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Biomedical subjects

T F Hipple

Publications and source records attributed to T F Hipple.

At least 19 recordsLinked to original sources
PubMed1999

Stability of lamotrigine in two extemporaneously prepared oral suspensions at 4 and 25 degrees C.

The stability of lamotrigine 1 mg/mL in two extemporaneously prepared oral suspensions at 4 and 25 degrees C was studied. Lamotrigine tablets were ground to powder, and the powder was combined with a 1:1 mixture of Ora-Sweet and Ora-Plus or a 1:1 mixture of Ora-Sweet SF and Ora-Plus (Paddock Laboratories) to produce two 1-mg/mL suspensions. One 100-mg lamotrigine tablet was used to prepare one 100-mL batch of each suspension. The suspensions were stored in amber polyethylene terephthalate prescription bottles at 4 or 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for analysis of lamotrigine content by high-performance liquid chromatography; pH was measured, and the samples were visually observed against a black and white background. The mean concentration of lamotrigine was >99% of the initial concentration in all samples throughout the 91-day study period; there was no change in apparent pH, odor, or physical appearance. Lamotrigine 1 mg/mL in two extemporaneously compounded oral suspensions was stable for 91 days in polyethylene terephthalate prescription bottles at 4 and 25 degrees C.

Administration, Oral↗
PubMed1998

Stability of enalapril maleate in three extemporaneously prepared oral liquids.

The stability of enalapril 1 mg/mL (as the maleate) in deionized water, citrate buffer solution, and a sweetened suspending agent at two temperatures was studied. Twenty enalapril 10-mg tablets were crushed to a powder. Deionized water, citrate buffer solution, or sweetened vehicle was added to produce three 200-mL batches of each liquid; the expected final concentration of enalapril in each was 1 mg/mL. Each formulation was stored in 10 60-mL bottles, 5 of which were stored at 4 degrees C and 5 at 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for visual inspection and analysis by high-performance liquid chromatography; pH was measured at each sampling time as well. The mean concentration of enalapril in the three liquids at 4 degrees C was > 94% of the initial concentration throughout the 91-day study period. At 25 degrees C, the mean concentration of enalapril was > 90% for 56 days and > 92% for 91 days in both citrate buffer solution and sweetened vehicle. The pH of the liquid prepared with deionized water and stored at 25 degrees C decreased by 2.0 pH units. Enalapril 1 mg/mL (as the maleate) in three extemporaneously compounded oral liquids was stable for 91 days at 4 and 25 degrees C with the exception of enalapril in deionized water, which was stable for only 56 days at 25 degrees C.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Stability of pyrimethamine in a liquid dosage formulation stored for three months.

The stability of pyrimethamine in a liquid dosage formulation stored for up to three months was studies. Commercially available 25-mg pyrimethamine tablets were crushed with a mortar and pestle and mixed with a 1:1 mixture of Simple Syrup, NF, and 1% methylcellulose to yield a suspension with a pyrimethamine concentration of 2 mg/mL. The suspension was poured into 10 amber plastic and 10 amber glass prescription bottles; 5 plastic and 5 glass bottles were stored at 4 degrees C, and the remaining bottles were kept at 25 degrees C. Samples were collected at intervals up to 91 days and tested for pyrimethamine concentration by stability-indicating high-performance liquid chromatography. Pyrimethamine remained stable throughout the three-month study period under all conditions. At 4 degrees C, pyrimethamine concentrations remained above 96% of the initial concentration; at 25 degrees C, pyrimethamine concentrations remained above 91%. No substantial changes in pH were observed. Pyrimethamine was stable for at least 91 days in an oral suspension stored in plastic or glass prescription bottles at 4 or 25 degrees C.

Anti-Infective Agents↗
PubMed1995

Stability of cisapride in a liquid dosage form at two temperatures.

