Mosby's 2014 Nursing Drug Reference (232 page)

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

lamiVUDine 3TC (Rx)

(lam-i-voo′deen)

Epivir, Epivir HBV

Func. class.:
Antiretroviral

Chem. class.:
Nucleoside reverse transcriptase inhibitor (NRTI)

Do not confuse:
lamiVUDine
/lamoTRIgine

ACTION:

Inhibits replication of HIV virus by incorporating into cellular DNA by viral reverse transcriptase, thereby terminating cellular DNA chain

USES:

HIV-1 infection in combination with at least 2 other antiretrovirals; chronic hepatitis B (Epivir-HBV)

Unlabeled uses:
Prophylaxis of HIV: postexposure with indinavir and zidovudine

CONTRAINDICATIONS:

Hypersensitivity

 

Black Box Warning:

Lactic acidosis

Precautions:
Pregnancy (C), breastfeeding, children, geriatric patients, granulocyte count <1000/mm
3
or Hgb <9.5 g/dl, renal disease, pancreatitis, peripheral neuropathy

 

Black Box Warning:

Severe hepatic dysfunction

DOSAGE AND ROUTES
Calculator
HIV

• Adult and adolescent >16 yr:
PO
150 mg bid or 300 mg/day

• Child 3 mo-16 yr:
PO
4 mg/kg bid, max 150 mg bid

Chronic hepatitis B

• Adult:
PO
100 mg/day

• Child and adolescent 2-17 yr:
PO
3 mg/kg/day, max 100 mg

Renal dose

• Adult:
PO
CCr 30-49 ml/min: Epivir 150 mg/day; Epivir HBV 100 mg 1st dose then 50 mg/day; CCr 15-29 ml/min: Epivir 150 mg 1st dose then 100 mg/day; Epivir HBV 100 mg 1st dose then 25 mg/day; CCr 5-14 ml/min: Epivir 150 mg 1st dose then 50 mg/day; Epivir HBV 35 mg 1st dose then 15 mg/day; CCr <5 ml/min: Epivir 50 mg 1st dose then 25 mg/day; Epivir HBV 35 mg 1st dose then 10 mg/day

Available forms:
(Epivir)
oral sol 10 mg/ml; tabs 150, 300 mg; (
Epivir HBV
) oral sol 5 mg/ml; tabs 100 mg

Administer:

• 
PO daily or bid, without regard to meals

• 
Epivir and Epivir HBV are not interchangeable

• 
With other antiretrovirals only

SIDE EFFECTS

CNS:
Fever, headache, malaise, dizziness, insomnia, depression, fatigue, chills
,
seizures,
peripheral neuropathy, paresthesias

EENT:
Taste change, hearing loss, photophobia

GI:
Nausea, vomiting, diarrhea
, anorexia, cramps, dyspepsia,
hepatomegaly with steatosis, pancreatitis

HEMA:
Neutropenia, anemia, thrombocytopenia

INTEG:
Rash

MS:
Myalgia, arthralgia, pain

RESP:
Cough

SYST:
Lactic acidosis, anaphylaxis, Stevens-Johnson syndrome

PHARMACOKINETICS

Rapidly absorbed, distributed to extravascular space, excreted unchanged in urine, protein binding <36%, terminal half-life 5-7 hr

INTERACTIONS

Decrease:
both products—zalcitabine; avoid concurrent use

Increase:
lamiVUDine level—trimethoprim-sulfamethoxazole, amiloride, dofetilide, entecavir, metformin, memantine, procainamide, trospium

• 
Do not use with emtricitabine, duplication

Decrease:
lamiVUDine effect—interferons

Drug/Lab Test

Increase:
ALT, bilirubin

Decrease:
Hgb, neutrophil, platelet count

NURSING CONSIDERATIONS
Assess:

• 
HIV:
Test for HIV before starting treatment, blood counts q2wk; watch for neutropenia, thrombocytopenia, Hgb, CD4, viral load; if low, therapy may have to be discontinued and restarted after hematologic recovery; blood transfusions may be required; assess for lessening of symptoms; if HBV is present, a higher dose of Epivir-HBV is needed

• 
Hepatitis B:
fatigue, anorexia, pruritus, jaundice during and for several months after discontinuation; AST, ALT, bilirubin; amylase, lipase, triglycerides, periodically during treatment

