Mosby's 2014 Nursing Drug Reference (261 page)

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

methylcellulose (
OTC
)

(meth-ill-sell′yoo-lose)

Citrucel, Equaline Fiber Therapy, Fiber Therapy, Leader Fiber Therapy, Walgreens Fiber Therapy

Func. class.:
Laxative, bulk forming

Chem. class.:
Hydrophilic semisynthetic cellulose derivative

Do not confuse:
Citrucel
/Citracal

ACTION:

Attracts water, expands in intestine to increase peristalsis; absorbs excess water in stool; decreases diarrhea

USES:

Chronic constipation

CONTRAINDICATIONS:

Hypersensitivity, GI obstruction, hepatitis

DOSAGE AND ROUTES
Calculator

• Adult:
PO
≤6 g/day in divided doses

• Child 6-12 yr:
PO
3 g/day in divided doses

Available forms:
Powder 105 mg/g, 196 mg/g; tab 500 mg

Administer:
PO route

• 
Alone for better absorption; do not take within 1 hr of other products

• 
In
AM
or
PM
(oral dose)

SIDE EFFECTS

GI:
Obstruction,
abdominal distention

PHARMACOKINETICS

PO:
Onset 12-24 hr, peak 1-3 days

INTERACTIONS

Decrease:
absorption—digoxin, nitrofurantoin, salicylates, tetracyclines, oral anticoagulants

Drug/Herb

Increase:
laxative action—flax senna

NURSING CONSIDERATIONS
Assess:

• 
Blood, urine electrolytes if used often

• 
I&O ratio to identify fluid loss

• 
Cause of constipation; lack of fluids, bulk, exercise, constipating products

• 
Cramping, rectal bleeding, nausea, vomiting; product should be discontinued

Evaluate:

• 
Therapeutic response: decrease in constipation

Teach patient/family:

• 
To mix powder in water, take with full glass of water

• 
To increase fluid intake

• 
That normal bowel movements do not always occur daily

• 
Not to use in presence of abdominal pain, nausea, vomiting

• 
To notify prescriber if constipation unrelieved or if symptoms of electrolyte imbalance occur: muscle cramps, pain, weakness, dizziness, excessive thirst

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

methyldopa/
methyldopate (Rx)

(meth-ill-doe′pa)

Func. class.:
Antihypertensive

Chem. class.:
Centrally acting α-adrenergic inhibitor

Do not confuse:
methyldopa
/
L
-dopa/levodopa

ACTION:

Stimulates central inhibitory α-adrenergic receptors or acts as false transmitter, resulting in reduction of arterial pressure

USES:

Hypertension, hypertensive crisis

CONTRAINDICATIONS:

Active hepatic disease, hypersensitivity

Precautions:
Pregnancy (B), geriatric patients, cardiac disease, autoimmune disease, depression, dialysis, hemolytic anemia, Parkinson’s disease, pheochromocytoma, sulfite hypersensitivity

DOSAGE AND ROUTES
Calculator

• Adult:
PO
250-500 mg bid or tid then adjusted q2days as needed, 0.5-2 g/day in 2-4 divided doses (maintenance), max 3 g/day;
IV
250-500 mg in 100 ml D
5
W q6hr, run over 30-60 min, max 1 g q6hr, switch to oral as soon as possible

• Geriatric:
PO
125 mg bid-tid, increase q2days as needed, max 3 g/day

• Child:
PO
10 mg/kg/day in 2-4 divided doses, max 65 mg/kg or 3 g/day, whichever is less;
IV
20-40 mg/kg/day in 4 divided doses, max 65 mg/kg or 3 g, whichever is less

Available forms:
Methyldopa:
tabs 250, 500 mg;
methyldopate:
inj 50 mg/ml

Administer:
PO route

• 
Increase in dose should be done in the evening to minimize drowsiness

Intermittent IV INF route

• 
After diluting with 100 ml D
5
W; run over 1/2-1 hr

Y-site compatibilities:
Alfentanil, amikacin, aminophylline, anidulafungin, ascorbic acid, atenolol, atracurium, atropine, aztreonam, benztropine, bivalirudin, bleomycin, bumetanide, buprenorphine, butorphanol, calcium chloride/gluconate, caspofungin, cefamandole, ceFAZolin, cefmetazole, cefonicid, cefotaxime, cefoTEtan, cefOXitin, cefTAZidime, ceftizoxime, cefTRIAXone, cefuroxime, cephalothin, chlorproMAZINE, cimetidine, clindamycin, cyanocobalamin, cycloSPORINE, DACTINomycin, DAPTOmycin, dexamethasone, digoxin, diltiazem, diphenhydrAMINE, DOCEtaxel, DOPamine, doxycycline, enalaprilat, ePHEDrine, EPINEPHrine, epoetin alfa, ertapenem, erythromycin, esmolol, etoposide, etoposide phosphate, famotidine, fenoldopam, fentaNYL, fluconazole, fludarabine, gatifloxacin, gemcitabine, gentamicin, glycopyrrolate, granisetron, heparin, hydrocortisone, HYDROmorphone, hydrOXYzine, IDArubicin, insulin (regular), irinotecan, isoproterenol, labetalol, lidocaine, linezolid, LORazepam, magnesium sulfate, mannitol, mechlorethamine, meperidine, metaraminol, methicillin, methoxamine, methylPREDNISolone, metoclopramide, metoprolol, metroNIDAZOLE, mezlocillin, miconazole, midazolam, milrinone, minocycline, mitoXANtrone, morphine, moxalactam, multiple vitamins, mycophenolate mofetil, nafcillin, nalbuphine, naloxone, netilmicin, nitroglycerin, nitroprusside, norepinephrine, octreotide, ondansetron, oxacillin, oxaliplatin, oxytocin, PACLitaxel, palonosetron, pamidronate, pancuronium, pantoprazole, papaverine, PEMEtrexed, penicillin G potassium/sodium, pentazocine, phentolamine, phenylephrine, phytonadione, piperacillin, polymyxin B, potassium chloride, procainamide, prochlorperazine, promethazine, propranolol, protamine, pyridoxine, quiNIDine, ranitidine, ritodrine,
sodium bicarbonate, succinylcholine, SUFentanil, tacrolimus, teniposide, theophylline, thiamine, thiotepa, ticarcillin, ticarcillin-clavulanate, tigecycline, tirofiban, tobramycin, tolazoline, trimetaphan, urokinase, vancomycin, vasopressin, vecuronium, verapamil, vinorelbine, voriconazole, zoledronic acid

