Table 1.

Manufacturer, Preparation, Storage, and Chromatographic Specifications and Information about Method for Accelerated Degradation for 5 Antibiotics

			Study Days
Drug	Manufacturer, Lot, and Expiry Date	Diluent and Concentration (mg/mL)	23°C	4°C	Liquid Chromatographic Method	Accuracy (Deviation) and Reproducibility of Standard Curve	Method and Validation of Accelerated Degradation
Cefazolin	Novopharm Lot 352132 Expiry May 2009	NS: 5 and 40 D5W: 5 and 40	0, 1, 2, 7	0, 1, 2, 7, 11,14, 18, 28	Mobile phase: 12.5% acetonitrile* + 87.5% 0.025 M potassium phosphate dibasic† adjusted to pH 6.8 with phosphoric acid‡ Column: 25 cm × 4.6 mm C-18, 5-μm§ Flow rate: 1.0 mL/min Detection wavelength: 270 nm Retention time: 5.8–6.6 min	6 standards: 0.032–0.500 mg/mL 4-μL samples diluted 50-or 125-fold Deviation from known concentration (mean), for QC samples and standards: 2.02% Error of replicate analysis within a day (mean): 1.07% for standards and 0.76% for QC samples	Cefazolin (Fluka), 0.5 mg/mL, 80°C 9 samples over 193 min 31% remaining
Ceftazidime	GlaxoSmithKline Lot B272 Expiry Oct 2008	NS: 5 and 60 D5W: 5 and 40	0, 1, 2, 4, 7	0, 1, 2, 4, 7, 11, 14	Mobile phase: 7% acetonitrile* + 93% 0.05 M phosphoric acid‡ Column: 15 cm × 4.6 mm C-18, 3-μm¶ Flow rate: 1.0 mL/min Detection wavelength: 262 nm Retention time: 5.3–6.3 min	6 standards: 0.056–0.600 mg/mL 3-μL samples diluted 50-or 125-fold Deviation from known concentration (mean), for QC samples and standards: 1.88% Error of replicate analysis within a day (mean): 0.90% for standards and 0.77% for QC samples	Ceftazidime (Sigma-Aldrich), 2.0-mg/mL, 80°C 11 samples over 445 min 17% remaining
Ceftriaxone	Roche (Rocephin) Lot B 30646 Expiry Oct 2009	NS: 5 and 40 D5W: 5 and 40	0, 1, 2, 4, 7, 14	0, 1, 2, 4, 7, 14, 21	Mobile phase: 10% acetonitrile* + 90% 0.05 M phosphoric acid‡ Column: 15 cm × 4.6 mm C-18, 3-μm¶ Flow rate: 1.2 mL/min Detection wavelength: 262 nm Retention time: 6.8–8.1 min	6 standards: 0.031–0.500 mg/mL 4-μL samples diluted 50-or 125-fold Deviation from known concentration (mean) for QC samples and standards: 1.60% Error of replicate analysis within a day (mean): 1.40% for standards and 2.0% for QC samples	Ceftriaxone (Sigma-Aldrich), 0.4 mg/mL at 80°C 10 samples over 387 min 5% remaining
Clindamycin	Sandoz Lot 139820 Expiry May 2008	NS: 1 and 12 D5W: 1 and 12	0, 1, 2, 7	0, 1, 2, 7, 14, 21	Mobile phase: 7% acetonitrile* + 93% 0.05 M phosphoric acid‡ Column: 15 cm × 4.6 mm C-18, 3-μm¶ Flow rate: 1.0 mL/min Detection wavelength: 202 nm Retention time: 6.1–7.7 min	6 standards: 0.094–0.750 mg/mL 3-μL samples diluted 5-or 50-fold Deviation from known concentration (mean) for QC samples and standards: 1.85% Error of replicate analysis within a day (mean): 0.63% for standards and 1.07% for QC samples	Clindamycin (Sigma-Aldrich), 0.5 mg/mL at 80°C 22 samples over 28.25 days 17% remaining
Vancomycin	Hospira Lot 43-777-TB-22 Expiry Jan 1, 2008	NS: 1 and 5 D5W: 1 and 5	0, 1, 3, 4, 7	0, 1, 3, 4, 7, 11, 14, 18, 31	Mobile phase: 7% acetonitrile* + 92% triethylamine** adjusted to pH 3.2 with concentrated phosphoric acid‡ and 1% tetrahydrofuran†† Column: 25 cm × 4.6 mm C-18, 5-μm‡‡ Flow rate: 1.2 mL/min Detection wavelength: 280 nm Retention time: 4.7–5.4 min	6 standards: 0.125–3.000 mg/mL 3-μL samples injected directly or diluted 5-fold Deviation from known concentration (mean) for QC samples and standards: 1.61% Error of replicate analysis within a day (mean): 0.88% for standards and 0.84% for QC samples	Vancomycin (Sigma-Aldrich), 1.0 mg/mL, adjusted to pH 2.14 with HCl, at 80°C 10 samples over 117 min 25% remaining

D5W = dextrose 5% in water, HCl = hydrochloric acid, NS = normal saline (0.9% sodium chloride), QC = quality control.

^*Acetonitrile: OmniSolv, EMD Chemicals Inc, Gibbstown, New Jersey.

^†Potassium phosphate dibasic: catalogue no. P7386, Sigma-Aldrich, St Louis, Missouri.

^‡Phosphoric acid: catalogue no. P286, Fisher Scientific, Toronto, Ontario.

^§Waters Symmetry, part no. WAT054275, Waters Scientific Canada, Mississauga, Ontario.

^¶Supelcosil ABZ+Plus, catalogue no. 59194, Supelco, Oakville, Ontario.

^**Triethylamine, 2 mL/L: Sigma Chemical Co, St Louis, Missouri.

^††Tetrahydrofuran: Fisher Scientific, Fair Lawn, New Jersey.

^‡‡Ultrasphere ODS, catalogue no. 235329, Beckman Coulter, Fullerton, California.