Pyridoxine

 Risk Factor: A
 Class: VITAMINS

Contents of this page:

Fetal Risk Summary
Breast Feeding Summary
References
Questions and Answers

Fetal Risk Summary

Pyridoxine (vitamin B6), a water-soluble B complex vitamin, acts as an essential coenzyme involved in the metabolism of amino acids, carbohydrates, and lipids (1). The National Academy of Sciences' recommended dietary allowance (RDA) for pyridoxine in pregnancy is 2.2 mg (1).

Pyridoxine is actively transported to the fetus (2,3 and 4). Like other B complex vitamins, concentrations of pyridoxine in the fetus and newborn are higher than in the mother and are directly proportional to maternal intake (5,6,7,8,9,10,11,12,13,14,15 and 16). Actual pyridoxine levels vary from report to report because of the nutritional status of the populations studied and the microbiologic assays used, but usually indicate an approximate newborn:maternal ratio of 2:1 with levels ranging from 2287 ng/mL for newborns and 1351 ng/mL for mothers (4,14,15 and 16).

Pyridoxine deficiency without clinical symptoms is common during pregnancy (10,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33 and 34). Clinical symptoms consisting of oral lesions have been reported, however, in severe B6 deficiency (35). Supplementation with multivitamin products reduces, but does not always eliminate, the incidence of pyridoxine hypovitaminemia (16).

Severe vitamin B6 deficiency is teratogenic in experimental animals (36,37). No reports of human malformations linked to B6 deficiency have been located. A brief report in 1976 described an anencephalic fetus resulting from a woman treated with high doses of pyridoxine and other vitamins and nutrients for psychiatric reasons, but the relationship between the defect and the vitamins is unknown (38).

The effects on the mother and fetus resulting from pyridoxine deficiency or excess are controversial. These effects can be summarized as: Pregnancy-induced hypertension (PIH, toxemia, preeclampsia, eclampsia) Gestational diabetes mellitus Infantile convulsions Nausea and vomiting including hyperemesis gravidarum Congenital malformations Miscellaneous Several researchers have claimed that pyridoxine deficiency is associated with the development of PIH (12,39,40 and 41). Others have not found this relationship (10,19,42,43). One group of investigators demonstrated that women with PIH excreted larger amounts of xanthurenic acid in their urine after a loading dose of dl-tryptophan than did normal pregnant women (39). Although the test was not totally specific for PIH, they theorized that it could be of value for early detection of the disease and was indicative of abnormal pyridoxine-niacin-protein metabolism. In another study, 410 women treated with 10 mg of pyridoxine daily were compared with 410 controls (40). PIH occurred in 18 (4.4%) of the untreated controls and in 7 (1.7%) of the pyridoxine-supplemented patients, a significant difference. In an earlier report, no significant differences were found between women with PIH and normal controls in urinary excretion of 4-pyridoxic acid, a pyridoxine metabolite, after a loading dose of the vitamin (19). Some investigators have measured lower levels of pyridoxine in mothers with PIH than in mothers without PIH (12). The difference in levels between the newborns of PIH and normal mothers was more than 2-fold and highly significant. In a 1961 Swedish report, pyridoxine levels in 10 women with PIH were compared with those in 26 women with uncomplicated pregnancies (42). The difference between the mean levels of the two groups, 25 and 33 ng/mL, respectively, was not significant. Similarly, others have been unable to find a correlation between pyridoxine levels and PIH (10,43).

Pyridoxine levels were studied in 14 pregnant women with an abnormal glucose tolerance test (GTT), and 13 of these patients were shown to be pyridoxine deficient (44). All were placed on a diet and given 100 mg of pyridoxine/day for 14 days, after which only two were diagnosed as having gestational diabetes mellitus. The effect of the diet on the GTT was said to be negligible, although a control group was not used. Other investigators duplicated these results in 13 women using the same dose of pyridoxine but without mentioning any dietary manipulation and without controls (45). However, a third study was unable to demonstrate a beneficial effect in four patients with an abnormal GTT using 100 mg of B6 for 21 days (46). Moreover, all of the mothers had large-for-gestational-age infants, an expected complication of diabetic pregnancies. In 13 gestational diabetic women treated with the doses of pyridoxine described above, an improvement was observed in the GTT in 2 patients, a worsening was seen in 6, and no significant change occurred in the remaining 5 (47).

