A novel HPLC method developed and validated for the detection and quantification of atorvastatin, fluvastatin, pitavastatin and pravastatin during transdermal delivery studies.

An HPLC method was developed and validated to quantify and identify several statins (atorvastatin, fluvastatin, pitavastatin and pravastatin) that were used during transdermal drug delivery. The method proved to be most effective with a Restek Ultra C18, 250 x 4.6 mm, 5 µm column, a flow rate of 1.0 ml/min, UV detection at 240 nm and injection volume of 10 µl. The mobile phase used was acetonitrile/Milli-Q® water with 0.1% orthophosphoric acid starting with 30% acetonitrile, which increased linearly to 70% (after 4 min) for up to 10 min and then re-equilibrated to start conditions. This HPLC method indicated linearity (correlation coefficient (R²) of 1) within the concentration range of 0.05-200.00 µg/ml and had an average recovery of 98-103%. Limit of detection (LOD) and limit of quantification (LOQ) showed that statins could still be identified at concentrations of 0.004-0.006 µg/ml with the exception of atorvastatin (quantifiable at 0.013-0.035 µg/ml). Specificity performed during method validation, confirmed that the method was suitable for accurate detection and quantification of the statins when included in the transdermal formulations with other excipients.

Determination of lovastatin, mevastatin, rosuvastatin and simvastatin with HPLC by means of gradient elution.

A novel HPLC method with UV detection was developed and validated in skin penetration (in vitro) studies to identify and quantify lovastatin, mevastatin, rosuvastatin and simvastatin. A Venusil XBP C18 (2), 150 x 4.6 mm, 5 µm column (Agela Technologies, Newark, DE) was used with gradient elution (start at 45 % acetonitrile and increase linearly to 90 % after 1 min; hold at 90 % until 6 min and then re-equilibrate at start conditions) and the mobile phase consisted of (A) Milli-Q ® water and 0.1% orthophosphoric acid, and (B) HPLC grade acetonitrile. The flow rate was set at 1 ml/min, 240 nm UV detection and an injection volume of 10 µl. Linearity was obtained over a range of 0.50-200.00 µg/ml and correlation coefficients ranging from 0.998-1.000 were obtained. Average recovery ranged from 95.9-100.6 %. The LOD and LOQ values obtained from the slope of a calibration curve and the standard deviation of the response ranged from 0.0138-0.0860 µg/ml and 0.0419-0.2615 µg/ml, respectively, where lovastatin and simvastatin could be detected at a concentration similar to the other statins, but could only be quantified at a higher concentration than the remaining statins. The specificity of the method was proved as accurate and quantification of statins was found, even within the incorporation of other compounds.

In vivo/in vitro pharmacokinetic and pharmacodynamic study of spray-dried poly-(dl-lactic-co-glycolic) acid nanoparticles encapsulating rifampicin and isoniazid.

Poly-(dl-lactic-co-glycolic) acid (PLGA) nanoparticles were prepared by a double emulsion solvent evaporation spray-drying technique and coated with polyethylene glycol (PEG 1% v/v). The PLGA nanoparticles had a small size (229±7.6 to 382±23.9nm), uniform size distribution and positive zeta potential (+12.45±4.53mV). In vitro/in vivo assays were performed to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) performance of these nanoparticles following nanoencapsulation of the anti-tuberculosis drugs rifampicin (RIF) and isoniazid (INH). The results demonstrated the potential for the reduction in protein binding of these drugs by protection in the polymer core. Furthermore, in vitro efficacy was demonstrated using Mycobacterium tuberculosis (M. tb.) (strain H37Rv). Sustained drug release over seven days were observed for these drugs following once-off oral administration in mice with subsequent drug distribution of up to 10 days in the liver and lungs for RIF and INH, respectively. It was concluded by these studies combined with our previous reports that spray-dried PLGA nanoparticles demonstrate potential for the improvement of tuberculosis chemotherapy by nanoencapsulation of anti-tuberculosis drugs.

