Mosby's 2014 Nursing Drug Reference (243 page)

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

liothyronine (T
3
) (Rx)

(lye-oh-thye′roe-neen)

Cytomel, Triostat

Func. class.:
Thyroid hormone

Chem. class.:
Synthetic T
3

Do not confuse:
Cytomel
/Cytotec

ACTION:

Increases metabolic rates, cardiac output, O
2
consumption, body temp, blood volume, growth, development at cellular level; exact mechanism unknown

USES:

Hypothyroidism, myxedema coma, thyroid hormone replacement, congenital hypothyroidism, nontoxic goiter, T
3
suppression test

CONTRAINDICATIONS:

Adrenal insufficiency, MI, thyrotoxicosis, untreated hypertension

 

Black Box Warning:

Obesity treatment

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

DOSAGE AND ROUTES
Calculator

• Adult:
PO
25 mcg/day, increase by 12.5-25 mcg q1-2wk until desired response, maintenance dose 25-75 mcg/day, max 100 mcg/day

• Geriatric:
PO
5 mcg/day, increase by 5 mcg/day q1-2wk, maintenance 25-75 mcg/day

Congenital hypothyroidism

• Child >3 yr:
PO
50-100 mcg/day

• Child <3 yr:
PO
5 mcg/day, increase by 5 mcg q3-4days titrated to response, infant maintenance 20 mcg/day; 1-3 yr 50 mcg/day

Myxedema, severe hypothyroidism

• Adult:
PO
25-50 mcg then may increase by 5-10 mcg q1-2wk; maintenance dose 50-100 mcg/day

Myxedema coma/precoma

• Adult:
IV
25-50 mcg initially, 5 mcg in geriatric patients, 10-20 mcg with cardiac disease; give doses q4-12hr

Nontoxic goiter

• Adult:
PO
5 mcg/day, increase by 12.5-25 mcg q1-2wk; maintenance dose 75 mcg/day

Suppression test

• Adult:
PO
75-100 mcg/day × 1 wk; radioactive
131
I given before and after 1-wk dose

Available forms:
Tabs 5, 25, 50 mcg; inj 10 mcg/ml

Administer:

• 
In
AM
if possible as a single dose to decrease sleeplessness

• 
At same time each day to maintain product level

• 
Only for hormone imbalances; do not use for obesity, male infertility, menstrual conditions, lethargy

• 
Lowest dose that relieves symptoms

• 
Liothyronine after discontinuing other thyroid preparations

• 
Do not give with calcium, iron, aluminum, magnesium, soy products

SIDE EFFECTS

CNS:
Insomnia, tremors
, headache,
thyroid storm

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

PHARMACOKINETICS

PO/IV:
Peak 2-3 days, duration 72 hr, half-life 2.5 days

INTERACTIONS

Increase:
effects of—anticoagulants, sympathomimetics, tricyclics, amphetamines, decongestants, vasopressors

Decrease:
absorption of liothyronine—cholestyramine; colestipol; calcium, iron, aluminum, magnesium products

Decrease:
effects of liothyronine—estrogens

Drug/Herb

Decrease:
thyroid hormone effect—soy

Drug/Lab Test

Increase:
CPK, LDH, AST, PBI, 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
, 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:

• 
Removal 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; paresthesia; syncope, stupor, coma

Teach patient/family:

• 
That hair loss will occur in child but is temporary

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

• 
Not to switch brands unless approved by prescriber

• 
That hypothyroid child will show almost immediate behavior/personality change

• 
That product is not to be taken to reduce weight

• 
To avoid OTC preparations with iodine; to read labels; not to take with calcium, iron, aluminum, magnesium products

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

• 
That product controls symptoms but does not cure; that treatment is lifelong

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

liotrix (Rx)

(lye′oh-trix)

Thyrolar, T
3
/T
4

Func. class.:
Thyroid hormone

Chem. class.:
Levothyroxine/liothyronine (synthetic T
4
, T
3
)

Do not confuse:
Thyrolar
/Thyrar

ACTION:

Increases metabolic rates, cardiac output, O
2
consumption, body temp, blood volume, growth, development at cellular level; exact mechanism unknown

USES:

Hypothyroidism, thyroid hormone replacement

CONTRAINDICATIONS:

Adrenal insufficiency, MI, thyrotoxicosis

 

Black Box Warning:

Obesity treatment

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

DOSAGE AND ROUTES
Calculator

• Adult:
PO
single dose of Thyrolar, 1/4 or 1/2 of adult dose, adjust as needed at 2-wk intervals

• Geriatric:
PO
1/4 tab initially, adjust q6-8wk

Available forms:
Tabs: Levothyroxine 12.5 mcg/liothyronine 3.1 mcg; levothyroxine 25 mcg/liothyronine 6.25 mcg (Thyrolar-1/2); levothyroxine 50 mcg/liothyronine 12.5 mcg (Thyrolar-1); levothyroxine 100 mcg/liothyronine 25 mcg (Thyrolar-2); levothyroxine 150 mcg/liothyronine 37.5 mcg (Thyrolar-3)

Administer:

• 
Separate products containing calcium, iron by ≥4 hr

• 
In
AM
if possible as a single dose to decrease sleeplessness

• 
At same time each day to maintain product level

• 
Only for hormone imbalances; do not use for obesity, male infertility, menstrual conditions, lethargy

• 
Lowest dose that relieves symptoms

SIDE EFFECTS

CNS:
Insomnia, tremors
, headache,
thyroid storm,
nervousness

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

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

MISC:
Menstrual irregularities, weight loss, sweating, heat intolerance, fever

PHARMACOKINETICS

PO (T
4
):
Onset unknown, peak 1-3 wk, duration 1-3 wk, terminal half-life 6-7 days

PO (T
3
):
Onset unknown, peak 24-72 hr, duration 72 hr, terminal half-life 1-2 days

INTERACTIONS

Increase:
effects of amphetamines, decongestants, vasopressors, anticoagulants, sympathomimetics, tricyclics, catecholamines

Decrease:
absorption of liotrix—cholestyramine, colestipol

Decrease:
effects of liotrix—estrogens, phenytoin, carBAMazepine, rifampin

Drug/Herb

Decrease:
thyroid hormone effect—soy

Drug/Lab Test

Increase:
CPK, LDH, AST, PBI, 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 is receiving too low a dose of medication

• 
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:

• 
Withdrawal of medication 4 wk before RAIU test

• 
Storage in airtight, light-resistant container

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; coarse hair; menorrhagia; night blindness; paresthesias; syncope, stupor, coma; rosy cheeks

Teach patient/family:

• 
That hair loss will occur in child, is temporary

• 
To report excitability, irritability, chest pain, increased pulse rate, palpitations, excessive sweating, heat intolerance, nervousness, anxiety, which indicate overdose

• 
Not to switch brands unless approved by prescriber

• 
That hypothyroid child will show almost immediate behavior/personality change

• 
That product is not to be taken to reduce weight

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

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

• 
That product does not cure but controls symptoms; treatment is lifelong

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