Mosby's 2014 Nursing Drug Reference (339 page)

pyridoxine (vit B
6
) (Rx,
OTC
)

(peer-i-dox′een)

Equaline Vitamin B6, Neuro-K, Walgreens Finest B-6, Walgreens Gold Seal Vitamin B6

Func. class.:
Vit B
6
, water soluble

ACTION:

Needed for fat, protein, carbohydrate metabolism; enhances glycogen release from liver and muscle tissue; needed as coenzyme for metabolic transformations of a variety of amino acids

USES:

Vit B
6
deficiency of inborn errors of metabolism, seizures, isoniazid therapy, oral contraceptives, alcoholic polyneuritis

Unlabeled uses:
Palmar-plantar erythrodysesthesia syndrome

CONTRAINDICATIONS:

Hypersensitivity

Precautions:
Pregnancy (A), breastfeeding, children, Parkinson’s disease; patients taking levodopa should avoid supplemental vitamins with >5 mg pyridoxine

DOSAGE AND ROUTES
Calculator
RDA

• Adult:
PO
(male) 1.7-2 mg; (female) 1.4-1.6 mg

• Child 9-13 yr:
PO
1 mg/day

• Child 4-8 yr:
PO
0.6 mg/day

• Child 1-3 yr:
PO
0.5 mg/day

• Infant 7-12 mo:
PO
0.3 mg/day

Vit B
6
deficiency

• Adult:
PO
5-25 mg/day × 3 wk

• Child:
PO
10 mg until desired response

Pyridoxine deficiency neuritis/seizure (not drug induced)

• Adult:
PO
without neuritis
2.5-10 mg/day after corrected 2-5 mg/day;
with neuritis
100-200 mg/day × 3wk then 2-5 mg/day

• Child:
PO
without neuritis
5-25 mg/day × 3wk then 1.5-2.5 mg/day in a multivitamin;
with neuritis:
10-50 mg/day × 3wk then 1-2 mg/day

• Neonate with seizures:
IM/IV
50-100 mg as single dose

Deficiency caused by isoniazid, cycloserine, hydralazine, penicillamine

• Adult:
PO
100-300 mg/day

• Child:
PO
10-50 mg/day

Prevention of deficiency caused by isoniazid, cycloserine, hydralazine, penicillamine

• Adult:
PO
25-100 mg/day

• Child:
PO
1-2 mg/kg/day

Palmar-plantar erythrodysesthesia syndrome (unlabeled)

• Adult:
PO
50-150 mg/day

Available forms:
Tabs 10, 25, 50, 100 mg; ext rel tabs 100 mg; inj 100 mg/ml; ext rel caps 150 mg

Administer:
PO route

• 
Do not break, crush, or chew ext rel tabs/caps

IM route

• 
Rotate sites; burning or stinging at site may occur

• 
Z
-track to minimize pain

IV route

• 
Undiluted or added to most IV sol; give ≤50 mg/1 min if undiluted

Syringe compatibilities:
Doxapram

SIDE EFFECTS

CNS:
Paresthesia, flushing, warmth, lethargy (rare with normal renal function)

INTEG:
Pain at inj site

PHARMACOKINETICS

PO/INJ:
Half-life 2-3 wk, metabolized in liver, excreted in urine

INTERACTIONS

Decrease:
effects of levodopa

Decrease:
effects of pyridoxine—oral contraceptives, isoniazid, cycloSERINE, hydrALAZINE, penicillamine, chloramphenicol, immunosuppressants

NURSING CONSIDERATIONS
Assess:

• 
Pyridoxine deficiency:
seizures, irritability, cheilitis, conjunctivitis, anemia, confusion, red tongue, weakness, fatigue prior to and during treatment; monitor pyridoxine levels

• 
Nutritional status: yeast, liver, legumes, bananas, green vegetables, whole grains

• 
Blood studies: Hct, Hgb

Perform/provide:

• 
Storage in tight, light-resistant container

Evaluate:

• 
Therapeutic response: absence of nausea, vomiting, anorexia, skin lesions, glossitis, stomatitis, edema, seizures, restlessness, paresthesia

Teach patient/family:

• 
To avoid vitamin supplements unless directed by prescriber

• 
To increase meat, bananas, potatoes, lima beans, whole grain cereals in diet

• 
To take as directed; to continue with follow-up exams, blood work

Canada only   Side effects:
italics
= common;
bold
= life-threatening   
Nurse Alert

pyrimethamine (Rx)

(peer-i-meth′a-meen)

