I don't know about ceftriaxone, but if I recall well ceftazidime is only stable for a couple of hours as a stock solution. Maybe that corresponds to degradation of the antimicrobial? Have you checked if the activity remains the same?

Hi!

I never worked with Ceftriaxone and Ceftazidime.

However there are some cephalosporins (eg cephalexin) that may be unstable. Also should consider the presence of any of the excipients in the commercial preparation.

It could make a comparative study and assessment; effect of frozen preparations of Ceftriaxone and Ceftazidime on the antimicrobial activity. You might holder to be used G. stearothermophilus as a bacterial sensor of cephalosporins.

Oxidation Muhammad, I strong recommend you to cover the eppendorfs with aluminum paper.. The oxidation is a mix between oxygen and light oxidation.

The reason the oxidation or hydrolysis of betalactams rings that render a colour, this is similar to what happens with nitrocephin, a betalactmic that render a colour after hydrolysis and is used for betalactamase activity determination. Then the best is weight in the precision balance the exact powder that you need for each aliquot and store it at 4 grades or -20. Just resuspend it before use. This remain stable for only one week before active concentration decline. I hope help you...

Hi Muhamad, the stability of the ceftazidime solution is up to 6 hours at no more than 25ºC. Ceftriaxone should last up to 6 months at -80ºC. When I work with beta-lactams I try to prepare fresh solutions everyday, since many are quite unstable and also the freezing-thawing process may lead to degradation of the compounds.

Thank you Nuno Antunes, Rafael Althaus, Leandro sanchez, Alexandro Rodríguez-Rojas and Marilena Marino

Hi! In Philippine General Hospital, there was this case about Cefuroxime (innovator drug) exhibiting a color change as well from transparent to brownish color. Have you searched on the stability of those Cephalosporins? I think color change may be due to the degradation of the product upon exposure to air or heat, and/or possibly due to the excipients in the preparation. You should also check how these drugs were handled from shipment to storage then to dispensing. Since we are not sure if they still have therapeutic effects, we cannot say that they are still safe to use. This must also be reported to the manufacturer of the drug so they can assess their quality control procedures.

Hi Muhammed

i dont know how you did prepare the antibiotic stock, but you should know each an antibiotic has a diffrent conditions for preperation ,ex., ceftriaxone the solvent must be water ,the diluent water, store 7 days at 4C,3 months at-20C and 6 months at -70C. so ceftazidime; the solvent must be saturated NaHCO3 solution, the diluent water, store 1 day at 4C, 3months at -20Cand 6 months at -70C. i hope this information will help you. good luck.

Hi Muhammed, as a licensed Medical Technologist working in medical microbiology I have experienced the same. You must protect them from oxidation and keep them stored below -20 C. The manufacturer should be contacted. Of course you are using sterile solutions and running your own Quality Control to confirm sterility and effectiveness. Contact a hospital microbiology lab they should share their Quality Control methodology or procedure with you. It involves using serial dilutions of your antibiotic absorbed into disks of paper. You drop these disks on inoculated agar (the agar usually BAP is streaked for isolation with a loop containing an organism(pure culture of a microbe that is purchased in a freeze dried state and reconstituted in a sterile broth to a standard strength (of turbidity). the susceptibilty of the microbe is measured by the distance the growth stays from the antibiotic disk. This measures how effective your antibiotic is but the microbe its tested against must be consisitent so for QC testing we buy a freeze dried microbe with known and tested responses to antibiotics.

Hi you are true, do you know all beta-lactames antibiotica unstable , from my experience ,i usually use the fresh an antibiotic to avoid any repetition.

Salamo Alikom, the change in the color of cephalosporins doesn't mean degradation unless you check their spectra before and after color change. Sometimes color change (especially for solid powder cephalosporins) doesn't affect their activity.

The color of ceftriaxone or ceftazidime solutions ranges from light yellow to amber, depending on the length of storage, concentration and diluent used, and the color is not directly related with the activity of the solution.

I have worked with antibiotics and I have prepared stocks solutiosn of 1 mg/ml in destiled water o some times in buffer. If you want to know the apropiated solvent you can review the book "ANTIOBOTICS IN LABORATORY MEDICINE" of Victor Lorian (Edit)

"For Ceftriaxone use water for stock solutions (a mg/ml) and water as diluent to make solutions of 100 mcg/ml"

"For ceftazidime use solution of sodium carbonate (0.1 mg/ml) for stock solution (1 mg/ml) and water as diluent to make solutions of 100 mcg/ml"

this information was taken from the Victor Lorian Book

I would also say it is oxidation. Since this oxidation is most likely irreversible, I would question the potency based on bio-availability of the active. See attached for details on oxidation potentials.

http://www.mendeley.com/research/electrochemical-oxidation-determination-ceftriaxone-glassy-carbon-carbonnanotubemodified-glassy-carbon-electrodes/#

The antibiotics you use are comercial ones?. These products declare a content that ranges between 90% and 110%, please review the pharmacopoeias. So, you must know the exact content of these products or you must use USP STANDARDS or secundary standars, the pharmaceutical laboratory manufacturers could give away you some samples.

The chance in color of any antibiotic means there is oxidation reaction and this means the potency of the antibiotic is changed and can't be used in quality control or other research study.

You should use original powder of the antibiotics in in vitro studies, it is important to know the potency of the antibiotics and you should calculate the amount of the antibiotic for dilution using the potency value. It is not recommended to use commercial preparations for in vitro studies.

Bundles and bundles of thanks from the bottom of my heart to all of u :)

Some cephalosporines are chromogenic, the changing in the color usually means that the beta-lactamic ring has been hydrolized. For examples cefinase is a chromogenic ceph that in the laboratory is used to detect the bacterial production of beta-lactamases, this ceph change from pale yellow to red.

Those thing depends on chemical composition of active compound if its may be contain amine or hetro cyclic amine due to amine color turn to yellow and after long time its may be dark brown. Some time amine may be contain sulphar like impurity its also play important role for color change

Muhammad

The authors of the following article have studied the stability of the cefatriaxone at different temperatures and in different diluents and provide recommendations which essentially in 1 month for this drug at -20C.

Emilia Cantón, M.Jesus Esteban, Fernando Rius. 1993. Factors affecting the stability of ceftriaxone sodium in solution on storage. International Journal of Pharmaceutics. Volume 92, Issues 1–3, 3 May 1993, Pages 47–53

http://dx.doi.org/10.1016/0378-5173(93)90262-E,

it may be due to oxidation

I dont think you should be using them.

you have to know the chemical structure and if there is a fonction which can transforme by a reaction of oxidation.

Mostly cefarotoxime & cefatizamide are made in powder form & while injecting they were mixed with aq sol in order to prevent oxidation so while doing invitro studies use fresh solution

e,g ; ceftriaxone for injection 1GM

how long after reconstitution it become dark brown.

due to hydrolysis of beta lactamase ring

Dear Muhameed,

I could understand your feelings!. It seems not easy to work with those antibiotics. My guess would be, antibiotics can bind with the metal ions, especially, Fe(II)-antibiotics slowly oxidizes into Fe(III)-antibiotics and H2O2 in the presence of oxygen by changing colors. To avoid this you can add EDTA on your buffer or H2O and see this it happen again

Ramki