Physical compatibility of lipid emulsions and intravenous medications used in neonatal intensive care settings

OBJECTIVE

The purpose of this study was to investigate the physical compatibility of intravenous lipid emulsions with parenteral medications used in neonatal intensive care.

METHODS

Lipid emulsion and drug solutions were combined 1:1 in glass vials, inspected for physical incompatibility at 0, 1 and 2 hours, and assessed on the basis of lipid droplet size at 0 and 2 hours after mixing. Intravenous fluid controls (Water for Injection, sodium chloride 0.9% w/v, glucose 5% w/v), positive controls (gentamicin, albumin), negative controls (metronidazole, paracetamol, vancomycin) and 21 previously untested drug combinations were evaluated.

RESULTS

No phase separation, change in colour, gas production or other visible anomaly was observed. The between-run mean droplet diameter (MDD) for SMOFlipid20% alone (0.301±0.008 µm) was comparable to the lipid emulsion/intravenous fluid and lipid emulsion/drug solution combinations. In addition to gentamicin and albumin, caffeine citrate (20 mg/mL) was shown to be incompatible with the lipid emulsion. All other lipid:drug combinations were compatible, based on the MDD data.

CONCLUSION

Intravenous lipid emulsions were found to be compatible with 20 parenteral medications, including antimicrobial agents, inotropes, anti-inflammatory drugs and caffeine base, in simulated Y-site conditions. The lipid emulsion was incompatible with caffeine citrate injection.

Stability of Pentoxifylline Injection: Application to Neonatal/Pediatric Care Setting

Pentoxifylline (PTX) is administered as 6- or 12-hour intravenous infusions in the treatment of sepsis or necrotizing enterocolitis in neonates; however, there is a paucity of formal stability data for PTX in the end-use solution. We investigated PTX stability in the simulated clinical conditions of neonatal intensive care, where PTX injection is diluted to 5 mg/mL and administered via syringe pump. A stability-indicating high performance liquid chromatography (HPLC) assay was established for PTX. The clinical simulation stability study comprised PTX 5 mg/mL in 20 mL syringes and was conducted at three temperatures, all protected from light: refrigerator (4°C); room temperature (22°C) and incubator/humidicrib (35°C). PTX stability also was evaluated at room temperature and exposed to light. Samples were drawn at pre-determined times over a 10 day period and stored frozen (-80°C) until assayed by HPLC. A single exponential equation was fitted to the concentration-time data to determine PTX stability. Forced degradation studies confirmed that PTX was stable at elevated temperature (up to 45°C), exposed to light and under acidic stress for up to 10 days, but subject to degradation under alkali and oxidative stress. PTX injection 5 mg/mL in 0.9% w/v sodium chloride or 5% w/v glucose was found to be stable when protected from light at 22°C and 35°C, and exposed to light at 22°C for at least 7 days. These data provide clinically relevant evidence that PTX injection is stable in the end-use, ICU/incubator clinical conditions for at least 24 hours.

Quality of benzathine penicillin G: A multinational cross-sectional study

Benzathine penicillin G (BPG) is used as first-line treatment for most forms of syphilis and as secondary prophylaxis against rheumatic heart disease (RHD). Perceptions that poor quality of BPG is linked to reported adverse effects and therapeutic failure may impact syphilis and RHD control programs. Clinical networks and web-based advertising were used to obtain vials of BPG from a wide range of countries. The quality of BPG was assessed using a high performance liquid chromatography assay capable of detecting relevant impurities and degradation products. Tests for water content, presence of heavy metals and physical characteristics of BPG, including particle size analysis and optical microscopy, also were conducted. Thirty-five batches of BPG were sourced from 16 countries across 4 WHO regions. All batches passed the US Pharmacopeia requirements for BPG injection (content), with no evidence of breakdown products or other detected contaminants. Water content and heavy metal analysis (n = 11) indicated adherence to regulatory standards and Good Manufacturing Practice. Particle size analysis (n = 20) found two batches with aggregated particles (>400 µm) that were dispersed following sonication. Current batches of BPG were of satisfactory pharmaceutical quality but aggregated particles were found in a modest proportion of samples. Future studies should focus on the physical characteristics of BPG which may contribute to variations in plasma penicillin concentrations an observed needle blockages in clinical practice. Pharmacopeial monographs could be revised to include standards on particle size and crystal morphology of BPG.

