Mosby's 2014 Nursing Drug Reference (240 page)

BOOK: Mosby's 2014 Nursing Drug Reference
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Canada only   Side effects:
italics
= common;
bold
= life-threatening   
Nurse Alert

levofloxacin ophthalmic

 

levothyroxine (T
4
) (Rx)

(lee-voe-thye-rox′een)

Eltroxin
, Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid

Func. class.:
Thyroid hormone

Chem. class.:
Levoisomer of thyroxine

Do not confuse:
Synthroid
/Symmetrel

ACTION:

Increases metabolic rate; controls protein synthesis; increases cardiac output, renal blood flow, O
2
consumption, body temp, blood volume, growth, development at cellular level via action on thyroid hormone receptors

USES:

Hypothyroidism, myxedema coma, thyroid hormone replacement, thyrotoxicosis, congenital hypothyroidism, some types of thyroid cancer, pituitary TSH suppression

CONTRAINDICATIONS:

Adrenal insufficiency, recent MI, thyrotoxicosis, hypersensitivity to beef, alcohol intolerance (inj only)

 

Black Box Warning:

Obesity treatment

Precautions:
Pregnancy (A), breastfeeding, geriatric patients, angina pectoris, hypertension, ischemia, cardiac disease, diabetes

DOSAGE AND ROUTES
Calculator
Hypothyroidism

• Adult ≤50 yr:
PO
1.7 mcg/kg/day, 6-8 wk, average dose 100-200 mcg/day; max 200 mcg/day
IM/IV
50-100 mcg/day as single dose or 50% of usual oral dosage

• Adult >50 yr without heart disease or <50 yr with heart disease:
PO
25-50 mcg/day, titrate q6-8wk

• Adult >50 yr with heart disease:
PO
12.5-25 mcg/day, titrate by 12.5-25 mcg q6-8wk

• Child >12 yr:
PO
2-3 mcg/kg/day as single dose in
AM

• Child 6-12 yr:
PO
4-5 mcg/kg/day as single dose in
AM

• Child 1-5 yr:
PO
5-6 mcg/kg/day as single dose in
AM

• Child 6-12 mo:
PO
6-8 mcg/kg/day as single dose in
AM

• Child to 6 mo:
PO
8-10 mcg/kg/day as single dose in
AM

Myxedema coma

• Adult:
IV
200-500 mcg, may increase by 100-300 mcg after 24 hr; give oral medication as soon as possible

Subclinical hypothyroidism

• Adult:
PO
1 mcg/kg/day may be sufficient

Available forms:
Powder for inj 200, 500 mcg/vial; tabs 25, 50, 88, 100, 112, 125, 137, 150, 175, 200, 300 mcg; cap (liquid filled) 13, 25, 50, 75, 88, 100, 112, 125, 137, 150 mcg

Administer:
PO route

• 
In
AM
if possible as single dose to decrease sleeplessness; at same time each day to maintain product level; take on empty stomach

• 
Only for hormone imbalances; not to be used for obesity, male infertility, menstrual conditions, lethargy

• 
Lowest dose that relieves symptoms; lower dose to geriatric patients and for those with cardiac diseases

• 
Crush and mix with water; nonsoy formula or breast milk for infants, children

• 
Separate antacids, iron, calcium products by 4 hr

Direct IV route

• 
IV after diluting with provided diluent 500 mcg/5 ml, 200 mcg/2 ml; shake; give through
Y
-tube or 3-way stopcock; give ≤100 mcg/1 min; do not add to IV inf

• 
Considered to be incompatible in syringe with all other products

SIDE EFFECTS

CNS:
Anxiety, insomnia, tremors
, headache,
thyroid storm,
excitability

CV:
Tachycardia, palpitations, angina, dysrhythmias
, hypertension,
cardiac arrest

GI:
Nausea, diarrhea, increased or decreased appetite, cramps

MISC:
Menstrual irregularities, weight loss, sweating, heat intolerance, fever, alopecia, decreased bone mineral density

PHARMACOKINETICS

Half-life euthyroid 6-7 days, hypothyroid 9-10 days, hyperthyroid 3-4 days, distributed throughout body tissues

PO:
Onset 3-5 days, peak 6-8 wk, duration 1-3 wk

IV:
Onset 6-8 hr, peak 24 hr, duration unknown

INTERACTIONS

Increase:
cardiac insufficiency risk—EPINEPHrine products

Increase:
effects of anticoagulants, sympathomimetics, tricyclics

Decrease:
levothyroxine absorption—bile acid sequestrants, orlistat, ferrous sulfate

Decrease:
levothyroxine effect—estrogens, antacids, sucralfate, aluminum, magnesium, calcium, iron, rifampin, rifabutin

Drug/Herb

Decrease:
thyroid hormone effect—soy

Drug/Lab Test

Increase:
CPK, LDH, AST, blood glucose

Decrease:
thyroid function tests

NURSING CONSIDERATIONS
Assess:

• 
B/P, pulse periodically during treatment

• 
Weight daily in same clothing, using same scale, at same time of day

• 
Height, growth rate of child

• 
T
3
, T
4
, FTIs, which are decreased; radioimmunoassay of TSH, which is increased; radio uptake, which is increased if patient receiving too low a dose of medication

• 
Patient may require decreased anticoagulant; check for bleeding, bruising

• 
Increased nervousness, excitability, irritability, which may indicate too high a dose of medication, usually after 1-3 wk of treatment

• 
Cardiac status: angina, palpitation, chest pain, change in VS

Perform/provide:

• 
Storage in tight, light-resistant container; sol should be discarded if not used immediately

• 
Withdrawal of medication 4 wk before RAIU test

Evaluate:

• 
Therapeutic response: absence of depression; increased weight loss, diuresis, pulse, appetite; absence of constipation, peripheral edema, cold intolerance; pale, cool, dry skin; brittle nails, alopecia, coarse hair, menorrhagia, night blindness, paresthesias, syncope, stupor, coma, rosy cheeks

Teach patient/family:

• 
That hair loss will occur in child, is temporary; that hypothyroid child will show almost immediate behavior/personality change

• 
To report excitability, irritability, anxiety, which indicate overdose

• 
Not to switch brands unless approved by prescriber

• 
That product may be discontinued after giving birth; that thyroid panel should be evaluated after 1-2 mo

• 
That product is not to be taken to reduce weight

• 
To avoid OTC preparations with iodine; to read labels; to separate antacids, iron, calcium products by 4 hr

• 
To avoid iodine-rich food, iodized salt, soybeans, tofu, turnips, high-iodine seafood, some bread

• 
That product is not a cure but controls symptoms; that treatment is lifelong, full effect may take up to 6 wk

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

HIGH ALERT
lidocaine (parenteral) (Rx)

(lye′doe-kane)

LidoPen Auto-Injector, Xylocaine, Xylocard

Func. class.:
Antidysrhythmic (Class Ib)

Chem. class.:
Aminoacyl amide

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