Hospital Pharmacy - June 2019 - 192

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Hospital Pharmacy 54(3)

Figure 1. Showing average 7 concentration calibration (internal standard corrected) to assess linearity.

Sample Preparation

Results

Two 1-g meropenem pharmaceutical dose vials were emptied into a 250-mL beaker and reconstituted with 40 mL
water for injection, and 100 mL 0.9% saline was added and
the solution was stirred. Six 100-mL 0.9% saline polyvinyl
chloride IV bags were emptied completely, dried, and
injected using a 20-mL syringe with same amount (20 mL) of
reconstituted bulk solution (14 285 ppm) and incubated at
the relevant temperature, 22°C and 33°C. The concentration
of meropenem was measured every hour for 21 hours after
reconstitution and testing was performed in duplicate. The
infusion solution was considered stable while the percentage
of intact molecule remained above 90%.

Method Validation

Physical Observation
Two responses were measured: physical compatibility and
color change. The solutions stored in IV bags were examined
at every sampling interval for cloudiness, crystallization/precipitation, color change, and signs of interactions.

HPLC Assay
The samples were diluted 50-fold with mobile phase (700
μL), and paracetamol (250 μL; concentration 1000 ppm) was
used as an internal standard (meropenem concentration =
286 ppm). The diluted samples were injected (injection volume 10 μL) via an auto sampler onto a Synergi 4 μm,
POLAR-RP-80R, 250 × 4.6-mm column. The mobile phase
was composed of 10-mM ammonium acetate buffer adjusted
to pH 5.4 with acetic acid and acetonitrile (90:10: vol/vol),
isocratic elution at a flow rate of 2.8 mL/min. The UV detector wavelength was set to 290 nm and the column temperature was set at 50±1°C.

The internal standard corrected calibration curve displayed
good linearity over the concentration range of 0 to 500 µL/mL.
The representative linear equation was y = 0.9943x − 0.0566,
with a correlation coefficient (R2) of 0.9998 (Figure 1). The
regression line (R2 = .9996) in Figure 2 demonstrates linearity
in the range of 0 to 2000 ppm.
Good system precision was obtained where intrasample precision ranged between Percentage Relative Standard Deviation
(%RSD) 0.01% and 0.37%. Intraday precision attained ranged
between %RSD 0.25% and 1.90% and interday precision
obtained ranged between %RSD 1.79% and 5.64%.
The percentage error determined from all standard QC
samples was between 0.29 and 0.68%; therefore, percent
recovery values obtained were at least 99.32%. For all
blanks, there was no significant response. Meropenem reference standard solution was spiked with internal standard to
ensure that peaks are well resolved.
Increasing the column temperature decreased the pressure
and retention time. Slight changes in mobile phase pH displayed no significant difference in peak area or peak shape.
The robustness study demonstrated that the method can optimally perform reproducibly when parameters change slightly.
The limit of detection was 5.55 ppm and the limit of quantitation was 16.82 ppm.

Preliminary Results
The results of the preliminary NMR investigation are shown
in Figure 3. The solution was analyzed periodically by proton NMR with water suppression. The increase in peak
intensity in the spectra, most prominently at chemical shifts

Hospital Pharmacy - June 2019

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