Mosby's 2014 Nursing Drug Reference (330 page)

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

primidone (Rx)

(pri′mi-done)

Mysoline, Sertan

Func. class.:
Anticonvulsant

Chem. class.:
Barbiturate derivative

ACTION:

Raises seizure threshold by conversion of product to PHENobarbital, decreases neuron firing

USES:

Generalized tonic-clonic (grand mal), complex seizures

Unlabeled uses:
Benign familial tremor (essential tremor)

CONTRAINDICATIONS:

Pregnancy (D), breastfeeding, hypersensitivity, porphyria, hepatic encephalopathy

Precautions:
Hyperactive children, COPD, renal/hepatic disease, suicidal ideation/behavior

DOSAGE AND ROUTES
Calculator

• Adult and child
>
8 yr:
PO
125-250 mg at bedtime, increase by 125-250 mg/day q3-7days, usual dose 750-1500 mg/day in 3-4 divided doses, max 2 g/day in divided doses

• Child
<
8 yr:
PO
50-125 mg at bedtime, increase by 50-125 mg/day q3-7days, usual dose 10-25 mg/kg/day in 3-4 divided doses

• Neonate:
PO
12-20 mg/kg/day in 2-4 divided doses, start at lower dose and titrate

Benign familial tremor/essential tremor (unlabeled)

• Adult:
PO
50-62.5 mg, increase as tolerated up to 750 mg/day in 3 divided doses

Renal dose

• Adult:
PO
CCr 10-50 ml/min, increase interval between doses to 8-12 hr; CCr <10 ml/min, increase interval to 12-24 hr

Available forms:
Tabs 50, 250 mg; susp 250 mg/5 ml
; chew tabs 125 mg

Administer:
PO route

• 
After shaking liquid susp well

• 
With food for GI upset

• 
Tablets crushed and mixed with food or fluid for swallowing difficulties

• 
Avoid use with CNS depressants

SIDE EFFECTS

CNS:
Stimulation, drowsiness
, irritability, psychosis, ataxia, vertigo, fatigue, emotional disturbances, mood changes, paranoia,
suicidal ideation

EENT:
Diplopia, nystagmus, edema of eyelids

GI:
Nausea, vomiting, anorexia
,
hepatitis

GU:
Impotence

HEMA:
Thrombocytopenia, leukopenia, neutropenia, eosinophilia, megaloblastic anemia,
decreased serum folate level, lymphadenopathy

INTEG:
Rash
, edema, alopecia, lupuslike syndrome

PHARMACOKINETICS

PO:
Peak 4 hr; metabolized in liver; excreted by kidneys, in breast milk; half-life 10-12 hr (primidone)

INTERACTIONS

• 
Primidone levels decreased by acetaZOLAMIDE, succinimides

• 
May decrease effect of oral contraceptives, acebutolol, metoprolol, propranolol, tricyclics, phenothiazines, lamoTRIgine, estrogens, non-oral combination contraceptives, progestins

Increase:
primidone levels—alcohol, heparin, CNS depressants, isoniazid, nicotinamide, MAOIs

Increase:
toxicity—CYP3A4 inhibitors (aprepitant, antiretroviral protease inhibitors, delavirdine, fluconazole, imatinib, voriconazole)

Decrease:
primidone effect—CYP3A4 inducers (barbiturates, carBAMazepine, efavirenz, phenytoins, nevirapine)

Drug/Herb

• 
Avoid use with kava, St. John’s wort, valerian

Increase:
effect—ginkgo

Decrease:
effect—ginseng, santonica

NURSING CONSIDERATIONS
Assess:

• 
Seizures:
location, duration, type; folic acid deficiency; fatigue, weakness, neuropathy, depression

• 
Product level: therapeutic level 5-15 mcg/ml; CBC, LFTs should be obtained q6mo

 
Mental status: mood, sensorium, affect, memory (long, short), suicidal thoughts/behaviors

• 
Respiratory depression, wheezing

• 
Blood dyscrasias: fever, sore throat, bruising, rash, jaundice

Evaluate:

• 
Therapeutic response: decreased seizures

Teach patient/family:

• 
Not to withdraw product quickly because withdrawal symptoms may occur

• 
To avoid hazardous activities until stabilized on product because drowsiness, dizziness may occur

• 
To carry emergency ID with condition, medication listed

• 
To recognize signs of blood dyscrasias; about when to notify prescriber

• 
To avoid alcohol

• 
Contraception:
Use additional contraceptive during and for 1 mo after therapy, contraceptive may be reduced

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

probenecid (Rx)

(proe-ben′e-sid)

Func. class.:
Uricosuric, antigout agent

Chem. class.:
Sulfonamide derivative

ACTION:

Inhibits tubular reabsorption of urates, with increased excretion of uric acids

USES:

Hyperuricemia in gout, gouty arthritis, adjunct to penicillin treatment

CONTRAINDICATIONS:

Hypersensitivity, severe renal/hepatic disease, CCr <50 mg/min, history of uric acid calculus

Precautions:
Pregnancy (C), children <2 yr, sulfonamide hypersensitivity, pepticular

DOSAGE AND ROUTES
Calculator
Adjunct to penicillin

• Adult/adolescent >15 yr, >50 kg (110 lb):
PO
500 mg qid

Gout/gouty arthritis

• Adult:
PO 250 mg bid for 1 wk, then 500 mg bid, max 2 g/day; maintenance 500 mg/day × 6 mo

Adjunct in penicillin treatment

• Adult and adolescent
>
50 kg:
PO
500 mg qid

• Child
<
50 kg:
PO
25 mg/kg, then 40 mg/kg in divided doses qid

Renal dose

• 
Avoid use if CCr <50 ml/min

Available forms:
Tabs 500 mg

Administer:

• 
After meals or with milk if GI symptoms occur

• 
Increase fluid intake to 2-3 L/day to prevent urinary calculi

SIDE EFFECTS

CNS:
Drowsiness, headache, flushing

CV:
Bradycardia

GI:
Gastric irritation, nausea, vomiting, anorexia
,
hepatic necrosis

GU:
Glycosuria, thirst, frequency,
nephrotic syndrome

INTEG:
Rash, dermatitis, pruritus, fever

META:
Acidosis, hypokalemia, hyperchloremia
, hyperglycemia

RESP:
Apnea,
irregular respirations

PHARMACOKINETICS

Peak 2-4 hr, duration 8 hr, half-life 5-8 hr; metabolized by liver; excreted in urine

INTERACTIONS

Increase:
effect of acyclovir, barbiturates, allopurinol, benzodiazepines, dyphylline, zidovudine, cephalosporins, penicillins, sulfonamides

Increase:
toxicity—sulfa products, dapsone, clofibrate, indomethacin, rifampin, naproxen, methotrexate

Decrease:
action of probenecid—salicylates

Drug/Lab Test

Increase:
theophylline levels

NURSING CONSIDERATIONS
Assess:

• 
Uric acid levels (3-7 mg/dl); mobility, joint pain, swelling

• 
Respiratory rate, rhythm, depth; notify prescriber of abnormalities

• 
Electrolytes; CO
2
before, during treatment

• 
Urine pH, output, glucose during beginning treatment

 
For CNS symptoms: confusion, twitching, hyperreflexia, stimulation, headache; may indicate overdose

Evaluate:

• 
Therapeutic response: absence of pain, stiffness in joints

Teach patient/family:

• 
To avoid OTC preparations (aspirin) unless directed by prescriber; increase water intake, avoid alcohol, caffeine

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