An association between pyridoxine and infantile convulsions was first described in the mid-1950s (48,49,50,51 and 52). Some infants fed a diet deficient in this vitamin developed intractable seizures that responded only to pyridoxine. A 1967 publication reviewed this complication in infants and differentiated between the states of pyridoxine deficiency and dependency (53). Whether or not these states can be induced in utero is open to question. As noted earlier, pyridoxine deficiency is common during pregnancy, even in well-nourished women, but the fetus accumulates the vitamin, although at lower levels, even in the face of maternal hypovitaminemia. Reports of seizures in newborn infants delivered from mothers with pyridoxine deficiency have not been located. On the other hand, high doses of pyridoxine early in gestation in one patient were suspected of altering the normal metabolism of pyridoxine, leading to intractable convulsions in the newborn (54). The woman, in whom two pregnancies were complicated by hyperemesis gravidarum, was treated with frequent injections of pyridoxine and thiamine, 50 mg each (54). The first newborn began convulsing 4 hours after birth and died within 30 hours. The second infant began mild twitching at 3 hours of age and progressed to severe generalized convulsions on the 5th day. Successful treatment was eventually accomplished with pyridoxine but not before marked mental retardation had occurred. The authors of this report postulated that the fetus, exposed to high doses of pyridoxine, developed an adaptive enzyme system that was capable of rapidly metabolizing the vitamin; following delivery, this adaptation was manifested by pyridoxine dependency and convulsions (54). Since this case, more than 50 additional cases of pyridoxine dependency have been reported, and the disease is now thought to be an inherited autosomal recessive disorder (55). In utero dependency-induced convulsions in three successive pregnancies in one woman have been reported (56). The first two newborns diedone during the 7th week and one on day 2as a result of intractable convulsions. During the third pregnancy, in utero convulsions stopped after the mother was treated with 110 mg/day of pyridoxine 4 days before delivery. Following birth, the newborn was treated with pyridoxine. Convulsions occurred on three separate occasions when vitamin therapy was withheld and then abated when therapy was restarted.

The first use of pyridoxine for severe nausea and vomiting of pregnancy (hyperemesis gravidarum) was reported in 1942 (57). Individual injections ranged from 10 to 100 mg, with total doses up to 1500 mg being given. Satisfactory relief was obtained in most cases. In one study, patients were successfully treated with IM doses of 50100 mg 3 times weekly (58). Another report described a single patient with hyperemesis who responded to an IV mixture of high-dose B complex vitamins, including 50 mg of pyridoxine, each day for 3 days (59). Much smaller doses were used in a study of 17 patients (60). IM doses of 5 mg every 24 days were administered to these patients, with an immediate response observed in 12 women and all responding by the second dose. Oral doses of 6080 mg/day up to a total dose of 2500 mg gave partial or complete relief from nausea and vomiting in 68 patients; an additional 10 patients required oral plus injectable pyridoxine (61). A success rate of 95% was claimed in a study of 62 women treated with a combination of pyridoxine and suprarenal cortex (adrenal cortex extract) (62). None of the preceding six studies was double-blind or controlled. The effect of pyridoxine on blood urea concentrations in hyperemesis has been investigated (63). Blood urea was decreased below normal adult levels in pregnant women and even lower in patients with hyperemesis. Pyridoxine, 40 mg/day orally for 3 days, significantly increased blood urea only in women with hyperemesis. In another measure of the effect of pyridoxine on hyperemesis, elevated serum glutamic acid levels observed with this condition were returned to normal pregnant values after pyridoxine therapy (64). However, another investigator could not demonstrate any value from pyridoxine therapy in 16 patients (65). Placebos were used but the study was not blinded. In addition, only 1 of 16 patients had hyperemesis gravidarum with the remaining 15 presenting with lesser degrees of nausea and vomiting. Based on the above studies, it is impossible to judge the effectiveness of the vitamin in allaying true hyperemesis gravidarum. More than likely, the effect of hydration, possibly improved prenatal care, the attention of health care personnel, the transitory nature of hyperemesis, the lack of strict diagnostic criteria in classifying patients with the disease, and other factors were involved in the reversal of the symptoms of the women involved in these studies. The vitamin, however, does appear to reduce nausea and vomiting of pregnancy as demonstrated in the two investigations described below.

Two studies have demonstrated that oral doses of pyridoxine are effective in alleviating nausea and vomiting of pregnancy (66,67 and 68). A randomized, double-blind, placebo-controlled study that first appeared in abstract form (66), then as a full report (67), found that pyridoxine, 25 mg orally every 8 hours for 72 hours, administered to 31 women at a mean gestational age of 9.3 weeks, significantly reduced severe nausea (p<0.01) and vomiting (p<0.05) of pregnancy. A second study, conducted in a similar manner, using pyridoxine 10 mg orally every 8 hours for 5 days in 167 women at a mean gestational age of 10.9 weeks, also produced a significant reduction in nausea (p=0.0008) and nearly a significant decrease in the number of vomiting episodes (p=0.0552) (68).

