Acetaminophen 300 mg, Caffeine and 8 mg Codeine Phosphate

Uses

Acetaminophen is an analgesic drug used alone or in combination with opioids for pain management, and as an antipyretic agent.

In general, acetaminophen is used for the treatment of mild to moderate pain and reduction of fever. It is available over the counter in various forms, the most common being oral forms.

Acetaminophen injection is indicated for the management of mild to moderate pain, the management of moderate to severe pain with adjunctive opioid analgesics, and the reduction of fever.

Because of its low risk of causing allergic reactions, this drug can be administered in patients who are intolerant to salicylates and those with allergic tendencies, including bronchial asthmatics. Specific dosing guidelines should be followed when administering acetaminophen to children.

Caffeine is a stimulant present in tea, coffee, cola beverages, analgesic drugs, and agents used to increase alertness. It is also used in to prevent and treat pulmonary complications of premature birth.

Caffeine is indicated for the short term treatment of apnea of prematurity in infants and off label for the prevention and treatment of bronchopulmonary dysplasia caused by premature birth. In addition, it is indicated in combination with sodium benzoate to treat respiratory depression resulting from an overdose with CNS depressant drugs. Caffeine has a broad range of over the counter uses, and is found in energy supplements, athletic enhancement products, pain relief products, as well as cosmetic products.

Codeine is an opioid analgesic used to treat moderate to severe pain when the use of an opioid is indicated.

Codeine sulfate is a form of this drug that is commonly used. It is available in tablet form and indicated for the relief of mild to moderately severe pain, where the use of an opioid analgesic is appropriate .

The solution form is used by itself or combined in a syrup with other drugs and is used as a cough suppressant in adults aged 18 and above , .

Acetaminophen 300 mg, Caffeine and 8 mg Codeine Phosphate is also used to associated treatment for these conditions: Acute Gouty Arthritis, Acute Musculoskeletal Pain, Allergies, Ankylosing Spondylitis (AS), Arthritis, Chills, Cold, Cold Symptoms, Common Cold, Common Cold/Flu, Cough, Cough caused by Common Cold, Coughing caused by Flu caused by Influenza, Dyskinesia of the Biliary Tract, Dyskinesia of the Urinary Tract, Febrile Convulsions, Febrile Illness Acute, Fever, Fibromyalgia Syndrome, Flu caused by Influenza, Headache, Joint dislocations, Menstrual Distress (Dysmenorrhea), Mild pain, Muscle Inflammation, Muscle Injuries, Muscle Spasms, Musculoskeletal Pain, Nasal Congestion, Neuralgia, Osteoarthritis (OA), Pain, Pollen Allergy, Postoperative pain, Premenstrual cramps, Rheumatoid Arthritis, Rhinopharyngitis, Rhinorrhoea, Severe Pain, Sinusitis, Soreness, Muscle, Spasms, Spastic Pain of the Gastrointestinal Tract, Sprains, Tension Headache, Toothache, Upper Respiratory Tract Infection, Whiplash Syndrome, Acute Torticollis, Mild to moderate pain, Minor aches and pains, Minor pain, Moderate Pain, Airway secretion clearance therapy, Antispasmodic, BronchodilationBronchopulmonary Dysplasia (BPD), Common Cold, Dark circles under eyes, Dyspepsia, Fatigue, Fever, Flu caused by Influenza, Headache, Migraine, Pain, Pain, Acute, Pain, Menstrual, Primary apnea of premature newborns, Respiratory Depression, Rheumatic Pain, Somnolence, Soreness, Muscle, Tension Headache, Toothache, Moderate Pain, Analgesia, Antacid therapy, Athletic PerformanceCommon Cold, Cough, Flu caused by Influenza, Mild pain, Pain, Severe Pain, Dry cough, Moderate Pain, Upper respiratory symptoms, Airway secretion clearance therapy

How Acetaminophen 300 mg, Caffeine and 8 mg Codeine Phosphate works

According to its FDA labeling, acetaminophen's exact mechanism of action has not been fully established - despite this, it is often categorized alongside NSAIDs (nonsteroidal anti-inflammatory drugs) due to its ability to inhibit the cyclooxygenase (COX) pathways. It is thought to exert central actions which ultimately lead to the alleviation of pain symptoms.