SIDE EFFECTS

CNS:
Drowsiness, weakness, dizziness, sedation, headache
, depression, psychosis paresthesias, parkinsonism, Bell’s palsy, nightmares

CV:
Bradycardia,
myocarditis,
orthostatic hypotension, angina, edema, weight gain,
CHF,
paradoxic pressor response (IV)

EENT:
Nasal congestion

ENDO:
Breast enlargement, gynecomastia, amenorrhea

GI:
Nausea, vomiting, diarrhea, constipation,
hepatic dysfunction,
sore or “black” tongue,
pancreatitis,
colitis, flatulence

GU:
Impotence, failure to ejaculate

HEMA:
Leukopenia, thrombocytopenia, hemolytic anemia, granulocytopenia,
positive Coombs’ test

INTEG:
Rash,
toxic epidermal necrolysis,
lupuslike syndrome

PHARMACOKINETICS

PO:
Peak 2-4 hr, duration 12-24 hr

IV:
Peak 2 hr, duration 10-16 hr

Metabolized by liver, excreted in urine, half-life 2 hr

INTERACTIONS

• 
Lithium toxicity: lithium

 
Increase:
pressor effect—sympathomimetic amines, MAOIs; do not use concurrently with MAOIs

Increase:
hypotension, CNS toxicity—levodopa

Increase:
hypotension—diuretics, other antihypertensives

Increase:
psychosis—haloperidol

Increase:
CNS depression—alcohol, antihistamines, antidepressants, analgesics, sedative/hypnotics

Increase:
B/P—phenothiazines, β-blockers, amphetamines, NSAIDs, tricyclics, barbiturates

Increase:
hypoglycemia—TOLBUTamide

Decrease:
methyldopa absorption—iron

Drug/Lab Test

Increase:
creatinine, LFTs

Decrease:
platelets, WBC, Hgb/HcT

Interference:
urinary uric acid, serum creatinine, AST

False increase:
urinary catecholamines

NURSING CONSIDERATIONS
Assess:

• 
Blood studies: neutrophils, decreased platelets

• 
Hemolytic anemia:
Direct Coombs’ test before, after 6, 12 mo of therapy, a positive test may indicate hemolytic anemia; usually reverses within weeks to months after discontinuing treatment, monitor Hgb/HcT and RBC; do not start therapy in those with hemolytic anemia

• 
Baselines of renal, hepatic studies before therapy begins

• 
Hypertension:
B/P when beginning treatment, periodically thereafter; report significant changes

• 
Allergic reaction:
rash, fever, pruritus, urticaria; product should be discontinued if antihistamines fail to help

• 
CNS symptoms, especially in geriatric patients; depression, change in mental status

• 
CHF:
edema, dyspnea, wet crackles, B/P

• 
Renal symptoms: polyuria, oliguria, urinary frequency; I&O ratio, weight; report weight gain >5 lb

• 
Product tolerance:
may occur within 3 mo of starting treatment, a dosage change and other products may be needed

Evaluate:

• 
Therapeutic response: decrease in B/P with hypertension

Teach patient/family:

• 
To avoid hazardous activities

• 
Not to discontinue product abruptly because withdrawal symptoms may oc
cur: anxiety, increased B/P, headache, insomnia, increased pulse, tremors, nausea, sweating

• 
Not to use OTC (cough, cold, allergy) products unless directed by prescriber

• 
To rise slowly to sitting or standing position to minimize orthostatic hypotension

• 
To notify prescriber of mouth sores, sore throat, fever, swelling of hands or feet, irregular heartbeat, chest pain, signs of angioedema

• 
That excessive perspiration, dehydration, vomiting, diarrhea may lead to fall in B/P; to consult prescriber

• 
That dizziness, fainting, lightheadedness may occur during first few days of therapy

• 
That compliance is necessary; not to skip or stop product unless directed by prescriber

• 
That product may cause skin rash or impaired perspiration

TREATMENT OF OVERDOSE:

Gastric evacuation, sympathomimetics may be indicated; if severe, hemodialysis

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