caffeine
Cafcit, Caffedrine, Fastlene, NoDoz, Quick Pep, Vivarin

Available forms
Available by prescription only
Injection: 250 mg/ml, caffeine (121.25 mg/ml) with sodium benzoate (128.75 mg/ml)
Injection (as citrate): 20 mg/ml
Solution (as citrate): 20 mg/ml
Capsules: 200 mg
Tablets: 150 mg, 200 mg

Indications and dosages
 Apnea of prematurity in infants 28 to 33 weeks’ gestational age. Neonates: 20 mg/kg citrate I.V. infusion over 30 minutes as loading dose; 24 hours later, start 5 mg/kg I.V. (citrate) slow infusion over 10 minutes or P.O. q 24 hours.
 If giving caffeine base, give 10 mg/kg I.V. as loading dose; then 2.5 mg/kg I.V. Adjust dosage according to patient tolerance and plasma caffeine levels.
 Fatigue, drowsiness. Adults and children older than age 12: 100 to 200 mg P.O. q 3 to 4 hours, p.r.n.
 Respiratory depression. Adults: 500 mg caffeine and sodium benzoate I.M. Maximum dose is 1 g. Don’t exceed 2.5 g in 24 hours.

Pharmacodynamics
CNS stimulant action: A xanthine derivative; increases levels of cAMP by inhibiting phosphodiesterase. Caffeine stimulates all levels of the CNS. It hastens and clarifies thinking and improves arousal and psychomotor coordination.
Respiratory stimulant action: In respiratory depression and neonatal apnea, larger doses of caffeine increase respiratory rate. Caffeine increases contractile force and decreases fatigue of skeletal muscle.

Pharmacokinetics
Absorption: Well absorbed from GI tract; absorption after I.M. injection may be slower.
Distribution: Distributed rapidly throughout body; crosses blood-brain barrier and placental barrier. About 17% protein-bound.
Metabolism: Metabolized by the liver; in neonates, liver metabolism is much less evident and half-life may approach 80 hours. Plasma half-life in adults is 3 to 4 hours.
Excretion: Excreted in urine.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug. Use cautiously in patients with history of peptic ulcer, symptomatic arrhythmias, or palpitations, and after an acute MI.

Interactions
Drug-drug. Adenosine, dipyridamole: Impairs vasoactive effects of these drugs and may affect the diagnostic sensitivity of tests using these drugs. Avoid use together.
Beta blockers: Enhances inotropic effects of these drugs. Use together cautiously.
Beta agonists (albuterol, metaproterenol, terbutaline): Increases cardiac effects and tremors. Monitor patient closely.
Calcium, iron: Impairs mineral absorption. Discourage use together.
Fluoroquinolones such as cimetidine, ciprofloxacin, disulfiram, hormonal contraceptives: Inhibits caffeine metabolism and increases effects. Use together cautiously.
Lithium: Enhances excretion of lithium. Discourage use together. Monitor patient closely.
MAO inhibitors: May cause tachycardia, cardiac arrhythmias, and severe hypertension, depending on caffeine dose. Avoid use together.
Xanthine derivatives (theophylline): May increase stimulant-induced adverse reactions, such as tremor, tachycardia, insomnia, and nervousness. Use together cautiously.
Drug-herb. Ephedra: Increases CNS effects. Discourage use together.
Drug-lifestyle. Smoking: May enhance elimination of caffeine. Discourage smoking.

Adverse reactions
CNS: insomnia, restlessness, nervousness, headache, excitement, agitation, muscle tremor, twitching.
CV: tachycardia, palpitations, extrasystoles.
EENT: tinnitus.
GI: nausea, vomiting, diarrhea, stomach pain.
GU: diuresis.
Other: abrupt withdrawal symptoms (headache, irritability).

Effects on lab test results
• May increase serum glucose levels.

Overdose and treatment
Signs and symptoms of overdose in adults may include insomnia, dyspnea, altered states of consciousness, muscle twitching, seizure, diuresis, arrhythmias, and fever. In infants, symptoms of overdose may include alternating hypotonicity and hypertonicity, opisthotonoid posture, tremors, bradycardia, hypotension, and severe acidosis.
 Treat overdose symptomatically and supportively; lavage and charcoal may help. Carefully monitor vital signs, ECG, and fluid and electrolyte balance. Seizures may be treated with diazepam or phenobarbital; diazepam may exacerbate respiratory depression.

Special considerations
• Restrict caffeine-containing beverages in patients with arrhythmic symptoms and in those taking aminophylline or theophylline.
• Caffeine content in beverages (mg/cup): cola drinks, 24 to 64; brewed tea, 20 to 110; instant coffee, 30 to 120; brewed coffee, 40 to 180; decaffeinated coffee, 3 to 5.
• Many OTC pain relievers contain caffeine, but evidence concerning its analgesic effects is conflicting. Caffeine (30%) may be used in a hydrophilic base or hydrocortisone cream to treat atopic dermatitis.
• Caffeine may cause false-positive urate levels measured by the Bittner method. It also may cause false-positive test results for pheochromocytoma or neuroblastoma by increasing certain urinary catecholamines.
Breast-feeding patients
• Caffeine appears in breast milk. An alternative to breast-feeding is recommended during therapy with caffeine.
Pediatric patients
• For control of neonatal apnea, maintain plasma caffeine level at 5 to 20 mcg/ml.
• Adverse CNS effects are usually more severe in children.
• In neonates, avoid using caffeine products containing sodium benzoate; they may cause kernicterus.
Geriatric patients
• Elderly patients are more sensitive to caffeine and should take lower doses.

Patient education
• Advise patient to avoid excessive caffeine consumption, and therefore CNS stimulation, by learning caffeine content of beverages and foods.
• Warn patient not to exceed recommended dosage, not to substitute caffeine for needed sleep, and to stop drug if dizziness or tachycardia occurs.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use