Mosby's 2014 Nursing Drug Reference (386 page)

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tenofovir (Rx)

(ten-oh-foh′veer)

Viread

Func. class.:
Antiretroviral

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

ACTION:

Inhibits replication of HIV virus by competing with the natural substrate and then incorporating into cellular DNA by viral reverse transcriptase, thereby terminating cellular DNA chain

USES:

HIV-1 infection with at least 2 other antiretrovirals, hepatitis B

CONTRAINDICATIONS:

Hypersensitivity

 

Black Box Warning:

Lactic acidosis

Precautions:
Pregnancy (B), breastfeeding, children, geriatric patients, renal disease, CCr <60 ml/min, osteoporosis, immune reconstitution syndrome

 

Black Box Warning:

Hepatic disease, hepatitis

DOSAGE AND ROUTES
Calculator

• Adult:
PO
300 mg/day with meal; if used with didanosine, give tenofovir 2 hr before or 1 hr after didanosine

• Child ≥2 yr:
PO
8 mg/kg daily approximate; ≥35 kg 300 mg daily; 28-34 kg 250 mg daily; 22-27 kg 200 mg daily; 17-21 kg 150 mg daily

Renal dose

• Adult:
PO
CCr 30-49 ml/min, 300 mg q48hr; CCr 10-29 ml/min, 300 mg q72-96hr; CCr <10 ml/min, not recommended

Available forms:
Tabs 150, 200, 250, 300 mg; oral powder 40 mg/scoop

Administer:

• 
Without regard to food

• 
2 hr before or 1 hr after didanosine (if used)

• 
Oral powder:
use scoop provided, mix powder into 2-4 oz (1/4-1/2 cup) of applesauce, yogurt, do not mix with liquid, product is bitter, use immediately after mixing, clean scoop

SIDE EFFECTS

CNS:
Headache, asthenia

GI:
Nausea, vomiting, diarrhea
, anorexia,
flatulence, abdominal pain
,
pancreatitis

GU:
Renal failure, renal tubular acidosis/necrosis, Fanconi syndrome

HEMA:
Neutropenia, osteopenia

INTEG:
Rash
,
angioedema

META:
Lactic acidosis,
hypokalemia, hypophosphatemia

MS:
Myopathy,
rhabdomyolysis

SYST:
Lipodystrophy

PHARMACOKINETICS

Rapidly absorbed, distributed to extravascular space, excreted unchanged in urine 70%-80%, terminal half-life 17 hr, peak 1-2 hr

INTERACTIONS

Increase:
tenofovir level—cidofovir, acyclovir, valacyclovir, ganciclovir, valganciclovir

Increase:
level of didanosine when given with tenofovir

Increase:
tenofovir level—any product that decreases renal function

NURSING CONSIDERATIONS
Assess:

• 
Viral load, CD4+ T-cell count, plasma HIV RNA, serum creatinine/BUN/phosphate

• 
Resistance testing at start of therapy and at treatment failure

• 
Hepatic studies: AST, ALT, bilirubin; amylase, lipase, triglycerides periodically during treatment

• 
Bone, renal toxicity: if bone abnormalities are suspected, obtain tests; serum phosphorus, creatinine

• 
Lactic acidosis, severe hepatomegaly with steatosis, Fanconi syndrome:
obtain baseline liver function tests; if elevated, discontinue treatment; discontinue even if liver function tests normal but lactic acidosis, hepatomegaly present, may be fatal

Perform/provide:

• 
Storage at 25° C (77° F)

Evaluate:

• 
Therapeutic response: decrease in signs, symptoms of HIV

Teach patient/family:

• 
To take without regard to food

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

• 
Not to breastfeed while taking this product

• 
That product must be taken daily even if patient feels better

• 
That follow-up visits must be continued because serious toxicity may occur; that blood counts must be done q2wk

• 
That product will control symptoms but is not a cure for HIV; that patient is still infectious, may pass HIV virus on to others

• 
That other products may be necessary to prevent other infections

• 
That changes in body fat distribution may occur

• 
To notify prescriber of symptoms of lactic acidosis

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

terazosin (Rx)

(ter-ay′zoe-sin)

Func. class.:
Antihypertensive

Chem. class.:
α-Adrenergic blocker

ACTION:

Decreases total vascular resistance, which is responsible for a decrease in B/P; this occurs by the blockade of α
1
-adrenoreceptors

USES:

Hypertension, as a single agent or in combination with diuretics or β-blockers; BPH

CONTRAINDICATIONS:

Hypersensitivity

Precautions:
Pregnancy (C), breastfeeding, children, prostate cancer, renal disease, syncope

DOSAGE AND ROUTES
Calculator
Hypertension

• Adult:
PO
1 mg at bedtime, may increase dose slowly to desired response; max 20 mg/day

Benign prostatic hyperplasia

• Adult:
PO
1 mg at bedtime, gradually increase up to 5-10 mg; max 20 mg

Available forms:
Caps 1, 2, 5, 10 mg

Administer:

• 
Give dose at bedtime; patient should not operate machinery because fainting may occur

• 
If treatment is interrupted for several days, restart with initial dose

• 
Without regard to food; feeding tube: place cap in 60 ml of warm tap water, stir until liquid spills from ruptured shell (5 min), stir until cap dissolves, draw solution into oral syringe, give through feeding tube, flush with water