Enhancement of nasal and intestinal calcitonin delivery by the novel Pheroid fatty acid based delivery system, and by N-trimethyl chitosan chloride.

Therapeutic peptides are highly potent and specific in their functions, but difficulties in their administration require parallel development of viable delivery systems to improve their bioavailability. In this study the potential of a novel lipid-based colloidal delivery system for improving the absorption of nasally and intestinally administered salmon calcitonin (sCT) was investigated. Two types of delivery vehicles based on Pheroid technology was prepared and characterized. Liposome-like bilayer vesicles had a mean diameter of 1.0 microm and microsponges were 1.6 microm. Doses of 10 IU/kg and 500 IU/kg bodyweight sCT were administered intranasally and intestinally to rats, respectively. The obtained absorption enhancement with Pheroid vesicles and Pheroid microsponges were also compared with the absorption enhancement obtained with N-trimethyl chitosan chloride (TMC). With the inclusion of 0.5% (w/v) TMC the maximum plasma concentration (C(max)) of sCT increased from 72.6+/-6.1 pg/ml to 478.5+/-6.1 pg/ml after nasal administration. Pheroid vesicles and Pheroid microsponges increased the C(max) values of sCT to 262.64+/-17.1 pg/ml and 202.66+/-28.6 pg/ml, respectively. The time to reach the maximum concentration (T(max)) was also significantly decreased from 35 min to approximately 14 min. Intestinal administration of Pheroid formulations increased the C(max) of sCT from 249.1+/-21.5 pg/ml to 386.2+/-45.5 and 432.1+/-18.9 pg/ml, respectively for Pheroid vesicles and Pheroid microsponges. TMC increased the C(max) of sCT to 738.9+/-277.1 pg/ml. TMC and Pheroid technology could offer the potential to significantly improve intranasal and intestinal absorption of sCT and reduce the variability in absorption.

DNA damage and repair detected by the comet assay in lymphocytes of african petrol attendants: a pilot study.

Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxic and carcinogenic effects. The single-cell gel electrophoresis assay (comet assay) is a method highly sensitive to DNA damage induced by environmental and occupational exposure to carcinogenic and mutagenic agents. The aim of this study was to evaluate the level of exposure of petrol attendants to petrol VOCs and also to determine their effect on DNA damage and repair in lymphocytes of African petrol attendants. The exposed group consisted of 20 subjects, randomly selected from three petrol stations. A control group of 20 unexposed subjects was also chosen and matched for age and smoking habits with the exposed group. Sorbent tubes were used to assess personal exposure of petrol attendants. The comet assay was used to investigate the basal DNA damage and repair capacity in isolated lymphocytes of petrol attendants and unexposed subjects. Blood samples were taken from the petrol attendants at the end of their 8-h working shift and also from the unexposed subjects. The petrol attendants were found to be exposed to levels of petrol VOCs lower than the South African occupational exposure limit for constituent chemicals. A significant relationship was found between the volume of petrol sold during the shift and the average concentrations of benzene, toluene and the total VOCs measured. However, relative humidity had a negative correlation with the average concentrations of benzene, toluene, xylene and the total VOCs. Significantly higher basal DNA damage was observed with the exposed group compared to the unexposed group. The period of exposure influenced the level of DNA damage and the calculated repair capacity. Smoking and age had a significant influence on the level of DNA damage. DNA repair capacity was delayed in smokers of both exposed and unexposed group.

Southern African scorpion toxins: an overview.

In southern Africa there are 130 species of scorpions and only a few species' venom have been investigated to date. This review gives an overview of the research done on the venom of southern African scorpions and the toxins and peptides identified up to date. It also aims to highlight the enormous potential that lies in this field of research. Southern African scorpion toxins include four long-chain Na(+)-channel toxins, four short-chain alpha-K(+)-channel toxins (alpha-KTx), three Ca(2+)-channel toxins and also an insect-selective peptide active on K(+) and Cl(-) channels. Three antimicrobial peptides have also been isolated and characterized. All of these peptides are diverse not only in function and target but also in the species they are isolated from.