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Biomedical subjects

L M Stolk

Publications and source records attributed to L M Stolk.

33 records · Page 2Linked to original sources
PubMed1986

Stability after freezing and thawing of solutions of mitomycin C in plastic minibags for intravesical use.

Solutions of 0.6 mg/ml mitomycin C (Mutamycin) in NaCl solution 0.9% in plastic minibags for intravesical use were stored at -20 degrees C and -30 degrees C and thawed by microwave radiation. Both unbuffered solutions and solutions buffered to approximately pH 7.5 were investigated. Concentrations were measured with HPLC. During freezing and storage at -20 degrees C sometimes crystallization of mitomycin C occurred. However, both buffered and unbuffered solutions could be frozen at -30 degrees C during at least four weeks and subsequently thawed without loss of content. Unbuffered mitomycin C solutions could be refrozen at -30 degrees C for another four weeks. Also buffered and unbuffered solutions of another brand of mitomycin C (Mitomycin-C Kyowa) could be frozen at -30 degrees C during four weeks without significant deterioration.

Administration, Intravesical↗
PubMed1986

Stability of solutions of doxorubicin and epirubicin in plastic minibags for intravesical use after storage at -20 degrees C and thawing by microwave radiation.

Doxorubicin and epirubicin solutions in plastic minibags for intravesical use were stored at -20 degrees C and thawed at room temperature or by microwave radiation. Concentrations were measured with HPLC and TLC. Doxorubicin and epirubicin solutions could be frozen and stored at -20 degrees C during at least two and four weeks, respectively, and subsequently thawed without loss of content. When the thawed doxorubicin solutions were refrozen and thawed again five weeks later, only a slight decrease of content was measured.

Doxorubicin↗
PubMed1986

Acetylation phenotype and skin complexion.

The relationship of acetylation phenotype to skin complexion was studied in 155 healthy Caucasians. Individuals received 500 mg sulphadimidine at 11.00 p.m.; urine was collected eight hours later. The percentage of acetylated sulphadimidine in urine was measured with high performance liquid chromatography. There was a slight but insignificant preponderance of slow acetylators in the dark skin types. It is concluded that slow acetylation phenotype is not correlated with light skin complexion. Therefore, it is unlikely that acetylation of xenobiotic carcinogens plays a dominant role in melanoma risk.

Acetyltransferases↗
PubMed1985

Formulation of a stable p-acetylaminohippurate infusion fluid and determination of the serum concentrations.

An infusion fluid with p-acetylaminohippurate (PACAH) was formulated and a method for analysis of PACAH in serum, urine and infusion fluid based on reversed phase HPLC was developed. No significant degradation could be observed after steam sterilization for twenty minutes at 120 degrees C. From the results of an investigation of the degradation rate at elevated temperatures a negligible loss of content during storage for three years at 20 degrees C could be predicted. Steady state serum concentrations of PACAH after constant infusion were determined.

Aminohippuric Acids↗
PubMed1985

Comparison of bioavailability and phototoxicity of two oral preparations of 5-methoxypsoralen.

5-Methoxypsoralen (5-MOP) (Psoraderm 5) tablets obtained from France and 5-MOP micronized in capsules (manufactured in our pharmacy department) were administered to seven psoriasis patients in a 1.2 mg/kg body weight dose schedule. Bioavailability and phototoxicity were compared. It was found that the maximum serum concentration and the area under the concentration curve were significantly higher (P less than 0.01) after administration of the capsules, indicating higher bioavailability. No erythema developed in any of the patients after administration of the tablets, whereas with the capsules four of the patients developed erythema at the test site. The absence of erythema following the use of the tablets is probably due to the poor bioavailability of this preparation.

5-Methoxypsoralen↗
PubMed1984

Formulation of a stable vidarabine phosphate injection.

An injection fluid with vidarabine phosphate (37.5 mg/ml, pH 7.4) was formulated. After steam sterilization for 20 min at 120 degrees C a 6.1% degradation was observed. No significant (p greater than 0.05) degradation could be observed after heating in steam for 30 min at 100 degrees C and after storage for four months at 4 degrees C. From the results of an investigation of the degradation rate at elevated temperatures a negligible loss of content after a three years' storage period at 4 degrees C could be predicted.

Chromatography, High Pressure Liquid↗
PubMed1983

Formulation of a stable vidarabine infusion fluid.

Decomposition of vidarabine in a 5% glucose infusion fluid after steam sterilization was measured by HPLC and TLC analysis. After sterilization for 60 minutes at 100 degrees C and 20 minutes at 120 degrees C no degradation could be observed. A slight but significant degradation was observed after sterilization for 60 minutes at 120 degrees C followed by storage for eight months. Assuming 5% loss of content to be acceptable, it was concluded that a vidarabine infusion fluid can be sterilized for 20 minutes at 120 degrees C and stored at room temperature for at least eight months afterwards.

Adenine↗
PubMed1981

Serum and urine concentrations of 5-methoxypsoralen after oral administration.

Serum and urine concentrations were measured after oral administration of 5-methoxypsoralen (0.6 mg/kg or I.2 mg/kg) to psoriasis patients. A dose of 0.6 mg/kg resulted in low serum concentrations, but after I.2 mg/kg, much higher serum concentrations were reached. There was much individual variation in the time required for reaching peak serum levels. Minute amounts of unchanged 5-methoxypsoralen were excreted in urine. Much larger amounts were excreted as conjugates.

5-Methoxypsoralen↗
PubMedDate not supplied

Analysis of methadone and its primary metabolite in meconium.

Methods for analysis of methadone and its principal metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in meconium, based on fluorescence polarization immunoassay (FPIA) and high-performance liquid chromatography (HPLC) and diode array detection were developed. Meconium and urine samples of 16 neonates from 15 methadone-using mothers were analyzed. Because of the lower detection limit and the possibility of coanalyzing EDDP, meconium analysis with HPLC for detecting methadone use is very much preferable to FPIA. Identical results were obtained with HPLC analysis for both matrices: methadone or EDDP or both could be detected in the urine and meconium samples from 15 children. The amount of EDDP in meconium was much higher than the amount of methadone (ratio, 9.6). EDDP only was detected in eight of the meconium samples. A positive correlation was found between the methadone dose of the mothers and the methadone concentration in meconium, but not with the EDDP concentration in meconium.

Chromatography, High Pressure Liquid↗