A recent case report suggested a link between high doses of pyridoxine and phocomelia (69). The mother, who weighed only 47 kg, took 50 mg of pyridoxine daily plus unknown doses of lecithin and vitamin B12 through the first 7 months of pregnancy. The full-term female infant was born with a near-total amelia of her left leg at the knee. A relationship between any of the drugs and the defect is doubtful.

The combination of doxylamine and pyridoxine (Bendectin, others) has been the focus of considerable debate in the past. The debate centered on whether the preparation was teratogenic. The combination had been used by millions of women for pregnancy-induced nausea and vomiting but was removed from the market by the manufacturer because of a number of large legal awards against the company. Jury decisions notwithstanding, the available scientific evidence indicates the combination is not teratogenic (see Doxylamine).

Among miscellaneous effects, two studies were unable to associate low maternal concentrations of pyridoxine with premature labor (29,43). Similarly, no correlation was found between low levels and stillbirths (10,40). However, 1-minute Apgar scores were significantly related to low maternal and newborn pyridoxine concentrations (14,70). The effects of pyridoxine supplementation in black pregnant women have been studied (71). Lower maternal serum lipid, fetal weight, and placental weight, and the frequency of placental vascular sclerosis were observed. Others have not found a correlation between pyridoxine levels and birth weight (15,43,70). In an unusual report, pregnant women given daily 20-mg supplements of pyridoxine by either lozenges or capsules had less dental disease than untreated controls (72). The best cariostatic effect was seen in patients in the lozenge group.

In summary, pyridoxine deficiency during pregnancy is a common problem in unsupplemented women. Supplementation with oral pyridoxine reduces but does not eliminate the frequency of deficiency. No definitive evidence has appeared that indicates mild to moderate deficiency of this vitamin is a cause of maternal or fetal complications. Most of the studies with this vitamin have been open and uncontrolled. If a relationship does exist with poor pregnancy outcome, it is probable that a number of factors, of which pyridoxine may be one, contribute to the problem. A significant reduction in nausea and vomiting of pregnancy, however, appears to occur with pyridoxine.

Severe deficiency or abnormal metabolism is related to fetal and infantile convulsions and possibly to other conditions. High doses apparently pose little risk to the fetus. The available evidence does not support a teratogenic risk either alone or in combination with doxylamine. Double-blind, randomized trials are needed to determine whether pyridoxine is effective for severe nausea and vomiting of pregnancy.

Because pyridoxine is required for good maternal and fetal health, and an increased demand for the vitamin occurs during pregnancy, supplementation of the pregnant woman with the RDA for pyridoxine is recommended.

Breast Feeding Summary

Pyridoxine (vitamin B6) is excreted in human breast milk (14,73,74,75,76,77,78 and 79). Concentrations in milk are directly proportional to intake (73,74,75,76,77,78 and 79). In well-nourished women, pyridoxine levels varied, depending on intake, from 123 to 314 ng/mL (73,74 and 75). Peak pyridoxine milk levels occurred 38 hours after ingestion of a vitamin supplement (73,75,76). A 1983 study measured pyridoxine levels in pooled human milk obtained from preterm (26 mothers: 2934 weeks) and term (35 mothers: 39 weeks or longer) patients (77). Levels in milk obtained from preterm mothers rose from 11.1 ng/mL (colostrum) to 62.2 ng/mL (16196 days), whereas levels in milk from term mothers increased during the same period from 17.0 to 107.1 ng/mL. In a 1985 study, daily supplements of 020 mg resulted in milk concentrations of 93413 ng/mL, corresponding to an infant intake of 0.060.28 mg/day (76). A significant correlation was found between maternal intake and infant intake. Most infants, however, did not receive the RDA for infants (0.3 mg) even when the mother was consuming 8 times the RDA for lactating women (2.5 mg) (76). In lactating women with low nutritional status, supplementation with pyridoxine, 0.440.0 mg/day, resulted in mean milk concentrations of 80158 ng/mL (78).

Convulsions have been reported in infants fed a pyridoxine-deficient diet (see discussion under Fetal Risk Summary) (48,49,50,51,52 and 53). Seizures were described in two breast-fed infants, one of whom was receiving only 67 g/day in the milk (80). Intake in the second infant was not determined. A similar report involved three infants whose mothers had levels less than 20 ng/mL (at 7 days postpartum) or less than 60 ng/mL (at 4 weeks) of pyridoxine in their milk (81). The convulsions responded promptly to B6 therapy in all five of these infants.