SIDE EFFECTS

CNS:
Dizziness, headache, drowsiness
, anxiety, depression, vertigo, weakness, fatigue

CV:
Palpitations, orthostatic hypotension, tachycardia, edema, rebound hypertension

EENT:
Blurred vision, epistaxis, tinnitus, dry mouth, red sclera, nasal congestion, sinusitis

GI:
Nausea
, vomiting, diarrhea, constipation, abdominal pain

GU:
Urinary frequency, incontinence, impotence, priapism

RESP:
Dyspnea, cough, pharyngitis

PHARMACOKINETICS

Half-life 9-12 hr; protein binding 90%-94%; metabolized in liver; excreted in urine, feces, peak 2-3 hr, onset 15 min, duration 24 hr

INTERACTIONS

Increase:
hypotensive effects—β-blockers, nitroglycerin, verapamil, other antihypertensives, alcohol

Decrease:
hypotensive effects—estrogens, NSAIDs, sympathomimetics, salicylates

Drug/Herb

Increase:
antihypertensive effect—hawthorn

Decrease:
antihypertensive effect—ephedra

Drug/Lab Test

Decrease:
Hgb, WBC, platelets, albumin

NURSING CONSIDERATIONS
Assess:

• 
BPH:
urinary patterns (hesitancy, frequency, change in stream, dribbling, dysuria, urgency)

• 
Hypertension:
crackles, dyspnea, orthopnea q30min; orthostatic B/P, pulse, jugular venous distention q4hr; weight daily, I&O

• 
BUN, uric acid if patient receiving long-term therapy

Perform/provide:

• 
Cool storage in tight container

Evaluate:

• 
Therapeutic response: decreased B/P, edema in feet, legs; decreased symptoms of BPH

Teach patient/family:

• 
That fainting occasionally occurs after 1st dose; not to drive or operate machinery for 4 hr after 1st dose or after an increase in dose; to take 1st dose at bedtime

• 
To rise slowly from sitting or lying position

• 
Not to discontinue abruptly

• 
Hypertension:
to continue with regimen including diet, exercise

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

terbinafine oral (Rx)

(ter-bin′a-feen)

Lamisil

Func. class.:
Antifungal

Chem. class.:
Synthetic allylamine derivative

Do not confuse:
terbinafine
/terbutaline
LamISIL
/LaMICtal

ACTION:

Interferes with cell-membrane permeability of fungi such as
Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton tonsurans, Epidermophyton floccosum, Microsporum canis, Microsporum audouinii, Microsporum gypseum, Candida;
broad-spectrum antifungal

USES:

(Oral) onychomycosis of toenail or fingernail due to dermatophytes, tinea capititis/corporis/cruris/pedis/versicolor

Unlabeled uses:
Cutaneous candidiasis, tinea versicolor

CONTRAINDICATIONS:

Hypersensitivity/olfactory, chronic/active hepatic disease, renal disease GFR ≤50 ml/min

Precautions:
Pregnancy (B), breastfeeding, children, renal disease

DOSAGE AND ROUTES
Calculator

• Adult:
PO
250 mg/day × 6 wk (fingernail); × 12 wk (toenail)

Available forms:
Tabs 250 mg; oral granules 125, 187.5 mg

Administer:

• 
PO:
without regard to food

• 
Granules:
take with food, sprinkle packet contents on pudding or nonacidic soft food, swallow without chewing, do not use fruit-based foods

SIDE EFFECTS

CNS:
Depression

EENT:
Tinnitus, hearing impairment

GI:
Diarrhea, dyspepsia, vertigo, abdominal pain, nausea, hepatitis

HEMA:
Neutropenia

INTEG:
Rash, pruritus, urticaria,
Stevens-Johnson syndrome,
photosensitivity

MISC:
Headache, hepatic enzyme changes, taste, visual/olfactory disturbance

PHARMACOKINETICS

Peak 1-2 hr, >99% protein binding, half-life 36 hr

INTERACTIONS

Increase:
levels of dextromethorphan

Increase:
terbinafine clearance—rifampin

Increase:
clearance of cycloSPORINE

Decrease:
terbinafine clearance—cimetidine

Decrease:
metabolism of—CYP2D6 (antidysrthymics IC, III, amoxapine, atomoxetine, cloZAPine

Drug/Herb

• 
Side effects: cola nut, guarana, yerba maté, tea (black, green), coffee

Drug/Lab Test

Increase:
LFTs

NURSING CONSIDERATIONS
Assess:

• 
Hepatic studies (ALT, AST) prior to beginning treatment; do not use in presence of hepatic disease

• 
CBC in treatment >6 wk

• 
Continuing infection: increased size, number of lesions

Perform/provide:

• 
Storage at <25° C (77° F), protect from light

Evaluate:

• 
Therapeutic response: decrease in size, number of lesions

Teach patient/family:

• 
That treatment may take 10 wk (toenail), 4 wk (fingernail)

• 
To notify prescriber of nausea, vomiting, fatigue, jaundice, dark urine, clay-colored stool, RUQ pain; may indicate hepatic dysfunction

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