Mosby's 2014 Nursing Drug Reference (412 page)

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

valGANciclovir (Rx)

(val-gan-sy′kloh-veer)

Valcyte

Func. class.:
Antiviral

Chem. class.:
Synthetic nucleoside

Do not confuse:
valGANciclovir
/valACYclovir
Valcyte
/Valtrex

ACTION:

Metabolized to ganciclovir; inhibits replication of human cytomegalovirus in vivo and in vitro by selective inhibition of viral DNA synthesis

USES:

Cytomegalovirus (CMV) retinitis in immunocompromised persons, including those with AIDS, after indirect ophthalmoscopy confirms diagnosis; prevention of CMV with transplantation; prevention of CMV in at-risk patient going through transplant (kidney, heart, pancreas)

Unlabeled uses:
Colitis, Epstein-Barr virus, esophagitis, herpes simplex type 1, 2; human herpesvirus 6, 8; multicentric Castleman’s disease, varicella-zoster virus

CONTRAINDICATIONS:

Breastfeeding, hypersensitivity to ganciclovir, valACYclovir; absolute neutrophil count <500/mm
3
; platelet count <25,000/mm
3
; hemodialysis; liver transplantation

Precautions:
Pregnancy (C), children, geriatric patients, renal function impairment; hypersensitivity to acyclovir, penciclovir, famciclovir

 

Black Box Warning:

Preexisting cytopenias, secondary malignancy, infertility, anemia

DOSAGE AND ROUTES
Calculator
Treatment of CMV

• Adult and adolescent (unlabeled):
PO
induction 900 mg bid × 21 days with food; maintenance 900 mg/day with food

Transplant (CMV prophylaxis)

• Adult/adolescent >16 yr:
PO
900 mg/day with food starting 10 days prior to transplantation until day 100 after transplantation

• Infant ≥4 mo/child/adolescent ≤16 yr:
PO
give within 10 days of heart/kidney transplant; calculate dose as 7 × BSA × CCr, give as single daily dose

Renal dose

• Adult:
PO
CCr ≥60 ml/min, same as above; CCr 40-59 ml/min, 450 mg bid for 21 days then 450 mg/day; CCr 25-39 ml/min, 450 mg/day then 450 mg q2days; CCr 10-24 ml/min, 450 mg q2days then 450 mg 2×/week

Available form:
Tabs 450 mg, powder for oral sol 50 mg/ml

Administer:
PO tab

• 
With food for better absorption; avoid getting product on skin; do not break

Oral sol

• 
Measure 9 ml purified water in graduated cylinder, shake bottle to loosen powder, add 1/2 liquid, shake well, add remaining water, shake; remove child-resistant cap and push bottle adapter into neck of bottle, close with cap, give using dispenser provided

• 
Store liquid in refrigerator; do not freeze; throw away any unused after 49 days

SIDE EFFECTS

CNS:
Fever
, chills,
coma,
confusion
, abnormal thoughts, dizziness, bizarre dreams,
headache, insomnia
, psychosis, tremors, somnolence,
paresthesia, weakness
,
seizures

EENT:
Retinal detachment with CMV retinitis

GI:
Abnormal LFTs,
nausea, vomiting, anorexia, diarrhea, abdominal pain
,
hemorrhage

GU:
Hematuria,
increased creatinine, BUN

HEMA:
Granulocytopenia, thrombocytopenia, irreversible neutropenia, anemia, eosinophilia

INTEG:
Rash
, alopecia,
pruritus
, urticaria, pain at site, phlebitis,
Stevens-Johnson syndrome

MISC:
Local and systemic infections,
sepsis

PHARMACOKINETICS

Metabolized to ganciclovir, which has a half-life of 3-4½ hr; excreted by kidneys (unchanged); crosses blood-brain barrier, CSF

INTERACTIONS

Increase:
Severe granulocytopenia: immunosuppressants, zidovudine, antineoplastics, radiation; do not use together

Increase:
toxicity—dapsone, pentamidine, flucytosine, vinCRIStine, vinBLAStine, adriamycin, DOXOrubicin, amphotericin B, trimethoprim-sulfamethoxazole combinations or other nucleoside analogs, cycloSPORINE

Increase:
effect of both drugs—mycophenolate

Increase:
seizures—imipenem-cilastatin

Increase:
effect of didanosine; monitor for adverse effects, toxicity

Decrease:
renal clearance of valGANciclovir—probenecid

Drug/Food

Increase:
absorption, high-fat meal

Drug/Lab Test

Increase:
creatinine

Decrease:
RBC/WBC, Hct/Hgb

NURSING CONSIDERATIONS
Assess:

• 
CMV retinitis by ophthalmoscopy before beginning treatment, q2wk; culture for CMV retinitis

 

Black Box Warning:

Leukopenia/neutropenia/thrombocytopenia: WBCs, platelets q2days during 2×/day dosing then q1wk; leukopenia with daily WBC count in patients with prior leukopenia with other nucleoside analogs or for whom leukopenia counts are <1000 cells/mm
3
at start of treatment

• 
Serum creatinine or CCr ≥q2wk

Evaluate:

• 
Therapeutic response: decreased symptoms of CMV

Teach patient/family:

• 
That product does not cure condition; that regular ophthalmologic and blood tests necessary

• 
That major toxicities may necessitate discontinuing product

• 
To use contraception during treatment; that infertility may occur; that men should use barrier contraception for 90 days after treatment

• 
To take with food

 
Blood dyscrasias: bruising, bleeding, petechiae; seizures, dizziness; to avoid hazardous activities

• 
To use sunscreen to prevent burns

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

valproate (Rx)

(val′proh-ate)

Depacon

valproic acid (Rx)

(val′proh-ik)