Ergometrine stability in postpartum haemorrhage kits: Does temperature and light matter?

BACKGROUND

Postpartum haemorrhage (PPH) kits containing uterotonics are used on obstetric units for the timely management of PPH. Visible discolouration of ergometrine and ergometrine-oxytocin injections was observed in PPH kits stored in medical refrigerators on the obstetric unit at our hospital.

AIM

To investigate the stability of ergometrine and ergometrine-oxytocin injections in PPH kits under simulated clinical storage conditions and to determine the potency of ampoules quarantined from PPH kits on our obstetric unit.

MATERIAL AND METHODS

Ergometrine and ergometrine-oxytocin injection ampoules were stored exposed to and protected from light at 4°C and room temperature (25°C) for up to three months, and assayed by high-performance liquid chromatography. Stability was based on the time for the ergometrine or oxytocin concentration to fall to 90% of the original concentration (t₉₀ ). The potency of quarantined discoloured ampoules also was determined.

RESULTS

Ergometrine was stable at both temperatures for >6 months, when stored protected from light in simulated clinical conditions. When exposed to light, ergometrine was stable for approximately 4 days at 25°C and 10 days at 4°C. Discoloured ergometrine and ergometrine-oxytocin injection ampoules were found to be <90% of the nominal concentration.

CONCLUSION

Stability of ergometrine in PPH kits is largely unaffected by temperature fluctuations (at 4°C and 25°C) over 6 months when protected from light. Ergometrine and ergometrine-oxytocin ampoules should be inspected prior to use and any discoloured ampoules discarded.

Physical compatibility of pentoxifylline and intravenous medications

OBJECTIVE

To investigate the physical and chemical compatibility of pentoxifylline (PTX) with a wide range of parenteral medications used in the neonatal intensive care setting.

DESIGN

PTX and drug solutions were combined in glass phials and inspected visually for physical incompatibility. The chemical compatibility was evaluated on the basis of PTX concentrations.

RESULTS

Precipitation, colour change or turbidity was not visible in any of the test mixtures, indicating no observed physical incompatibility or apparent risk of blockage in narrow-bore intravenous tubing. The PTX concentration was approximately 2.5% and 4.5% lower when combined with dopamine and amoxicillin, respectively. The PTX concentration ratios for all other combinations were in the range of 99%-102%.

CONCLUSION

In simulated Y-site conditions, physical compatibility testing of PTX and 30 parenteral medications revealed no evidence of precipitation. Based on PTX concentration tests, it could be prudent to avoid mixing PTX with dopamine or amoxicillin.

The Interactions of P-Glycoprotein with Antimalarial Drugs, Including Substrate Affinity, Inhibition and Regulation

The combination of passive drug permeability, affinity for uptake and efflux transporters as well as gastrointestinal metabolism defines net drug absorption. Efflux mechanisms are often overlooked when examining the absorption phase of drug bioavailability. Knowing the affinity of antimalarials for efflux transporters such as P-glycoprotein (P-gp) may assist in the determination of drug absorption and pharmacokinetic drug interactions during oral absorption in drug combination therapies. Concurrent administration of P-gp inhibitors and P-gp substrate drugs may also result in alterations in the bioavailability of some antimalarials. In-vitro Caco-2 cell monolayers were used here as a model for potential drug absorption related problems and P-gp mediated transport of drugs. Artemisone had the highest permeability at around 50 x 10(-6) cm/sec, followed by amodiaquine around 20 x 10(-6) cm/sec; both mefloquine and artesunate were around 10 x 10(-6) cm/sec. Methylene blue was between 2 and 6 x 10(-6) cm/sec depending on the direction of transport. This 3 fold difference was able to be halved by use of P-gp inhibition. MRP inhibition also assisted the consolidation of the methylene blue transport. Mefloquine was shown to be a P-gp inhibitor affecting our P-gp substrate, Rhodamine 123, although none of the other drugs impacted upon rhodamine123 transport rates. In conclusion, mefloquine is a P-gp inhibitor and methylene blue is a partial substrate; methylene blue may have increased absorption if co-administered with such P-gp inhibitors. An upregulation of P-gp was observed when artemisone and dihydroartemisinin were co-incubated with mefloquine and amodiaquine.

