Vitamin drug interactions

Vitamin B12 generally is well tolerated and exhibits minimal adverse effects. Injection-site pain, pruritus, rash, and diarrhea have been reported. Drug interactions have been observed with omeprazole and ascorbic acid that decrease oral absorption. 

Chemical drug interactions result when two administered substances combine with each other chemically Tetracyclines complex with Ca (in milk), with aluminum (Al) and magnesium (Mg) (often components of antacids), and with Fe (in some multiple vitamins) to reduce the absorption of the tetracycline antibiotic. 

Other potential adverse effects include impaired absorption of fat-soluble vitamins A, D, E, and K hypernatremia and hyperchloremia GI obstruction and reduced bioavailability of acidic drugs such as warfarin, nicotinic acid, thyroxine, acetaminophen, hydrocortisone, hydrochlorothiazide, loperamide, and possibly iron. Drug interactions may be avoided by alternating administration times with an interval of 6 hours or greater between the BAR and other drugs. 

PPIs are usually well tolerated. Potential adverse effects include headache, dizziness, somnolence, diarrhea, constipation, nausea, and vitamin B12 deficiency. All PPIs can decrease the absorption of drugs such as ketoco-nazole or itraconazole that require an acidic environment for absorption. Other drug interactions vary with each agent. 

All quinolones interact with multivalent cations, forming chelation complexes resulting in reduced absorption. Major offenders are antacids vitamins containing calcium and iron can also be problematic. All fluoroquinolones interact with warfarin, didanosine (ddi), and phenytoin, resulting in decreased absorption or metabolism. Ciprofloxacin and other second-generation drugs interact with theophylline by decreasing its clearance, which leads to theophylline toxicity. 

Geriatric Considerations - Summary Primidone is poorly tolerated in older adults avoid use if possible. Dosage adjustments are required in renal impairment. Numerous drug interactions with primidone exist. Primidone may reduce bone mineral den-sitybyinterferingwith vitamin D catabolism. Calcium and vitamin D supplementation and monitoring of bone mineral density are recommended for older adults taking this drug. 

Drug interactions No formal drug interaction studies have been carried out. Clinical trials have indicated that Pulmozyme can be effectively and safely used in conjunction with standard cystic hbrosis therapies including oral, inhaled, and/or parenteral antibiotics, bronchodila-tors, enzyme supplements, vitamins, oral or inhaled corticosteroids, and analgesics. 

The preparation used in many of the described interactions between St. John s wort and conventional pharmaceutical products is the product manufactured by Lichtwer Pharma GmbH (Berlin, Germany). This product is marketed under the trade name, Jarsin (LI 160) in Germany and marketed in the United States under the trade name Kira . St. John s wort may also be sold in combination products with vitamins and other botanical preparations (32). The drug interaction potential between these combination products and cytochrome P450 (CYP) 3A and P-glycoprotein... 

PURPOSE AND RATIONALE During the last 10 years many uptake transporters as well as efflux transporters have been discovered in the GI and especially in the small intestine. They allow uptake of ions, amino acids, peptides, nucleic acids, sugars, organic acids, vitamins, cofactors and nucleosides. On the other hand, efflux transporters ensure protection of the organism from unwanted pathogen or compound delivery. Subsequently, cellular systems have been used to study uptake in mechanistic studies in more detail. Additionally inhibition studies provide hints on potential drag-drug interactions. 

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