Depakene, Stavzor

divalproex sodium (Rx)

(dye-val′proh-ex)

Depakote, Depakote ER, Epival

Func. class.:
Anticonvulsant, vascular headache suppressant

Chem. class.:
Carboxylic acid derivative

ACTION:

Increases levels of γ-aminobutyric acid (GABA) in the brain, which decreases seizure activity

USES:

Simple (petit mal), complex (petit mal), absence, mixed, seizures; manic episodes associated with bipolar disorder, prophylaxis of migraine, adjunct for schizophrenia, tardive dyskinesia, aggression in children with ADHD, organic brain syndrome, mania, migraines; tonic-clonic (grand mal), myoclonic seizures

Unlabeled uses:
Rectal for seizures (valproic acid)

CONTRAINDICATIONS:

Hypersensitivity, urea cycle disorders

 

Black Box Warning:

Pregnancy (D), hepatic disease, pancreatitis

Precautions:
Breastfeeding, geriatric patients

 

Black Box Warning:

Children <2 yr

DOSAGE AND ROUTES
Calculator
Epilepsy

• Adult and child:
PO
10-15 mg/kg/day in 2-3 divided doses, may increase by 5-10 mg/kg/day weekly, max 60 mg/kg/day in 2-3 divided doses;
IV
≤20 mg/min over 1 hr

Status epilepticus refractory to diazepam IV (unlabeled)

• Adult:
RECT
400-600 mg PR as enema or wax-based suppository (not commercially available)

• Child:
RECT
20 mg/kg/dose

Mania (divalproex sodium)

• Adult:
PO
750 mg/day in divided doses, max 60 mg/kg/day or 3000 mg/day

Mania (valproic acid: Stavzor)

• Adult:
DEL REL CAP
750 mg/day in divided doses

Migraine (divalproex sodium)

• Adult:
PO
250 mg bid, may increase to 1000 mg/day if needed or 500 mg (Depakote ER) daily × 7 days, then 1000 mg/day

Available forms:
Valproate:
inj 100 mg/ml;
valproic acid:
caps 250 mg; oral solution 250 mg/5 ml; del rel cap (Stavzor) 125, 250, 500 mg;
divalproex:
gastro-resistant tabs 125, 250, 500 mg; ext rel tabs 250, 500 mg cap gastro-resistant; sprinkle cap 125 mg

Administer:
PO route

• 
Swallow tabs or caps whole; do not break, crush, or chew ext rel tabs

• 
Sprinkle cap contents on food

• 
Oral solution alone; do not dilute with carbonated beverage; do not give oral solution to patients with sodium restrictions

• 
Give with food or milk to decrease GI symptoms

SIDE EFFECTS

CNS:
Sedation, drowsiness
, dizziness, headache, incoordination, depression, hallucinations, behavioral changes, tremors, aggression, weakness,
coma, suicidal ideation, hypothermia

EENT:
Visual disturbances, taste perversion

GI:
Nausea, vomiting, constipation, diarrhea, dyspepsia
, anorexia, cramps,
hepatic failure, pancreatitis, toxic hepatitis,
stomatitis, weight gain

GU:
Enuresis, irregular menses

HEMA:
Thrombocytopenia, leukopenia, lymphocytosis,
increased PT, bruising, epistaxis

INTEG:
Rash
, alopecia, photosensitivity, dry skin

META:
Hyperammonemia

PHARMACOKINETICS

Metabolized by liver; excreted by kidneys, in breast milk; crosses placenta; half-life 6-16 hr; 90% protein binding

PO:
Peak 4 hr (regular rel); 4-17 hr (ext rel)

INTERACTIONS

Increase:
valproic acid toxicity level—erythromycin, felbamate, salicylates, NSAIDs, rifampin

Increase:
CNS depression—alcohol, opioids, barbiturates, antihistamines, MAOIs, sedative/hypnotics, tricyclics

Increase:
action of, possible toxicity phenytoin, carBAMazepine, ethosuximide, barbiturates, zidovudine, LORazepam, rufinamide, lamoTRIgine

Increase:
bleeding—warfarin

Decrease:
seizure threshold—tricyclics

Drug/Lab Test

False positive:
ketones, urine

Interference:
thyroid function tests

Increase:
LFTs, bleeding time, ammonia

NURSING CONSIDERATIONS
Assess:

• 
Seizure disorder:
location, aura, activity, duration; seizure precautions should be in place

 
Mental status: bipolar disorder: mood, activity, sleeping/eating, behavior; suicidal thoughts/behaviors

• 
Migraines:
frequency, intensity, alleviating factors

• 
Blood studies: Hct, Hgb, RBC, serum folate, PT/PTT, serum ammonia, platelets, vit D if patient receiving long-term therapy

 

Black Box Warning:

Hepatic studies: AST, ALT, bilirubin; hepatic failure has occurred

• 
Hyperammonemic encephalopathy:
can be fatal in those with urea cycle disorders (UCD); lethargy, confusion, coma, CV, respiratory changes; discontinue

• 
Blood levels: therapeutic level 50-100 mcg/ml, during seizures

 

Black Box Warning:

Pancreatitis;
may be fatal, report immediately nausea, vomiting, anorexia, abdominal pain

Evaluate:

• 
Therapeutic response: decreased seizures

Teach patient/family:

• 
That physical dependency may result from extended use

• 
To avoid driving, other activities that require alertness

• 
To drink plenty of fluids

• 
Not to discontinue medication quickly after long-term use because seizures may result

• 
To report visual disturbances, rash, diarrhea, abdominal pain, light-colored stools, jaundice, protracted vomiting, weakness to prescriber

• 
To use contraception while taking this product; pregnancy category (D)

• 
Overdose symptoms: heart block, coma

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