Mosby's 2014 Nursing Drug Reference (35 page)

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

amoxicillin (Rx)

(a-mox-i-sill′in)

Moxatag

Func. class.:
Antiinfective, antiulcer

Chem. class.:
Aminopenicillin

Do not confuse:
amoxicillin
/amoxapine/Amoxil
Trimox
/Diamox/Tylox
Wymox
/Tylox

ACTION:

Interferes with cell wall replication of susceptible organisms; the cell wall, rendered osmotically unstable, swells and bursts from osmotic pressure; bactericidal: lysis mediated by bacterial cell wall autolysins

USES:

Treatment of skin, respiratory, GI, GU infections, otitis media, gonorrhea; for gram-positive cocci
(Staphylococcus aureus, Streptococcus pyogenes, Streptococcus faecalis, Streptococcus pneumoniae)
, gram-negative cocci
(Neisseria gonorrhoeae, Neisseria meningitidis)
, gram-positive bacilli
(Corynebacterium diphtheriae, Listeria monocytogenes)
, gram-negative bacilli
(Haemophilus influenzae, Escherichia coli, Proteus mirabilis, Salmonella);
β-lactase–negative organisms; prophylaxis of bacterial endocarditis; in combination with other products for treatment of
Helicobacter pylori

Unlabeled uses:
Lyme disease, anthrax treatment and prophylaxis, cervicitis,
Chlamydia trachomatis
, dental abscess/infection, dyspepsia, gastric ulcer, non-gonococcal urethritis, periodontitis, typhoid fever

CONTRAINDICATIONS:

Hypersensitivity to penicillins

Precautions:
Pregnancy (B), breastfeeding, neonates, hypersensitivity to cephalosporins, severe renal disease, acute lymphocytic leukemia, mononucleosis, phenylketonuria

DOSAGE AND ROUTES
Calculator
Systemic infections (severe)

• Adult: PO
750 mg-1.75 g/day in divided doses q8hr or q12hr

• Child:
PO
20-50 mg/kg/day in divided doses q8hr or q12hr

S. pyogenes
infection (pharyngitis/tonsillitis)

• Adult/child
>
12 yr:
PO EXT REL
775 mg every day with meal × 10 days

Gonorrhea

• Adult: PO
3 g given with 1 g probenecid as a single dose followed by tetracycline or erythromycin therapy

C. trachomatis

• Adult: PO
500 mg/tid × 1 wk

Bacterial endocarditis prophylaxis (unlabeled)

• Adult: PO
2 g 1 hr before procedure

• Child:
PO
50 mg/kg 1 hr before procedure; max 2 g

Renal disease

• Adult: PO
CCr 10-30 ml/min 250-500 mg q12hr; CCr <10 ml/min 250-500 mg q24hr; do not use 775, 875 mg strength if CCr <30 ml/min

Lyme disease (unlabeled)

• Adult: PO
250-500 mg tid × 10-30 days

• Child:
PO
20-50 mg/kg/day in divided doses q8hr × 10-30 days

Duodenal/gastric ulcer/dyspepsia from
H. pylori
infection (unlabeled)

• Adult: PO
1000 mg bid with lansoprazole or clarithromycin/omeprazole

Anthrax treatment/prophylaxis (unlabeled)

• Adult and child
>
20 kg:
PO
500 mg q8hr × 10-14 days (prophylaxis), 60 days (treatment)

• Child
<
20 kg:
PO
80 mg/kg divided in 3 doses q8hr × 60 days (treatment)

Available forms:
Caps 250, 500 mg; chew tabs 125, 200, 250, 400 mg; tabs 250, 500, 875 mg; ext rel tab (Moxatag) 775 mg; susp 125, 200, 250, 400 mg/5 ml

Administer:
PO route

• 
Susp:
shake well before each dose; may be used alone, mixed in drinks; use immediately; discard unused portion after 14 days, store in refrigerator

• 
Give around the clock; caps may be emptied, mixed with liquids if needed without regard to food

• 
Ext rel:
do not crush, chew, break, take with food

SIDE EFFECTS

CNS:
Headache,
seizures,
agitation, confusion, dizziness, insomnia

GI:
Nausea, vomiting, diarrhea
, increased AST, ALT, abdominal pain, glossitis, colitis,
pseudomembranous colitis,
jaundice, cholestasis

HEMA:
Anemia, increased bleeding time,
bone marrow depression, granulocytopenia, hemolytic anemia

INTEG:
Urticaria, rash

SYST:
Anaphylaxis, respiratory distress, serum sickness, Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis

PHARMACOKINETICS

PO:
Peak 2 hr, duration 6-8 hr, half-life 1-1⅓ hr, metabolized in liver, excreted in urine, crosses placenta, enters breast milk

INTERACTIONS

Increase:
rash—allopurinol

Increase:
amoxicillin level—probenecid

Increase:
anticoagulant action—warfarin

Increase:
methotrexate levels—methotrexate

Decrease:
effectiveness of oral contraceptives

Drug/Lab Test

Increase:
AST/ALT, alk phos, LDH

False positive:
direct Coombs’s test

NURSING CONSIDERATIONS
Assess:

• 
Report hematuria, oliguria, penicillin products, in high doses are nephrotoxic

• 
Hepatic studies: AST, ALT

• 
Blood studies: WBC, RBC, Hgb, Hct, bleeding time

• 
Renal studies: urinalysis, protein, blood, BUN, creatinine

• 
C&S before product therapy; product may be given as soon as culture is taken

 
Pseudomembranous colitis:
bowel pattern before, during treatment; diarrhea, cramping, blood in stools; report to prescriber

• 
Skin eruptions after administration of penicillin to 1 wk after discontinuing product, rash is more common if allopurinol is taken concurrently

 
Anaphylaxis:
rash, itching, dyspnea, facial/laryngeal edema

Perform/provide:

• 
Scratch test to assess allergy after securing order from prescriber; usually done when penicillin is only product of choice

Evaluate:

• 
Therapeutic response: absence of infection; prevention of endocarditis, resolution of ulcer symptoms

Teach patient/family:

• 
That caps may be opened, contents taken with fluids; that chewable form is available; to take as prescribed, not to double dose

• 
All aspects of product therapy: to complete entire course of medication to ensure organism death (10-14 days); that culture may be taken after completed course of medication

 
To report sore throat, fever, fatigue, diarrhea
(superinfection or agranulocytopenia),
blood in stool, abdominal pain
(pseudomembranous colitis),
decreased urinary output

• 
That product must be taken in equal intervals around the clock to maintain blood levels; to take without regard to food

• 
To wear or carry emergency ID if allergic to penicillins

TREATMENT OF ANAPHYLAXIS:

Withdraw product, maintain airway; administer EPINEPHrine, aminophylline, O
2
, IV corticosteroids

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

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