• 
Children for pancreatitis:
abdominal pain, nausea, vomiting, neuropathy

 

Black Box Warning:

Lactic acidosis, severe hepatomegaly with steatosis: obtain baseline LFTs, if elevated, discontinue treatment; discontinue even if LFTs are normal if lactic acidosis, severe hepatomegaly develops, may be fatal

Perform/provide:

• 
Storage in cool environment; protect from light

Evaluate:

• 
Decreasing symptoms of HIV, CD4, viral load

Teach patient/family:

• 
That GI complaints, insomnia resolve after 3-4 wk of treatment

• 
That product is not a cure for HIV but will control symptoms; that compliance is necessary; to take as directed; to complete full course of treatment even if feeling better

• 
To notify prescriber of sore throat, swollen lymph nodes, malaise, fever, peripheral neuropathy; other infections may occur

• 
That patient is still infective, may pass HIV virus on to others

• 
That follow-up visits must be continued since serious toxicity may occur; that blood counts must be done

• 
That other products may be necessary to prevent other infections

• 
That product may cause fainting or dizziness

• 
Not to breastfeed, excreted in breast milk

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

lamoTRIgine (Rx)

(la-moe′tri-geen)

LaMICtal, LaMICtal CD, LaMICtal ODT, LaMICtal XR

Func. class.:
Anticonvulsant—miscellaneous

Chem. class.:
Phenyltriazine

Do not confuse:
lamoTRIgine
/lamiVUDine
LaMICtal
/Lomotil/LamISIL

ACTION:

Inhibits voltage-sensitive sodium channels, thus decreasing seizures

USES:

Adjunct for the treatment of partial, tonic-clonic seizures; children with Lennox-Gastaut syndrome, bipolar disorder

Unlabeled uses:
Absence, seizures

CONTRAINDICATIONS:

Hypersensitivity

Precautions:
Pregnancy (C) (cleft lip/palate during 1st trimester), breastfeeding, geriatric patients, cardiac/renal/hepatic disease, severe depression, suicidal, blood dyscrasias

 

Black Box Warning:

Children <16 yr

DOSAGE AND ROUTES
Calculator
Seizures: monotherapy

• Adult and adolescent ≥16 yr:
PO
50 mg/day while receiving 1 enzyme-inducing AED (carBAMazepine, PHENobarbital, phenytoin, primidone but not valproic acid) wk 1-2, then increase to 100 mg divided bid wk 3-4; maintenance 300-500 mg/day; EXT REL 50 mg/day × 1-2 wk, then 100 mg/day wk 3-4, then 200 mg/day wk 5, then 300 mg/day wk 6, then 400 mg/day wk 7; after wk 7, range is 400-600 mg/day

• Adolescent <16 yr and child:
PO
0.3 mg/kg/day wk 1-2, then 0.6 mg/kg/day wk 3-4; depends on use of AED; usual dose 4.5-7.5 mg/kg/day, max 300 mg/day

Monotherapy for patients taking valproate

• Adult and adolescent ≥16 yr receiving lamotrigine and valproate without enzyme-inducing drug:
PO
(immediate release) stabilize on valproate, target dose of 200 mg/day lamoTRIgine; if patient is not taking lamoTRIgine 200 mg/day, increase dose by 25-50 mg/day q1-2wk to reach 200 mg/day; while maintaining lamoTRIgine 200 mg/day, decrease valproate to 500 mg/day by ≤500 mg/day/wk, maintain valproate at 500 mg/day × 1 wk, then increase lamoTRIgine to 300 mg/day while decreasing valproate 250 mg/day × 1 wk, then discontinue valproate and increase lamoTRIgine by 100 mg/day/wk to maintenance of 500 mg/day

Seizures: Multiple therapy with valproate

• Adult and adolescent ≥16 yr:
PO
25 mg every other day then 25 mg/day wk 3-4, increase by 25-50 mg q1-2wk, maintenance 100-400 mg/day

• Adolescent <16 yr and child:
PO
0.1-0.2 mg/kg/day initially then increase q2wk as needed to 1-5 mg/kg/day or 200 mg/day

Bipolar disorder (escalation regimen for those not taking carbamazepine, other enzyme-inducing drugs, or valproate)