OBJECTIVE: To determine the stability of cisapride in a liquid dosage form stored in plastic bottles at 2 temperatures. DESIGN: Cisapride tablets were used to prepare a suspension in equal volumes of methylcellulose 1% and simple syrup to yield a concentration of 1 mg/mL. The cisapride suspension was stored in 10 amber plastic prescription bottles. Five bottles were stored at room temperature (25 +/- 0.1 degrees C) and 5 under refrigeration (4 degrees C). Samples were drawn from each bottle immediately after mixing (day 0), and at 7, 14, 28, 42, 56, 70, and 91 days of storage at each temperature. All samples were analyzed in duplicate on each day of analysis. Cisapride was measured by a stability-indicating HPLC method. RESULTS: The mean concentration of cisapride exceeded 90% of its initial concentration throughout the 91-day study period at 4 degrees C, but only during the first 28 days at 25 degrees C. No significant change in pH was observed during the study period. CONCLUSIONS: Cisapride was stable in a suspension for 91 days at 4 degrees C and 28 days at 25 degrees C in amber plastic prescription bottles.

Chromatography, High Pressure Liquid↗
PubMed1994

Stability of rifampin in two suspensions at room temperature.

The objective of our study was to determine the stability of rifampin (rifampcin) in two extemporaneously prepared suspensions at room temperature. Two suspensions were prepared in syrup by using intravenous rifampin (A) or rifampin capsules (B). Each suspension was stored in five plastic prescription bottles. During the first week, the mean measured concentrations of rifampin were nearly 100% of initial concentration in suspension A, but were 77-83% of the expected (labelled) concentration in suspension B. The maximum concentrations of rifampin were observed immediately after preparation of suspension A, but not until 14 days in suspension B. On day 56, the mean concentration of rifampin was about 95% of initial concentration in suspension A, and close to 90% of the labelled potency (10 mg/ml) in suspension B. Rifampin was found to be chemically stable in each suspension for 56 days at room temperature. Suspensions prepared from the capsules may be non-homogeneous and lead to unsatisfactory dosing.

Capsules↗
PubMed1994

Effect of preparation method and storage on rifampin concentration in suspensions.

OBJECTIVE: To determine the effect of four preparation methods and extended storage on rifampin concentration in extemporaneously prepared suspensions. DESIGN: Four preparation methods were used: mixing intravenous (i.v.) rifampin in syrup (A); manufacturer's recommended technique of mixing capsule (Rifadin) contents in syrup (B); triturating capsule contents in syrup into a paste and adding remaining syrup while mixing (C); and triturating capsule contents in syrup into a paste, adding syrup, retriturating the slurry, and adding remaining syrup while mixing (D). Samples were drawn from each of five bottles of each of the four preparations stored at 4 degrees C, immediately after mixing (day 0), and on days 7, 14, 28, 42, 56, 70, and 91 days during storage. Rifampin was measured by a stability-indicating HPLC method. RESULTS: The measured mean concentrations of rifampin were nearly 100 percent of the initial concentration in the suspension prepared from i.v. rifampin solution (method A) during the first 56 days of storage. In contrast, the measured concentrations were substantially lower than expected in the suspensions prepared by methods B, C, and D. The mean rifampin concentrations in suspensions prepared by methods B, C, and D were only 14.5, 38.6, and 68 percent, respectively, of the initial concentration achieved by method A. The rifampin concentrations increased with storage time in suspensions prepared by methods B, C, and D. The mean rifampin concentration was lower than 90 percent during the first 14 days with methods B and C, and the first 7 days with method D. The highest mean concentrations were observed on day 42 with method B, and on day 28 with methods C and D. All methods yielded 90% of the labeled potency (10 mg/mL) on day 56. CONCLUSIONS: Our results showed that preparation method can influence the dispersion, and thus the measured concentration, of rifampin in aliquots of suspensions prepared from capsules and stored in plastic bottles. Suspensions prepared from capsules led to lower-than-expected rifampin concentrations; those prepared from i.v. rifampin did not. Rifampin was stable in each type of suspension for 56 days at 4 degrees C.

Chemistry, Pharmaceutical↗
PubMed1993

Stability of lorazepam diluted in bacteriostatic water for injection at two temperatures.