Very large doses of pyridoxine have been reported to have a lactation-inhibiting effect (82). Using oral doses of 600 mg/day, lactation was successfully inhibited in 95% of patients within 1 week as compared with only 17% of placebo-treated controls. Very high IV doses of pyridoxine, 600 mg infused for 1 hour in healthy, nonlactating young adults, successfully suppressed the rise in prolactin induced by exercise (83). However, because use of this dose and method of administration in lactating women would be unusual, the relevance of these data to breast feeding is limited. With dosage much closer to physiologic levels, such as 20 mg/day, no effect on lactation has been observed (76). In addition, two separate trials, using 450 mg and 600 mg/day in divided oral doses, failed to reproduce the lactation-inhibiting effect observed earlier or to show any suppression of serum prolactin levels (84,85). One writer, however, has suggested that pyridoxine be removed from multivitamin supplements intended for lactating women (86). This proposal has invoked sharp opposition from other correspondents who claimed the available evidence does not support a milk-inhibiting property for pyridoxine (87,88). Moreover, a study published in 1985 examined the effects of pyridoxine supplements, 0.5 or 4.0 mg/day started 24 hours after delivery, on lactation (89). Women receiving the higher dose of pyridoxine had significantly higher concentrations of plasma pyridoxal phosphate (p<0.01) and milk total vitamin B6 (p<0.05) at 1, 3, 6, and 9 months. Plasma prolactin concentrations were similar between the two groups throughout the study. The American Academy of Pediatrics considers pyridoxine to be compatible with breast feeding (90).

In summary, the National Academy of Sciences' RDA for pyridoxine during lactation is 2.1 mg (1). If the diet of the lactating woman adequately supplies this amount, maternal supplementation with pyridoxine is not required (79). Supplementation with the RDA for pyridoxine is recommended for those women with inadequate nutritional intake.

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Questions and Answers

what is the deference between Pyridoxine and pyridoxine hydrochloride?,

HCl (hydrochloride) is added to make the drug water-soluble and to also help the body absorb it. They're almost identical, from a pharmacological standpoint.

What can i write about Pyridoxine Hydrochloride?, maybe some small little help can help me thanks for anything

google it, I'm sure you can get answers from there

Mecobalamn Folic Acid &Pyridoxine hydrochloride which group of medicine and what purpose does it used?,

Folic Acid is used in prenatel vitamens.

Hi, i have recently started taking pyridoxine a B6 vitamin to help my pms but...?, but im late on my period my a week.. has it affected it... i started i think like 2 days after my last period but now ive not come on... Im 15 btw x and have been on my periods 13 months now...

I hardly doubt the B6 would have any affect whatsoever. Vitamins are supposed to be a way a supplementing what your diet is lacking..and if you started eating differently or more healthy that would not affect the cycle either...it may affect how you feel...but not the cycle itself.

Of course I suppose there are exceptions to anything...but I'm sure it has to do with stress and the fact that you are young and still establishing some regularity...takes quite some time for some. Always can call doctors office and ask to talk to a nurse or a pharmacist at any nearby drugstore or pharmacy too.

i went the doctors and he prescribed me pyridoxine dey said it wil calm me down... Is it sort of a adhd tablet?, because i said is it some sort of adhd and he said There is some possibility and he said we will give pyridoxine for now and after Christmas he said come back so he can see how i am doing.... ? :)

Pydidoxine is just a form of vitamin B6. Don't think it has any role in ADHD, however.

what is the use of medicines named r-cine's&cumbotol&pyridoxine?, just medicines

these are the medicines used for tuberculosis.

What is Pyridoxine?, I need to know its chemical formula. If it is an acid,base or neutral. If it is an element,compound, or mixture. If it is a solid, liquid, or gas. Also if it is organic or inorganic.

vitamin B6 as it is also known. 5 forms exist.
a water soluble enzyme, white or off-white powder, slightly yellow when diluted in water.
slightly basic PKa=8.37
chemical formula:C8H11NO3
a compound
organic, found in turkey drumsticks, potatoes with skins, beef liver, etc...

how much do other tablets affect the efficiency of the pill?, my best friend is on pyridoxine (viatmin B6) for a neurological disorder and also the contraceptive pill. it says that it makes the pill less efficient but how much less?

I can't tell you about B6 myself but here is what I found also it might requires a lot of research but here are some sites that deal with combination of contraceptives and other medication

http://www.sopharma.com/vitamin_b6.phtml
http://www.thehormoneshop.com/progestero...
http://dan.xtend-life.com/ingredients/vi...
http://pages.prodigy.net/naturedoctor/vi...
http://www.viagra-vitamins.com/Drugs/Con...

http://www.femalepatient.com/html/arc/si...
http://www.mediresource.com/sdm/sdm/engl...
http://www.aemj.org/cgi/content/full/7/8...
http://www.answers.com/topic/drug-metabo...