Paracetamol: Uses, Side Effects, Mechanism, Dosage

Acetaminophen belong to a class of drug Called analgesic(pain reliever) and antipyretics(fever reducer).It is  used to treat different Medical conditions such as headache, muscle aches, arthritis, backache, toothaches, colds,menstrual periods and fevers.The FDA approved acetaminophen in 1951.

Paracetamol is a widely used analgesic and antipyretic drug. Paracetamol can be found in many over the counter medications such as Anacin®, Tylenol®, Panadol® Paracetamol suppositories (available in Thailand), Paralen® Paracetamol injection, Paracemol®, etc.

Paracetamol is a pharmacologically active ingredient that has analgesic and antipyretic activity, and hence it is also used in the treatment of pain and fever associated with infections, mild arthritic conditions, or headaches.

Paracetamol has less effect on inflammation than common anti-inflammatory drugs such as aspirin. Paracetamol is an analgesic, antipyretic and the best known of the commonly used over-the-counter (OTC) pain relievers in many countries. Paracetamol has become one of most widely used pharmaceutical agents.

Mechanism Of Action

Acetaminophen is assumed to act primarily within the central nervous system, increasing the pain threshold by inhibiting each isoforms of cyclooxygenase, COX-1, COX-2, and COX-3 enzymes involved in prostaglandin (PG) synthesis. in contrast to NSAIDs, acetaminophen doesn’t inhibit cyclooxygenase in peripheral tissues and, thus, has no peripheral anti-inflammatory affects. whereas acetylsalicylic acid acts as an irreversible inhibitor of COX and directly blocks the enzyme’s active site, studies have found that Tylenol indirectly blocks COX, and that this blockade is ineffective within the presence of peroxides. This would possibly make a case for why Tylenol is effective within the central nervous system and in endothelial cells however not in platelets and immune cells that have high levels of peroxides. Studies additionally report data suggesting that acetaminophen selectively blocks a variant of the COX enzyme that’s completely different from the known variants cox-1 and Cox-2. This enzyme is currently stated as COX-3. Its precise mechanism of action continues to be poorly understood, however future research could give any insight into how it works. The antipyretic properties of acetaminophen are possible as a result of direct effects on the heat-regulating centres of the hypothalamus leading to peripheral dilatation, sweating and thus temperature reduction.

Side Effects:

Paracetamol  usually has no side effects. If you have any unusual effects, contact your doctor or pharmacist promptly.

The most serious side effect is liverdamage due to overdoses, And The most common side effects are headache,rash And ,nausea .

Other important side effects include:

• Serious skin reactions
• Hypersensitivity reactions
• Anemia
• Reduced number of platelets in the blood (thrombocytopenia)
• Kidney damage

Usual Adult Dose for Pain

Doses may be given as a single or repeated dose as follows:

Oral:

• Immediate-release: 325 mg to 1 g orally every 4 to 6 hours
• Minimum Dosing Interval: every 4 hours
• Maximum Single Dose: 1000 mg
• Maximum Dose: 4 g per 24 hours
• Extended-Release: 1300 mg orally every 8 hours
• Maximum dose: 3900 mg per 24 hours

Parenteral:

• Weight less than 50 kg: 15 mg/kg IV every 6 hours OR 12.5 mg/kg IV every 4 hours
• Maximum Single Dose: 15 mg/kg
  Minimum Dosing Interval: every 4 hours
• Maximum Dose: 75 mg/kg per 24 hours
• Weight 50 kg or greater: 1000 mg IV every 6 hours OR 650 mg IV every 4 hours
• Maximum Single Dose: 1000 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Dose: 4000 mg per 24 hours

Rectal:

• 650 mg rectally every 4 to 6 hours
  Maximum dose: 3900 mg per 24 hours

Usual Adult Dose for Fever

Doses may be given as a single or repeated dose as follows:

Oral:

• Immediate-release: 325 mg to 1 g orally every 4 to 6 hours
• Minimum Dosing Interval: every 4 hours
• Maximum Single Dose: 1000 mg
• Maximum Dose: 4 g per 24 hours
• Extended-Release: 1300 mg orally every 8 hours
• Maximum dose: 3900 mg per 24 hours

Parenteral:

• Weight less than 50 kg: 15 mg/kg IV every 6 hours OR 12.5 mg/kg IV every 4 hours
• Maximum Single Dose: 15 mg/kg
• Minimum Dosing Interval: every 4 hours
• Maximum Dose: 75 mg/kg per 24 hours
• Weight 50 kg or greater: 1000 mg IV every 6 hours OR 650 mg IV every 4 hours
• Maximum Single Dose: 1000 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Dose: 4000 mg per 24 hours

Rectal:

• 650 mg rectally every 4 to 6 hours
  Maximum dose: 3900 mg per 24 hours

Pediatric Dose

Pain

Doses may be given as a single or repeated dose as follows:

ORAL:

• 10 to 15 mg/kg orally every 4 to 6 hours as needed not to exceed 5 doses in 24 hours
  -Alternatively, use weight first, then age:
• 2.7 to 5.3 kg (0 to 3 months): 40 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 5.4 to 8.1 kg (4 to 11 months): 80 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 8.2 to 10.8 kg (12 to 23 months): 120 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 10.9 to 16.3 kg (2 to 3 years): 160 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 16.4 to 21.7 kg (4 to 5 years): 240 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 21.8 to 27.2 kg (6 to 8 years): 320 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 27.3 to 32.6 kg (9 to 10 years): 400 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 32.7 to 43.2 kg (11 to 12 years): 480 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 12 years or older:immediate-release: 325 mg to 1 g orally every 4 to 6 hours
• Minimum Dosing Interval: every 4 hours
• Maximum Single Dose: 1000 mg
• Maximum Dose: 4 g per 24 hours
• Extended-Release: 1300 mg orally every 8 hours
• Maximum dose: 3900 mg per 24 hours