Lorazepam is commonly used to produce sedation in infants. As errors may occur with the measurement of small volumes of concentrated drugs, we studied the stability of lorazepam diluted from 4 mg/ml to 1 mg/ml in bacteriostatic water for injection at two temperatures. The diluted lorazepam was stored in 10 glass vials (five at 22 degrees C and five at 4 degrees C). Samples were collected at 0, 7, 14, 28, 42, 56, 70 and 91 days after storage at each temperature. Lorazepam was measured in duplicate from each of five vials (n = 10) at each temperature by a specific and stability-indicating high-performance liquid chromatographic (HPLC) method. After 7 days' storage, the mean lorazepam concentration was 88% of the original concentration at 22 degrees C, and 90% of the original concentration at 4 degrees C. After 2 weeks of storage, the mean lorazepam concentration was 42% of the original concentration at 22 degrees C, and 1.5% of the original concentration at 4 degrees C. Crystals appeared after 4 weeks of storage at 22 degrees C and after 2 weeks of storage at 4 degrees C. At 3 months the mean lorazepam concentration was 6.1% and 7.5% of the original concentration at 22 degrees C and 4 degrees C, respectively. Thus, lorazepam diluted in bacteriostatic water for injection and stored in glass vials is stable for less than 7 days at 22 degrees C and for 7 days at 4 degrees C.

Chromatography, High Pressure Liquid↗
PubMed1993

Stability of spironolactone in an extemporaneously prepared suspension at two temperatures.

OBJECTIVE: To determine the stability of spironolactone in an extemporaneously prepared suspension at 22 and 4 degrees C over a three-month storage period. DESIGN: Spironolactone suspension (1 mg/mL) was prepared in syrup NF, carboxymethylcellulose, and purified water USP. The suspension was stored in ten amber glass prescription bottles; five were stored at 22 degrees C and five at 4 degrees C. Samples were drawn from each bottle and analyzed in duplicate (n = 10) on days 0, 7, 14, 28, 42, 56, 70, and 91. Spironolactone concentrations were measured by a reproducible and stability-indicating HPLC method. Inspection of visual and pH changes also was performed on each study day. RESULTS: The mean concentration of spironolactone was always higher than 98 percent of its initial concentration. The pH and appearance of the suspension did not change substantially. CONCLUSIONS: Spironolactone was stable in a suspension containing syrup, carboxymethylcellulose, and purified water for three months during storage in amber glass bottles at both 22 and 4 degrees C.

Carboxymethylcellulose Sodium↗
PubMed1986

Interlot variability in gentamicin and tobramycin concentration and its possible significance.

Aminoglycoside therapy is routinely monitored at many institutions. It is widely known that serum concentrations of gentamicin and tobramycin may differ markedly among patients receiving the same doses of these drugs. One possible source of this variability may be interlot variation in the concentration of these drugs in commercial preparations. A study was designed to evaluate inter- and intralot variation in gentamicin and tobramycin concentrations at the labeled concentrations of 10 and 40 mg/ml. Multiple samples from six to 10 lots of commercially available gentamicin sulfate injection (Elkins-Sinn, Inc.) and tobramycin sulfate injection (Eli Lilly & Co.) were studied at each concentration. The actual percentage concentration of gentamicin in various lots ranged from 101 to 134% of the labeled concentrations; the actual percentage range was 101-109% at 10 mg/ml and 102-134% at 40 mg/ml labeled concentration. The actual percentage concentration of tobramycin in various lots ranged from 103 to 122% of labeled concentration; the actual percentage range was 107-117% at 10 mg/ml and 103-122% at 40 mg/ml labeled concentration. The intralot variation was less than 4% for both drugs at two concentrations. Based on these results, an 80-mg dose may in fact contain 107 mg of gentamicin or 98 mg of tobramycin. This may be clinically important in the care of patients and may at least in part explain the large variation in serum concentrations and difficulty in prediction of dosage requirements from routine monitoring. Furthermore, the available literature on pharmacokinetics, efficacy, and toxicity has not considered this interlot variation in aminoglycoside concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Labeling↗
PubMed1986

Stability of phenobarbital sodium diluted in 0.9% sodium chloride injection.

The stability of phenobarbital sodium diluted to 10 mg/mL in 0.9% sodium chloride injection was studied at an unadjusted pH (8.5) and an adjusted pH (10.0) at 4 degrees C over a four-week period. The phenobarbital concentrations were measured before dilution and at 1, 2, 3, 7, 14, and 28 days using high-performance liquid chromatography. The observed phenobarbital concentrations ranged from 98.0 to 106.0% of initial concentration at the unadjusted pH and from 96.7 to 108.5% of initial concentration at the adjusted pH. The diluted phenobarbital sodium was stable over a four-week period at 4 degrees C without the need for pH adjustment.

Drug Stability↗