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“A significant negative correlation between theophylline and circulating levels of vitamin B6 was demonstrated in the subjects of this study (rs = -0.657, p < 0.001).”
“However, theophylline-related tremor was markedly reduced (p < 0.01) with vitamin B-6 supplementation after a single dose of theophylline and a similar but nonsignificant trend was observed with repeated doses.”
“These findings suggest that vitamin B-6 supplementation with theophylline therapy may have some beneficial effects.”
“This study investigates whether vitamin B-6 supplementation reduces the stimulatory effects of theophylline (a pyridoxal kinase antagonist) on the nervous system.”
The American journal of clinical nutrition • 1994 | View Paper
“A placebo-controlled, double-blind study indicated that theophylline administration to apparently healthy, young men induced significantly depressed plasma pyridoxal-5'-phosphate levels.”
“Both plasma pyridoxal-5'-phosphate levels and the tryptophan load test results normalized after 1 week of pyridoxine supplementation, indicating that 10 mg pyridoxine per day was effective to counteract the antagonistic effect of short-term theophylline therapy on vitamin B6 metabolism.”
“During theophylline therapy , erythrocyte pyridoxal kinase levels increased nearly twofold from an initial mean level of 24.2 +/- 4.0 (+/- SD) nmol to 46.9 +/- 7.3 nmol pyridoxal-5'-phosphate per gram of hemoglobin per hour.”
“Nevertheless, erythrocyte pyridoxal-5'-phosphate levels in subjects given theophylline decreased significantly (p = 0.03) from pretreatment levels.”
“This partially counteracted the effect of theophylline on vitamin B6 metabolism.”
Nederlands tijdschrift voor geneeskunde • 1997 | View Paper
“A significant negative correlation between the serum levels of PLP and theophylline was demonstrated in the subjects of this study (rs = -0.609, p < 0.001).”
“From these results, we conclude that theophylline induces a depression of circulating PLP levels in asthmatic children.”
“Oral administration of 200 mg of theophylline (TheoDur) to 5 children with asthma significantly depressed serum PLP levels 4 h after the drug intake (p < 0.05), whereas theophylline did not affect serum PL levels.”
“ Theophylline administration to seven healthy male volunteers resulted in a rapid and significant decline in both plasma and erythrocyte pyridoxal-5'-phosphate levels.”
“An in vitro study showed that theophylline did not interfere with the high performance liquid chromatography assay for pyridoxal-5'-phosphate, indicating that theophylline could affect liver metabolism of vitamin B6.”
“ Theophylline was administered to a group of 17 volunteers and resulted in large reductions in plasma pyridoxal-5'-phosphate levels, while plasma pyridoxal levels and urinary 4-pyridoxic acid excretion were unaffected by theophylline therapy.”
International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition • 1988 | View Paper
“ Theophylline therapy depresses plasma pyridoxal-5'-phosphate ( PLP ), the active metabolite of pyridoxine, suggesting that theophylline-induced seizures might be amenable to treatment with pyridoxine.”
Veterinary and human toxicology • 1999 | View Paper
“Serum theophylline levels and plasma PLP levels showed significant negative correlation prior to pyridoxine infusion with a mean peak theophylline level of 182 micrograms/ml and a mean low PLP level of 64 nM/L. Electroencephalogram (EEG) tracings were obtained before infusions, during theophylline infusion and during pyridoxine infusion.”
“ Theophylline therapy for asthma has been observed to depress plasma pyridoxal 5'-phosphate (PLP) levels which may decrease gamma-aminobutyric acid (GABA) synthesis and thereby contribute to seizures.”