PARENTERAL:

• 2 to 12 years: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight less than 50 kg: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight 50 kg or greater: 650 mg IV every 4 hours OR 1000 mg IV every 6 hours
• Maximum Single Dose: 1000 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 4000 mg in 24 hours

RECTAL:

• 6 to 11 months: 80 mg rectally every 6 hours up to a maximum of 4 doses in 24 hours
• 12 to 36 months: 80 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 3 to 6 years: 120 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 6 to 12 years: 325 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 12 years or older: 650 mg rectally every 4 to 6 hours up to a maximum of 6 doses in 24 hours

Pediatric Dose

Fever

Doses may be given as a single or repeated dose as follows:

ORAL:

• 10 to 15 mg/kg orally every 4 to 6 hours as needed not to exceed 5 doses in 24 hours
  -Alternatively, use weight first, then age:
• 2.7 to 5.3 kg (0 to 3 months): 40 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 5.4 to 8.1 kg (4 to 11 months): 80 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 8.2 to 10.8 kg (12 to 23 months): 120 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 10.9 to 16.3 kg (2 to 3 years): 160 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 16.4 to 21.7 kg (4 to 5 years): 240 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 21.8 to 27.2 kg (6 to 8 years): 320 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 27.3 to 32.6 kg (9 to 10 years): 400 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 32.7 to 43.2 kg (11 to 12 years): 480 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 12 years or older:Immediate-release: 325 mg to 1 g orally every 4 to 6 hours
• Minimum Dosing Interval: every 4 hours
• Maximum Single Dose: 1000 mg
• Maximum Dose: 4 g per 24 hours

PARENTERAL:

• Neonates (premature neonates born at least 32 weeks gestational age up to 28 days chronological age): 12.5 mg/kg IV every 6 hours
• Minimum Dosing Interval: 6 hours
• Maximum Daily Dose: 50 mg/kg/day
• Infants (29 days to 2 years old): 15 mg/kg every 6 hours
• Minimum Dosing Interval: 6 hours
• Maximum Daily Dose: 60 mg/kg/day
• 2 to 12 years: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight less than 50 kg: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight 50 kg or greater: 650 mg IV every 4 hours OR 1000 mg IV every 6 hours
• Maximum Single Dose: 1000 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 4000 mg in 24 hours

RECTAL:

• 6 to 11 months: 80 mg rectally every 6 hours up to a maximum of 4 doses in 24 hours
• 12 to 36 months: 80 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 3 to 6 years: 120 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 6 to 12 years: 325 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 12 years or older: 650 mg rectally every 4 to 6 hours up to a maximum of 6 doses in 24 hours

Usual Pediatric Dose for Pain

Doses may be given as a single or repeated dose as follows:

ORAL:

• 10 to 15 mg/kg orally every 4 to 6 hours as needed not to exceed 5 doses in 24 hours
  -Alternatively, use weight first, then age:
• 2.7 to 5.3 kg (0 to 3 months): 40 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 5.4 to 8.1 kg (4 to 11 months): 80 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 8.2 to 10.8 kg (12 to 23 months): 120 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 10.9 to 16.3 kg (2 to 3 years): 160 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 16.4 to 21.7 kg (4 to 5 years): 240 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 21.8 to 27.2 kg (6 to 8 years): 320 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 27.3 to 32.6 kg (9 to 10 years): 400 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 32.7 to 43.2 kg (11 to 12 years): 480 mg orally every 4 hours as needed not to exceed 5 doses in 24 hours
• 12 years or older:Immediate-release: 325 mg to 1 g orally every 4 to 6 hours
• Minimum Dosing Interval: every 4 hours
• Maximum Single Dose: 1000 mg
• Maximum Dose: 4 g per 24 hours
• Extended-Release: 1300 mg orally every 8 hours
• Maximum dose: 3900 mg per 24 hours

PARENTERAL:

• 2 to 12 years: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight less than 50 kg: 12.5 mg/kg IV every 4 hours OR 15 mg/kg IV every 6 hours
• Maximum Single Dose: 15 mg/kg; not to exceed 750 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 75 mg/kg in 24 hours; not to exceed 3750 mg
• 13 years or older; weight 50 kg or greater: 650 mg IV every 4 hours OR 1000 mg IV every 6 hours
• Maximum Single Dose: 1000 mg
• Minimum Dosing Interval: every 4 hours
• Maximum Daily Dose: 4000 mg in 24 hours

RECTAL:

• 6 to 11 months: 80 mg rectally every 6 hours up to a maximum of 4 doses in 24 hours
• 12 to 36 months: 80 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 3 to 6 years: 120 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 6 to 12 years: 325 mg rectally every 4 to 6 hours up to a maximum of 5 doses in 24 hours
• 12 years or older: 650 mg rectally every 4 to 6 hours up to a maximum of 6 doses in 24 hours.

Paracetamol during pregnancy

Paracetamol has been used routinely during all stages of pregnancy to reduce a high temperature and for pain relief. There is no clear evidence that it has any harmful effects on an unborn baby.

Paracetamol is the preferred choice to treat The Following conditions during Pregnancy:

• High temperature (fever)
• Mild or moderate pain

However, as with any medication taken during pregnancy, use paracetamol at the lowest effective dose for the shortest possible time.

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