• Adult and adolescent ≥16 yr:
PO
wk 1-2, 25 mg/day; wk 3-4, 50 mg/day; wk 5, 100 mg/day; wk 6-7, 200 mg/day; for patients taking valproic acid: wk 1-2, 25 mg every other day; wk 3-4, 25 mg/day; wk 5, 50 mg/day; wk 6, 100 mg/day; wk 7, 100 mg/day

Hepatic dose

• Adult:
PO
moderate hepatic impairment or severe without ascites: reduce by 25%; severe hepatic impairment with ascites: reduce by 50%

Absence seizures (unlabeled)

• Adolescent and child 3-13 yr:
PO
0.5 mg/kg/day in 2 divided doses × 2 wk then 1 mg/kg/day in 2 divided doses × 2 wk, adjusted q5days

Available forms:
Tabs 25, 100, 150, 200 mg; PO ext rel 25-50-100, 50-100-200 mg titration kit; PO 25-100 mg starter kit; ext rel 25, 50, 100, 250 mg; chew dispersible tabs 5, 25 mg; oral disintegrating tab 25, 50, 100, 200 mg; oral disintegrating tab 25-50, 50-100 mg, 25-50-100 mg titration kit

Administer:

• 
Correct starter kit; errors have occurred

• 
Discontinue all products gradually over ≥2 wk; abrupt discontinuation can increase seizures

• 
Chewable dispersible tab:
may be swallowed whole, chewed, mixed in water or fruit juice; to mix, add to small amount of liquid in glass or spoon; tabs will dissolve in 1 min, then mix in more liquid and swirl and swallow immediately

• 
Orally disintegrating tabs:
place on tongue, move around in mouth, when disintegrated, swallow; examine blister pack before use, do not use if blisters are torn or missing

• 
Extended-release tabs:
swallow whole, do not cut, break, chew; without regard to food

SIDE EFFECTS

CNS:
Dizziness
, ataxia,
headache
, fever, insomnia, tremor, depression, anxiety,
suicidal ideation

EENT:
Nystagmus,
diplopia, blurred vision

GI:
Nausea, vomiting, anorexia, abdominal pain
,
hepatotoxicity

GU:
Dysmenorrhea

HEMA:
Anemia,
DIC, leukopenia, thrombocytopenia

INTEG:
Rash (potentially life-threatening),
alopecia, photosensitivity

SYST:
Stevens-Johnson syndrome, angioedema, toxic epidermal necrolysis

PHARMACOKINETICS

Half-life varies depending on dose; terminal half-life 24 hr, 15 hr with enzyme inducers; rapidly, completely absorbed; metabolized by glucuronic acid conjunction; protein binding 55%; peak 1.4-2.3 hr; crosses placenta; excreted in breast milk

INTERACTIONS

Decrease:
metabolic clearance of lamoTRIgine—valproic acid, CYP3A4 inhibitors

Decrease:
lamoTRIgine concentration—carBAMazepine, rifamycins, oral contraceptives, acetaminophen, phenytoin, primodone, PHENobarbital, OXcarbazepine, succinimides, estrogen

Drug/Herb

Increase:
anticonvulsant effect—ginkgo

Decrease:
anticonvulsant effect—ginseng

NURSING CONSIDERATIONS
Assess:

• 
Seizure:
duration, type, intensity, halo before seizure

 
Rash (Stevens-Johnson syndrome, toxic epidermal necrolysis) in pediatric patients; product should be discontinued at first sign of rash

 
Bipolar disorder:
suicidal thoughts/behaviors

Evaluate:

• 
Therapeutic response: decrease in severity of seizures or of bipolar symptoms

Teach patient/family:

• 
To take PO doses divided, with or after meals to decrease adverse effects; not to discontinue product abruptly because seizures may occur

• 
To avoid hazardous activities until stabilized on product

• 
To carry emergency ID; to notify prescriber of skin rash, increased seizure activity; to use sunscreen, protective clothing if photosensitivity occurs

• 
To notify prescriber if pregnant, intending to become pregnant

• 
To notify prescriber immediately of suicidal thoughts/behaviors

• 
To notify prescriber if pregnancy is planned or suspected, pregnancy (C), product decreases folate, avoid breastfeeding

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