The influence of passage number for Caco2 cell models when evaluating P-gp mediated drug transport

Caco2 cells are a human adenocarcinoma cell line that forms tight junctions and are widely used to examine bidirectional drug transport as well as P-glycoprotein mediated efflux. Unfortunately Caco2 cell lines can be very heterogeneous in nature. Our aim was to improve the Caco2 cell model for determination of P-glycoprotein mediated drug transport. Young passage Caco2 from ATCC had inadequate expression of P-glycoprotein, therefore three approaches were adopted to upregulate Caco2 P-glycoprotein expression to mimic that in vivo; a) incubation of mature Caco2 monolayer with rifampicin, b) prolonged exposure of Caco2 cells to vinblastine (generating the Caco2 VIN line), and c) splitting cells every 7 to 9 days until late passage numbers (over P80) were available. Upon development of the models, P-gp expression and activity was determined using western blotting and bidirectional transport studies of rhodamine123. All four models exhibited P-gp mediated efflux transport for rhodamine123. Incubation with rifampicin did not alter bidirectional transport compared to passage 44 cells. Increased passage number altered P-glycoprotein expression and the efflux ratio increased to 4.7 for passage 80 from 1.4 of passage 44. The highest basolateral to apical transport was observed for both passage 89 Caco2 and the Caco2 VIN model with an efflux ratio of 13 to 14. Western blot images confirmed the increased P-glycoprotein expression of late passage and Caco2 VIN. Caco2 cells are not ready for P-gp related research when first acquired from ATCC (Passage 18). Late passage Caco2 cell monolayers or Caco2 VIN models are needed to determine P-gp mediated efflux transport.

Medicine prices, availability and affordability in Sri Lanka

BACKGROUND

No pricing formula has been implemented from November 2002 to date in Sri Lanka. Therefore, we initiated a study in 2003 to determine the prices, availability and affordability of medicines in the private sector of Sri Lanka in the absence of a price control.

MATERIALS AND METHODS

The World Health Organization/Health Action International methodology was used. The study was conducted in retail pharmacies (Rajya Osu Sala) of State Pharmaceuticals Corporation (semigovernment) and privately owned retail pharmacies (n = 15) in 2003, 2006 and 2009 in a geographical area. Essential medicines (n = 28) were studied and, for each medicine, innovator, most sold generic and cheapest generic were monitored. The medicine's median price was compared with the international reference prices (IRP) to obtain the median price ratio. The daily wage of the lowest-paid government worker was used to calculate affordability.

RESULTS

Innovators were five to six-times the IRP at privately owned pharmacies and four to seven-times at the Rajya Osu Sala. The prices of generics were ≤1 the IRP during 6 years in privately owned and Rajya Osu Sala pharmacies. Cheapest generics were high in availability (>80%) throughout the study period. Innovators cost more than a day's wage of the lowest-paid government worker; in contrast, generics were always less than one day's wage. There seems to be no difference in affordability between privately owned or semigovernment pharmacies.

CONCLUSION

In Sri Lanka, generic medicines have effective pricing and are available and affordable. No drastic changes in prices of medicine in the private sector were observed over the 6 years despite removal of price control.