Intravenous pyridoxine-induced metabolic acidosis.
OBJECTIVE
Pyridoxine hydrochloride, the antidote for isonicotinic acid hydrazide (INH)--induced seizures, is available in solution at a concentration of 100 mg/mL at a pH of less than 3. Pyridoxine is often infused rapidly in large doses for INH-induced seizures. Effects of pyridoxine infusion on base deficit in amounts given for INH poisoning have not been studied in human subjects. We hypothesized that this infusion would result in transient worsening of acidosis.


METHODS
We conducted a randomized, controlled crossover trial in human volunteers. Five healthy volunteers (mean age, 35 years; range, 29 to 43 years) were randomized to receive intravenous placebo (50 mL of normal saline solution) or 5 g of pyridoxine (50 mL) over 5 minutes. A peripheral intravenous catheter was established in each arm, and a heparinized venous blood sample was obtained for base deficit at baseline and 3, 6, 10, 20, and 30 minutes after infusion. After at least a 1-week washout period, the volunteers were assigned to the alternate arms of the experiments, thus acting as their own control subjects. Data were analyzed by using the 2-tailed paired t test, controlling for multiple comparisons.


RESULTS
No difference was noted between groups at baseline. A statistically significant increased base deficit was noted after the pyridoxine infusion versus control at 3 to 20 minutes but not at 30 minutes (P =.1). Maximal mean increase in base deficit (2.74 mEq/L) was noted at 3 minutes.


CONCLUSIONS
A transient increase in base deficit occurs after the infusion of 5 g of pyridoxine in normal volunteers.
Lovecchio
F
F
Department of Medical Toxicology, Good Samaritan Regional Medical Center, Phoenix, AZ, USA. Frank.Lovecchio@Bannerhealth.org
Curry
S C
SC
Graeme
K A
KA
Wallace
K L
KL
Suchard
J
J
D000138:Acidosis / Q000097:blood / Q000139:chemically induced* / Q000175:diagnosis; D000328:Adult; D000931:Antidotes / Q000009:adverse effects*; D000995:Antitubercular Agents / Q000009:adverse effects*; D001784:Blood Gas Analysis; D018592:Cross-Over Studies; D016903:Drug Monitoring; D006801:Humans; D007262:Infusions, Intravenous; D007538:Isoniazid / Q000009:adverse effects*; D011736:Pyridoxine / Q000009:adverse effects*; D012640:Seizures / Q000139:chemically induced* / Q000188:drug therapy*; D013997:Time Factors
D000931:Antidotes; D000995:Antitubercular Agents; D011736:Pyridoxine; D007538:Isoniazid