Product Details

CAFFEINE

A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes smooth muscle, stimulates cardiac muscle, stimulates diuresis, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide phosphodiesterases, antagonism of adenosine receptors, and modulation of intracellular calcium handling.

Indication

For management of fatigue, orthostatic hypotension, and for the short term treatment of apnea of prematurity in infants.

Associated Conditions

• Primary apnea of premature newborns
• Tiredness

Pharmacodynamics

Caffeine, a naturally occurring xanthine derivative like theobromine and the bronchodilator theophylline, is used as a CNS stimulant, mild diuretic, and respiratory stimulant (in neonates with apnea of prematurity). Often combined with analgesics or with ergot alkaloids, caffeine is used to treat migraine and other headache types. Over the counter, caffeine is available to treat drowsiness or mild water-weight gain.

Mechanism of action

Caffeine stimulates medullary, vagal, vasomotor, and respiratory centers, promoting bradycardia, vasoconstriction, and increased respiratory rate. This action was previously believed to be due primarily to increased intracellular cyclic 3′,5′-adenosine monophosphate (cyclic AMP) following inhibition of phosphodiesterase, the enzyme that degrades cyclic AMP. It is now thought that xanthines such as caffeine act as antagonists at adenosine-receptors within the plasma membrane of virtually every cell. As adenosine acts as an autocoid, inhibiting the release of neurotransmitters from presynaptic sites but augmenting the actions of norepinephrine or angiotensin, antagonism of adenosine receptors promotes neurotransmitter release. This explains the stimulatory effects of caffeine. Blockade of the adenosine A1 receptor in the heart leads to the accelerated, pronounced "pounding" of the heart upon caffeine intake.

Absorption

Readily absorbed after oral or parenteral administration. The peak plasma level for caffeine range from 6-10mg/L and the mean time to reach peak concentration ranged from 30 minutes to 2 hours.

Volume of distribution

• 0.8 to 0.9 L/kg [infants]
• 0.6 L/kg [adults]

Protein binding

Low (25 to 36%).

Metabolism

Hepatic cytochrome P450 1A2 (CYP 1A2) is involved in caffeine biotransformation. About 80% of a dose of caffeine is metabolized to paraxanthine (1,7-dimethylxanthine), 10% to theobromine (3,7-dimethylxanthine), and 4% to theophylline (1,3-dimethylxanthine).

• Caffeine
   
  Theobromine
• Caffeine
   
  Theophylline
  • Theophylline
     
    1-Methylxanthine
    • 1-Methylxanthine
       
      1-Methyluric acid
• Caffeine
   
  1,3,7-Trimethyluric acid
• Caffeine
   
  Paraxanthine
  • Paraxanthine
     
    1,7-Dimethyluric acid
  • Paraxanthine
     
    5-Acetylamino-6-formylamino-3-methyluracil
  • Paraxanthine
     
    1-Methylxanthine

Route of elimination

In young infants, the elimination of caffeine is much slower than that in adults due to immature hepatic and/or renal function.

Half life

3 to 7 hours in adults, 65 to 130 hours in neonates

Clearance

LD50=127 mg/kg (orally in mice)

SOURCE:DRUGBANK

Acetaminophen (N-Acetyl-p-Aminophenol; APAP)

A to Z Drug Facts

Acetaminophen (N-Acetyl-p-Aminophenol; APAP)

Action
Indications
Contraindications
Route/Dosage
Interactions
Lab Test Interferences
Adverse Reactions
PrecautionsPatient Care Considerations
Administration/Storage
Assessment/Interventions
Patient/Family Education

