OB-GYN 101
Pharmacy

Category:

• Respiratory

Description:

• Bronchodilator, antiasthmatic, COPD agent

Indications:

• Bronchial asthma

• Reversible bronchospasm of chronic bronchitis and emphysema

• Apnea and bradycardia of prematurity (non FDA approved)

Contraindications:

• Tachydysrhythmias; as sole treatment of status asthmaticus

• Active peptic ulcer disease, seizure disorders

Precautions:

• Pregnancy category C; no reports of malformations; compatible with breast feeding with precaution that rapidly absorbed preparations may cause irritability in the infant

• Elderly, CHF, cor pulmonale

• Hepatic disease, diabetes mellitus

• Hyperthyroidism, hypertension, active alcoholism, children, neonates

Adverse Reactions (Side Effects):

• CNS: anxiety, dizziness, headache, insomnia, lightheadedness, muscle twitching, restlessness, seizures

• CV: dysrhythmias, fluid retention with tachycardia, hypotension, palpitations, pounding heartbeat, sinus tachycardia

• GI: anorexia, bitter taste, diarrhea, dyspepsia, gastroesophageal reflux, nausea, vomiting

• GU: urinary frequency

• RESP: increased rate

• SKIN: flushing, urticaria

Administered orally, intravenously: Dose based on body weight. When converting to sustained release products, total daily dose remains the same but is divided every 8-24 hours depending on product and dose (doses >1200mg daily should be divided every 8 hours, doses <1200mg daily can be given every 12 hours

• Adult:   

  • Acute symptoms: PO 5 mg/kg load, maintenance 3 mg/kg every 8 hours (non-smokers), 3 mg/kg every 6 hours (smokers), 2 mg/kg every 8 hours (older patients), 1-2 mg/kg every 12 hours (CHF); IV 5 mg/kg load over 20 minutes, maintenance 0.2 mg/kg/hour (CHF, elderly), 0.43 mg/kg/hour (non-smokers), 0.7 mg/kg/hour (young adult smokers), measure serum level for patients currently receiving theophylline, approximately 0.5 mg/kg theophylline increases serum level 1 mcg/ml

  • Slow titration: PO initial dose 16 mg/kg/day or 400mg daily, whichever is less, doses divided every 6-8 hours

• PO dosage adjustment after serum theophylline measurement:

  • Serum level 5-10 mcg/ml, maintain dose by 25%, recheck level in 3 days

  • Serum level 10-20 mcg/ml, maintain dosage if tolerated, recheck level every 6-12 months

  • Serum level 20-25 mcg/ml, decrease dose by 10%, recheck level in 3 days

  • Serum level 25-30 mcg/ml, skip next dose, decrease dose by 25%, recheck level in 3 days

  • Serum level > 30 mcg/ml, skip next 2 doses, decrease dose by 50%, recheck level in 3 days

• Child:   

  • 9-16 years: PO 5 mg/kg load, maintenance 3 mg/kg every 6 hours; IV 5 mg/kg load over 20 minutes, maintenance 0.7 mg/kg/hour

  • 1-9 years: PO 5 mg/kg load, maintenance 4 mg/kg every 6 hours; IV 5 mg/kg load over 20 minutes, maintenance 0.8 mg/kg/hour

  • Infants: PO [(0.2 X age in weeks) +5] X kg = 24 hour dose in mg; divide into every 8 hour dosing (6week to 6 months), every 6 hour dosing (6-12 months); IV 5 mg/kg load over 20 minutes, maintenance dose in mg/kg/hour [(0.0008 X age in weeks) + 0.21]

Drug interactions:

• Enoxacin, fluoxamine, mexiletine, propranolol, troleandomycin: increased theophylline levels

• Allopurinol, amiodarone,m cimetadine, ciprofloxacin, disulfiram, erythromycin, interferon alpha, isoniazid, metoprolol, norfloxacin, pentoxyfylline, propafenone, radioactive iodine, tacrine, thiabendazole, ticlopidine, verapamil: increased theophylline levels

• Smoking: increased theophylline requirements

• Aminoglutethamide, barbiturates, carbamazepine, phenytoin, rifampin, ritonavir, thyroid hormone: reduced theophylline levels; decreased serum phenytoin levels