Daraprim

Func. class.:
Antimalarial, antiprotozoal

Chem. class.:
Folic acid antagonist

ACTION:

Inhibits folic acid metabolism in parasite, prevents transmission by stopping growth of fertilized gametes

USES:

Malaria prophylaxis,
Plasmodium vivax, Pneumocystis jiroveci

Unlabeled uses:
Isosporiasis, pneumocystis pneumonia prophylaxis, toxoplasmic encephalitis prophylaxis

CONTRAINDICATIONS:

Hypersensitivity, chloroquine-resistant malaria, megaloblastic anemia caused by folate deficiency

Precautions:
Pregnancy (C), breastfeeding, geriatric patients, blood dyscrasias, seizure disorder, G6PD disease, renal/hepatic disease

DOSAGE AND ROUTES
Calculator
Prophylaxis of malaria

Begin 2 wk before entering endemic area, continue for 6-10 wk after return

• Adult/child
>
10 yr:
PO
25 mg/wk

• Child 4-10 yr:
PO
12.5 mg/wk

• Child
<
4 yr:
PO
6.25 mg/wk

Malaria treatment

• Adult/adolescent/child
>
10 yr:
PO
25 mg q day × 2 days with a sulfonamide

• Child 4-10 yr:
PO
25 mg/day × 2 days

Toxoplasmosis

• Adult:
PO
50-75 mg, then reduce by about 50% for 4-5 wk with 1-4 g sulfadoxine × 1-3 wk, then reduce by 50% for 4-5 wk

• Child:
PO
1 mg/kg/day in 2 divided doses or 2 mg/kg/day × 3 days then 1 mg/kg/day or divided twice daily × 4 wk, max 25 mg/day

Toxoplasmosis in AIDS patients

• Adult:
PO
100-200 mg/day × 1-2 days, then 50-100 mg/day × 3-6 wk, then 25-50 mg/day for life (given with clindamycin or sulfADIAZINE)

Isosporiasis (unlabeled)

• Adult:
PO
75 mg/day with leucovorin 10 mg/day × 14 days

Available forms:
Tabs 25 mg; combo tabs 500 mg sulfadoxine/25 mg pyrimethamine

Administer:
PO route

• 
Leucovorin IM 3-9 mg/day × 3 days if folic acid deficiency occurs

• 
Before or after meals at same time each day to maintain product level, decrease GI symptoms

• 
Extemporaneous susp:
tabs may be crushed and mixed with 25 ml distilled water, sucrose-containing solution (1 mg/ml); shake well, stable for 5-7 days at room temperature if mixed with sucrose-containing solutions

SIDE EFFECTS

CNS:
Stimulation, irritability,
seizures,
tremors, ataxia, fatigue, fever

CV:
Dysrhythmias

GI:
Nausea, vomiting, cramps, anorexia
, diarrhea, atrophic glossitis, gastritis

HEMA:
Thrombocytopenia, leukopenia, pancytopenia, megaloblastic anemia,
decreased folic acid,
agranulocytosis

INTEG:
Skin eruptions, photosensitivity,
Stevens-Johnson syndrome

RESP:
Respiratory failure

PHARMACOKINETICS

PO:
Peak 2 hr, half-life 96 hr, half-life accelerated to 23 hr in AIDS patients, metabolized in liver, highly protein bound, excreted in urine (metabolites)

INTERACTIONS

• 
Synergistic action: folic acid

Increase:
Megaloblastic anemia risk, agranulocytosis, thrombocytopenia—zidovudine

Increase:
bone marrow suppression—bone marrow depressants, folate antagonists, radiation therapy

NURSING CONSIDERATIONS
Assess:

• 
Folic acid level; megaloblastic anemia occurs

 
Blood dyscrasias:
blood studies, CBC, platelets; 2×/wk if dosage is increased

 
Toxicity:
vomiting, anorexia, seizure, blood dyscrasia, glossitis; product should be discontinued immediately

• 
Serious skin disorders:
Stevens-Johnson syndrome (swelling of face, lips, throat, fever)

Perform/provide:

• 
Storage in tight, light-resistant container

Evaluate:

• 
Therapeutic response: decreased symptoms of malaria, toxoplasmosis

Teach patient/family:

• 
To report visual problems, fever, fatigue, bruising, bleeding, sore throat; may indicate
blood dyscrasias

TREATMENT OF OVERDOSE:

Gastric lavage, short-acting barbiturate, leucovorin, respiratory support if needed

Canada only   Side effects:
italics
= common;
bold
= life-threatening   
Nurse Alert

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