(ass-cet-ah-MEE-noe-fen)Acephen, Apacet, Arthritis Pain Formula Aspirin Free, Aspirin Free Anacin Maximum Strength, Bansesin, Children's Dynafed Jr., Children's Feverall, Children's Mapap, Children's Silapap, Children's Tylenol, Dapa, Datril Extra-Strength, Dolanex, Extra Strength Dynafed E.X., Feverall Sprinkle Caps, Genapap Extra Strength, Genebs, Halenol, Infants' Silapap, Junior Strength Panadol, Liquiprin, Mapap Extra Strength, Mapap Infant Drops, Mapap Regular Strength, Maranox Meda Cap, Myapap, Oraphen-PD, Panadol, Panex, Phenaphen, Redutemp, Ridenol, Snaplets-FR, Tapanol Extra Strength, Tempra, Tylenol, Tyenol Extended Relief, Tylenol Extra Strength Geltabs, Tylenol Infants' Drops, Tylenol Junior Strength, Uni-Ace,  Abenol, A.F. Anacin, Apo-Acetaminophen, Atasol, Children's Acetaminophen, Children's Chewable Acetaminophen, Extra Strength Acetaminophen, Pediatrix, PMS-Acetaminophen, Regular Strength Acetaminophen, Tempra, 222AF, TylenolClass: Analgesic/antipyretic

 Action Inhibits prostaglandins in CNS but lacks anti-inflammatory effects in periphery; reduces fever through direct action on hypothalamic heat-regulating center.

 Indications Relief of mild-to-moderate pain; treatment of fever. Unlabeled use(s): Pain and fever prophylaxis after vaccination.

 Contraindications Standard considerations.

 Route/Dosage

ORAL

ADULTS: PO 325 to 650 mg prn q 4 to 6 hr or 1 g 3 to 4 times/day. Do not exceed 4 g/day. CHILDREN: PO 10 to 15 mg/kg dose prn q 4 to 6 hr; do not exceed 5 doses/24 hr.

SUPPOSITORIES

ADULTS: PR 650 mg q 4 to 6 hr; do not exceed 6 suppositories/24 hr. CHILDREN: 3–6 YR: PR 120 mg q 4 to 6 hr; do not exceed 720 mg/24 hr. CHILDREN: 6–12 YR: PR 325 mg q 4 to 6 hr; do not exceed 2.6 g/24 hr.

 Interactions

Ethanol: Chronic excessive use may increase risk of hepatotoxicity. Hydantoins, sulfinpyrazone: May decrease therapeutic effect of APAP; concomitant long-term use may increase risk of hepatotoxicity.

 Lab Test Interferences With Chemstrip, bG Dextrostix, Visidex II home blood glucose measurement systems, drug may cause > 20% decrease in mean glucose.

 Adverse Reactions

HEMA: Hemolytic anemia; neutropenia; leukopenia; pancytopenia; thrombocytopenia. HEPA: Jaundice. OTHER: Hypoglycemia; allergic skin eruptions or fever.

 Precautions

Pregnancy: Category B. Lactation: Excreted in breast milk. Hepatic impairment: Chronic alcoholics should not exceed 2 g/day. Persistent pain or fever: May indicate serious illness. Physician should be consulted.

PATIENT CARE CONSIDERATIONS

 

 Administration/Storage

• Administer with water 30 min before or 2 hr after meals.
• Store tablets and capsules at room temperature in tightly closed container. Refrigerate suppositories. Refrigeration of elixir improves palatability.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Assess for pain and fever before and 1 to 2 hr after administration.
• Assess serum glucose and liver enzyme levels before long-term therapy.

OVERDOSAGE: SIGNS & SYMPTOMS Nausea, vomiting, abdominal pain, diarrhea, anorexia, malaise, diaphoresis, confusion, low BP, cardiac arrhythmias, jaundice, acute renal failure, liver failure

 Patient/Family Education

• Instruct family to consult physician for use in children < 3 yr and, not to continue taking drug > 5 days unless advised by physician.
• Instruct adult patients not to continue taking drug > 10 days for pain or 3 days for fever.
• Instruct patient/family to contact physician if pain or fever (> 103°F) persists > 3 days.
• Advise diabetic patients to use sugar-free form of drug.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts