quando comparada com a peletização (3 unidades logarítmicas de decréscimo nalguns casos, atingindo a detecção mínima ao fim de 1 a 4 meses). No entanto, a produção de comprimidos de bactérias liofilizadas em conjunto com celulose microcristalina teve um efeito deletério na viabilidade comparável ao da peletização. O revestimento de comprimidos ou pellets foi considerado menos deletério do que a produção de comprimidos ou peletização. O revestimento causou um decréscimo inicial de viabilidade (<1 unidade logarítmica) mas não afectou as taxes de sobrevivência durante o armazenamento. As mais altas taxas de sobrevivência de bactérias probióticas foram obtidas com a técnica de imobilização em beads e filmes de alginato de cálcio: 1 unidade logarítmica de decréscimo durante liofilização de beads e filmes e <1 unidade logarítmica durante armazenamento. Foi observada a actividade antibacteriana de lactobacilli contra isolados clínicos multi-resistentes (após a sua preservação em beads e filmes de alginato de cálcio). Observou-se que lactobacilli, particularmente as culturas inteiras, em altas concentrações celulares (108 cfu/ml) provocaram inibição. A actividade antibacteriana dos lactobacilli permaneceu estável durante o processamento e armazenamento desde que a viabilidade fosse preservada (L. plantarum, LGG e L. lactis). Lactobacilli imobilizados causaram um decréscimo de 5 a 6 unidades logarítmicas de VIM-2- metalo- -lactamase produzindo Pseudomonas aeruginosa em queimaduras de ratos: de 107-108 a 102 P. aeruginosa / g de pele em 8 horas. Foi demonstrada a produção com sucesso de várias formas farmacêuticas para a administração de lactobacilli viáveis com actividade inibitória contra bactérias multiresistentes. As formas de dosagem desenvolvidas podem contribuir para o uso tópico de lactobacilli como alternativa à prevenção de infecções em queimaduras.Fundação para a Ciência e a Tecnologia, Portugal (FCT),(SFRH/BD/17193/2004

Effect of different excipients and processing conditions on casein micellar formulation for children

Poster presented at the AAPS Annual Meeting and Exposition (American Association of Pharmaceutical Scientists). October 25-29, 2015, Orlando (FL), USA"Purpose: Investigation of the potential of casein micellar formulations as drug vehicles in pediatrics."Fundação para a Ciência e a Tecnologia (PTDC/DTP-FTO/1057/2012

Evaluation of the ability of powdered milk to produce mini-tablets to deliver paracetamol in pediatrics

Paper presented at the 7th International Granulation Workshop. 1-3 July 2015, University of Sheffield, UK"This work aims to evaluate the usefulness of powdered milk as a vehicle of drugs for direct compression into mini-tablets specifically designed for the pediatric population. A 23 full factorial design was carried out to identify the effect of selected variables and their interactions (paracetamol to milk ratio, fraction of disintegrant and compression force), on selected responses (weight variation, thickness and tensile strength of minitablets and dissolution time of paracetamol) of the mini-tablets. Tablets were manufactured according to a matrix design resulting in eight combinations of four different tableting formulations compacted at two distinct forces. Each batch of tablets was evaluated for thickness (n=6), uniformity of weight (n=20), diametric crushing strength and tensile strength (σ) (n=6) and dissolution testing (n=12). A stepwise multiple linear regression was used to identify and quantify the relationships between each response and the variables studied and their interactions. Results were analyzed by ANOVA to identify the significant variables and variable interactions responsible for the effects observed.The increase on milk fraction in the formulation improved the compressibility of paracetamol with a decrease on weight variation. Thinner and harder compacts with slower paracetamol releases were also obtained. These observations were not surprising if powdered milk composition is taken into consideration: milk proteins, lactose (widely used as diluent) and lipids (often used as binders, lubricants and taste masking agents), which individually or in combination contribute to easier the production of tablets. A marked decrease on the dissolution time was observed as sodium croscarmellose was added to the milk rich formulations, as anticipated. The increase of the compression force was reflected by the production of thinner compacts with slightly higher tensile strengths but little effect on the dissolution median time. At high forces it was often observed a higher crushing strength and an increase of the importance of particle deformation in disintegration time.The study has proved the viability of using powdered milk on the production of minitablets to the delivery of drugs. The experimental design and statistical analysis enabled the identification of the most significant variables and their interactions affecting the properties of the mini-tablets, particularly the milk/paracetamol ratio which proved to be critical for the proprieties of the final product."Fundação para a Ciência e Tecnologia (FCT

Evaluation of the Viability of Lactobacillus spp. After the Production of Different Solid Dosage Forms

The work aims to provide evidence on the viability of Lactobacillus spp. and a spore form of Bacillus subtilis from nonprocessed bacteria to coated dosage forms (i.e., mini-tablets, pellets, and their coated forms). Lactobacillus spp. were cultivated overnight in MRS broth (10(9) cfu/mL) and B. subtilis spores were produced on plate count agar (107 cfu/mL) for 2 weeks. Bacteria and spores were freeze-dried in skim milk enriched with glycerol. The cakes were further processed into tablets (2.5 mm diameter) by direct compression with or without microcrystalline cellulose and inulin. Pellets (1-1.4 mm diameter) were produced by extrusion-spheronization of bacterial and spore suspensions with microcrystalline cellulose, lactose, inulin, and skim milk. Both tablets and pellets were film coated. The properties of the dosage forms, particularly the bacterial viability, were evaluated immediately after production and throughout storage for 6 months at 4 degrees C. The study has shown that for an adequate stabilization of the bacteria a protective matrix (e.g., skim milk) and cryoprotectors (e.g., glycerol) must be present at early stages of bacterial de-hydration. Tabletting had a less deleterious effect (2 log units) on bacteria when compared to pelletization (in some cases 3 log units). Enteric coating (15%, w/w) of either tablets or pellets did not affect the viability of the bacteria. (C) 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3329-3339, 2009. - Fundacao para a Ciencia e a Tecnologia (FCT), Portugal [SFRH/BD/17193/2004]. - This work was supported by a research grant from Fundacao para a Ciencia e a Tecnologia (FCT), Portugal (SFRH/BD/17193/2004) and by material resources made available by Associacao Desenvolvimento Ensino Investigacao Microbiologia (ADEIM)