Folic acid absorption

Patients receiving sulfasalazine should receive oral folic acid supplementation since sulfasalazine inhibits folic acid absorption. 

The L. casei method described here can also be used to determine absorption of folic acid. Five milligrams of folic acid is given by mouth samples are obtained at 0, 2, 4, 6, and 8 hours. In cases of deficient folic acid absorption, normal peak levels are not obtained in the malabsorption syndrome, a flat curve indicates no absorption. Normal peak levels are maintained during 2-4 hour intervals (B3). 

The anemia of hyperthyroidism is usually normochromic and caused by increased red blood cell turnover. The anemia of hypothyroidism may be normochromic, hyperchromic, or hypochromic and may be due to decreased production rate, decreased iron absorption, decreased folic acid absorption, or to autoimmune pernicious anemia. LDH, lactic dehydrogenase AST, aspartate aminotransferase. 

Folic acid deficiency can be caused by drugs that interfere with folate absorption or metabolism. Phenytoin, some other anticonvulsants, oral contraceptives, and isoniazid can cause folic acid deficiency by interfering with folic acid absorption. Other drugs such as methotrexate and, to a lesser extent, trimethoprim and pyrimethamine, inhibit dihydrofolate reductase and may result in a deficiency of folate cofactors and ultimately in megaloblastic anemia. 

Sulfasalazine reduces folic acid absorption, but rarely to a chnically significant extent, although megaloblastic anemia has rarely been documented (51,52). 

Franklin JL, Rosenberg IH. Impaired folic acid absorption in inflammatory bowel disease effects of salicylazosulfapyridine (Azulfidine). Gastroenterology (1973) 64, 517-25. 

Shafer, R. B. and Nuttal, F. Q. (1975) Calcium and folic acid absorption in patients taking anticonvulsant drugs. J. din. Endocr., 41, 1125. 

Antacids (aluminium hydroxide, sodium bicarbonate) Reduces calcium, copper and folic acid absorption... 

Bile acid sequestrants may interfere with die digestion of fats and prevent die absorption of die fat-soluble vitamins (vitamins A, D, E, and K) and folic acid. When die bile acid sequestrants are used for long-term therapy, vitamins A and D may be given in a water-soluble form or administered parenterally. If bleedingtendencies occur as die result of vitamin K deficiency, parenteral vitamin K is administered for immediate treatment, and oral vitamin K is given for prevention of a deficiency in the futum... 

Pernicious anemia arises when vitamin B,2 deficiency blocks the metabohsm of folic acid, leading to functional folate deficiency. This impairs erythropoiesis, causing immature precursors of erythrocytes to be released into the circulation (megaloblastic anemia). The commonest cause of pernicious anemia is failure of the absorption of vitamin B,2 rather than dietary deficiency. This can be due to failure of intrinsic factor secretion caused by autoimmune disease of parietal cells or to generation of anti-intrinsic factor antibodies. 

Deficiency of folic acid Decreased intake, defective absorption, or increased demand (eg, in pregnancy) for folate... 

When treating folic acid deficiency, an initial daily dose of 1 mg/day by mouth typically is effective. Absorption of folic acid generally is rapid and complete. However, patients with malabsorption syndromes may require larger doses (up to 5 mg/day). Similar to vitamin B12 deficiency, resolution of symptoms and reticulocytosis is prompt, occurring within days of commencing therapy. Hgb will start to rise after 2 weeks of therapy and may take from 2 to 4 months to resolve the deficiency completely. Afterwards, if the underlying deficiency is corrected, folic acid replacement can be discontinued. However, in cases where folic acid is consumed rapidly or absorbed poorly, chronic replacement may be required. 

Phenytoin decreases folic add absorption, but folic acid replacement enhances phenytoin clearance and can result in loss of efficacy. Phenytoin tablets and suspension contain phenytoin acid, while the capsules and parenteral solution are phenytoin sodium, which is 92% phenytoin. Clinicians should remember that there are two different strengths of phenytoin suspension and capsules. 

Anticonvulsants Vitamin D and folic acid impaired absorption... 

R6. Rodriguez-Molina, R., Cancio, M., and Asenjo, C. F., The effect of folic acid on the steatorrhea of tropical sprue and other tests for intestinal absorption. Am. J. Trop. Med. Hyg. 9, 308-314 (1960). 

Theory Folic acid (I) undergoes cleavage by reduction with Zn-Hg in acidic medium to yield p-aminobenzoylglutamic acid (II). The primary aromatic amino group present in the latter is subsequently diazotized in the usual manner and coupled in acidic solution with N-(l-naphthyl)-ethylenediamine hydrochloride in the absence of light (caution). The colour thus produced has a maximum absorption at 550 nm and the extinction (E) is consequently compared with a calibration curve obtained from / -aminobcnzoic acid (PABA) that has been duly diazotized and coupled exactly in the same fashion as the/ -aminobcnzoylglutamic acid. 

Part—IV has been entirely devoted to various Optical Methods that find their legitimate recognition in the arsenal of pharmaceutical analytical techniques and have been spread over nine chapters. Refractometry (Chapter 18) deals with refractive index, refractivity, critical micelle concentration (CMC) of various important substances. Polarimetry (Chapter 19) describes optical rotation and specific optical rotation of important pharmaceutical substances. Nephelometry and turbidimetry (Chapter 20) have been treated with sufficient detail with typical examples of chloroetracyclin, sulphate and phosphate ions. Ultraviolet and absorption spectrophotometry (Chapter 21) have been discussed with adequate depth and with regard to various vital theoretical considerations, single-beam and double-beam spectrophotometers besides typical examples amoxycillin trihydrate, folic acid, glyceryl trinitrate tablets and stilbosterol. Infrared spectrophotometry (IR) (Chapter 22) essentially deals with a brief introduction of group-frequency... 

The healthy small intestine contains only a small bacterial population, unlike the colon. However, an acute infection of the mucosa by a virus, bacterium or other parasite can reduce its motility, allowing a huge proliferation of the resident bacteria. Absorption of both macro- and micronutrients is impaired, resulting in the disorder known as sprue. Folic acid is particularly poorly absorbed, causing reduced rates of repair of mucosal cells. Hence, the damage persists and worsens to create a vicious circle. Treatment involves administration of an antibiotic to kill the bacteria and folic acid to allow damaged tissue to recover. The clinical presentation includes bulky stools, steatorrhoea (fatty faeces) and weight loss. 

Blood levels of folic acid may become inadequate due to dietary insufficiency or poor absorption due to Intestinal problems or alcoholism. 

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