acetaminophen rectal

Action and Spectrum

Actions and Spectrum: 

• acetaminophen is a widely used analgesic (pain reliever) and antipyretic (fever reducer). When administered rectally, acetaminophen is absorbed into the bloodstream through the rectal mucosa. The mechanism of action of acetaminophen is believed to involve the inhibition of prostaglandin synthesis in the central nervous system. 
• acetaminophen is thought to work primarily by inhibiting the cyclooxygenase (COX) enzymes, particularly COX-2, responsible for synthesizing prostaglandins. Prostaglandins are chemical messengers in the body that play a role in inflammation, pain, and fever. By inhibiting their production, acetaminophen helps to reduce pain and fever. 
• Unlike nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or aspirin, acetaminophen has little anti-inflammatory activity. It primarily acts on the central nervous system, specifically in the hypothalamus, to reduce fever. Additionally, its analgesic effects are believed to involve modulation of the endogenous cannabinoid system and activation of descending serotonergic pathways. 
• The spectrum of activity of acetaminophen is mainly limited to its analgesic and antipyretic properties. It is commonly used to relieve mild to moderate pain, such as headaches, muscle aches, toothaches, and pain associated with common colds and flu. It is also effective in reducing fever in both children and adults. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Urticaria 

Angioedema 

Nephrotoxicity (chronic overdose) 

Decrease in chloride, glucose, uric acid 

Agranulocytosis 

Leukopenia 

Pancytopenia 

Thrombocytopenic purpura 

Pruritic maculopapular rash 

Rectal discomfort 

Increase in bilirubin 

Analgesic nephropathy 

Laryngeal edema 

Decrease in bicarbonate, sodium, calcium 

Neutropenia 

Thrombocytopenia 

Anaphylactoid reaction 

Black Box Warning

Black box warning: 

None 

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

• Hypersensitivity or Allergy: Individuals with known hypersensitivity or allergy to acetaminophen or its components should avoid using acetaminophen rectal suppositories. Allergic reactions can range from mild skin rashes to severe symptoms like difficulty breathing and anaphylaxis. 
• Liver Disease: acetaminophen is primarily metabolized in the liver, and individuals with severe liver disease or active liver dysfunction should exercise caution when using acetaminophen. High doses or prolonged use of acetaminophen can cause liver damage. It is important to consult a healthcare professional for appropriate dosage adjustments. 
• Severe Renal Impairment: The kidneys primarily eliminate acetaminophen from the body. Individuals with severe renal impairment or end-stage renal disease may require dosage adjustments to prevent the accumulation of acetaminophen metabolites, which can be toxic to the kidneys. 
• Alcohol Use Disorder: Chronic excessive alcohol consumption can increase the risk of liver damage when combined with acetaminophen. Individuals with alcohol use disorder or a history of alcohol-related liver disease should use acetaminophen cautiously and follow the recommended dosage. 
• G6PD Deficiency: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an inherited condition affecting red blood cells. Certain medications, including acetaminophen, can trigger hemolysis (breakdown of red blood cells) in individuals with G6PD deficiency. Therefore, it is essential to avoid acetaminophen in individuals with known G6PD deficiency. 
• Pre-existing Medical Conditions: Individuals with certain medical conditions, such as severe anemia, respiratory depression, or severe dehydration, may need to avoid acetaminophen rectal suppositories due to potential risks associated with these conditions. 

Caution: 

• Correct Dosage: Following the recommended dosage instructions provided by a healthcare professional or indicated on the product packaging is crucial. Too much acetaminophen can lead to overdose, which can cause liver damage. Ensure you know the appropriate dose based on age, weight, and individual circumstances. 
• Drug Interactions: acetaminophen can interact with certain medications, such as warfarin (an anticoagulant), phenytoin (an anticonvulsant), and certain antibiotics.  
• Alcohol Consumption: Combining acetaminophen with alcohol can increase the risk of liver damage. It is advisable to avoid or limit alcohol consumption while using acetaminophen rectal suppositories. 
• Pediatric use: acetaminophen rectal suppositories may be used in children, but it is essential to follow age-specific dosing instructions and consult with a pediatrician for appropriate use. 
• Side Effects: Although rare, acetaminophen can cause side effects such as skin rash, itching, or allergic reactions. If you experience any unusual or severe reactions after using acetaminophen rectal suppositories, seek medical attention immediately. 

Pregnancy / Lactation

Pregnancy consideration: It is generally considered safe for short-term use during all stages of pregnancy 

Pregnancy Category: B 

Lactation: Excretion of the drug in human breast milk is known 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacology: 

The pharmacology of acetaminophen rectal suppositories is like that of oral acetaminophen. acetaminophen, or paracetamol, is a widely used analgesic (pain reliever) and antipyretic (fever reducer). 

After administering an acetaminophen rectal suppository, the drug is absorbed into the bloodstream through the rectal mucosa. From there, it is distributed throughout the body, including the central nervous system (CNS). acetaminophen’s primary site of action is believed to be in the CNS, particularly in the hypothalamus, which helps regulate body temperature. 

Pharmacodynamics: 

The pharmacodynamics of acetaminophen rectal suppositories are primarily related to its analgesic (pain-relieving) and antipyretic (fever-reducing) effects.  

• Inhibition of Prostaglandin Synthesis: acetaminophen is believed to primarily inhibit the synthesis of prostaglandins, particularly in the CNS. Prostaglandins are lipid compounds that play a role in pain, inflammation, and fever. By inhibiting the cyclooxygenase (COX) enzymes, especially COX-2, acetaminophen reduces the production of prostaglandins. This leads to analgesic and antipyretic effects. 
• Activation of Descending Serotonergic Pathways: acetaminophen has been shown to activate descending serotonergic pathways in the CNS. These pathways involve the release of serotonin, a neurotransmitter involved in the modulation of pain perception. By enhancing the release of serotonin, acetaminophen contributes to its analgesic effects. 
• Modulation of the Endogenous Cannabinoid System: acetaminophen has been found to modulate the endogenous cannabinoid system, explicitly affecting the cannabinoid CB1 receptor. This modulation can result in analgesic effects, although the precise mechanisms are not fully understood. 
• Hypothalamic Effects on Body Temperature: acetaminophen acts on the hypothalamus, a brain region that regulates body temperature. By exerting its effects on the hypothalamus, acetaminophen helps to reduce fever. 

Pharmacokinetics: 

Absorption 

After administering an acetaminophen rectal suppository, the drug is absorbed into the bloodstream through the rectal mucosa. The suppository dissolves, releasing the drug, which is then taken up by the blood vessels in the rectal area. From there, it enters the systemic circulation and is transported throughout the body. 

Distribution 

acetaminophen is well distributed throughout the body, including various tissues and organs. It crosses the blood-brain barrier, allowing it to reach the central nervous system (CNS). It also crosses the placenta, which can reach the fetus during pregnancy. Acetaminophen is primarily distributed in the blood plasma, and its concentration decreases over time as it undergoes metabolism. 

Metabolism 

acetaminophen is primarily metabolized in the liver through various pathways. The major metabolic pathways involve conjugation with glucuronic acid (glucuronidation) and sulfuric acid (sulfation) to form inactive metabolites. These metabolites are then eliminated from the body through urine. 

However, a small portion of acetaminophen is metabolized by the cytochrome P450 enzyme system, particularly the CYP2E1 enzyme, to form a reactive metabolite called N-acetyl-p-benzoquinone imine (NAPQI). Under normal conditions, NAPQI is rapidly detoxified by the liver’s antioxidant system, primarily glutathione, and excreted harmlessly. However, when the detoxification pathways are overwhelmed, NAPQI can accumulate and cause liver damage.  

Elimination and Excretion 

Most metabolites of acetaminophen, including the inactive glucuronide and sulfate conjugates, are excreted in the urine. Only a tiny amount of the drug and its metabolites are excreted in the feces. The elimination half-life of acetaminophen is approximately 2 to 3 hours in adults but can be prolonged in individuals with liver or kidney impairment. 

Adminstartion

Administration: 

acetaminophen rectal suppositories are administered through the rectum. Here are the general steps for the administration of acetaminophen rectal suppositories: 

• Wash your hands thoroughly with soap and water to ensure cleanliness. 
• Remove the suppository from its packaging. If the suppository is too soft due to heat, you may need to refrigerate it briefly to firm it up before removal from the wrapper. Be careful not to freeze it. 
• Find a comfortable position. You can lie on your side with one leg bent towards your chest or your stomach with your knees bent. 
• Gently insert the suppository into the rectum using your finger or an applicator provided with the suppository. The tapered end should go in first. Inserting it past the sphincter muscle and into the rectum is essential. 
• Once the suppository is inserted, keep lying down for a few minutes to allow it to dissolve and be absorbed. Avoid any activities that may cause the suppository to be expelled. 
• After administration, wash your hands thoroughly again to remove any residual medication. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: acetaminophen rectal 

Why do we use acetaminophen rectal? 

acetaminophen rectal suppositories are primarily used for the same purposes as oral acetaminophen. Here are some common uses: 

• Pain Relief: acetaminophen rectal suppositories can relieve mild to moderate pain, such as headache, toothache, muscle aches, menstrual cramps, and pain associated with minor injuries. 
• Fever Reduction: acetaminophen rectal suppositories also reduce fever in adults and children. 
• Pain and Fever in Children: acetaminophen rectal suppositories may be used in children who cannot take oral medications due to vomiting, difficulty swallowing, or other reasons. It provides an alternative medication delivery method for pain relief and fever reduction.