One theory is that acetaminophen increases the pain threshold by inhibiting two isoforms of cyclooxygenase, COX-1 and COX-2, which are involved in prostaglandin (PG) synthesis. Prostaglandins are responsible for eliciting pain sensations. Acetaminophen does not inhibit cyclooxygenase in peripheral tissues and, therefore, has no peripheral anti-inflammatory effects. Though acetylsalicylic acid (aspirin) is an irreversible inhibitor of COX and directly blocks the active site of this enzyme, studies have shown that acetaminophen (paracetamol) blocks COX indirectly. Studies also suggest that acetaminophen selectively blocks a variant type of the COX enzyme that is unique from the known variants COX-1 and COX-2. This enzyme has been referred to as COX-3. The antipyretic actions of acetaminophen are likely attributed to direct action on heat-regulating centers in the brain, resulting in peripheral vasodilation, sweating, and loss of body heat. The exact mechanism of action of this drug is not fully understood at this time, but future research may contribute to deeper knowledge.

The mechanism of action of caffeine is complex, as it impacts several body systems, which are listed below. The effects as they relate to various body systems are described as follows:

General and cellular actions

Caffeine exerts several actions on cells, but the clinical relevance is poorly understood. One probable mechanism is the inhibition of nucleotide phosphodiesterase enzymes, adenosine receptors, regulation of calcium handling in cells, and participates in adenosine receptor antagonism. Phosphodiesterase enzymes regulate cell function via actions on second messengers cAMP and cGMP. This causes lipolysis through activation of hormone-sensitive lipases, releasing fatty acids and glycerol.

Respiratory

The exact mechanism of action of caffeine in treating apnea related to prematurity is unknown, however, there are several proposed mechanisms, including respiratory center stimulation in the central nervous system, a reduced threshold to hypercapnia with increased response, and increased consumption of oxygen, among others. The blocking of the adenosine receptors enhances respiratory drive via an increase in brain medullary response to carbon dioxide, stimulating ventilation and respiratory drive, while increasing contractility of the diaphragm.

Central nervous system

Caffeine demonstrates antagonism of all 4 adenosine receptor subtypes (A1, A2a, A2b, A3) in the central nervous system. Caffeine's effects on alertness and combatting drowsiness are specifically related to the antagonism of the A2a receptor.

Renal system

Caffeine has diuretic effects due to is stimulatory effects on renal blood flow, increase in glomerular filtration, and increase in sodium excretion.

Cardiovascular system

Adenosine receptor antagonism at the A1 receptor by caffeine stimulates inotropic effects in the heart. Blocking of adenosine receptors promotes catecholamine release, leading to stimulatory effects occurring in the heart and the rest of the body. In the blood vessels, caffeine exerts direct antagonism of adenosine receptors, causing vasodilation. It stimulates the endothelial cells in the blood vessel wall to release nitric oxide, potentiating blood vessel relaxation. Catecholamine release, however, antagonizes this and exerts inotropic and chronotropic effects on the heart, ultimately leading to vasoconstriction. Finally, caffeine is shown to raise systolic blood pressure measurements by 5 to 10 mmHg when it is not taken regularly, versus no effect in those who consume it regularly. The vasoconstricting effects of caffeine are beneficial in migraines and other types of headache, which are normally caused by vasodilation in the brain.

Codeine is a selective agonist for the mu opioid receptor, but with a much weaker affinity to this receptor than morphine, a more potent opioid drug. Codeine binds to mu-opioid receptors, which are involved in the transmission of pain throughout the body and central nervous system , . The analgesic properties of codeine are thought to arise from its conversion to Morphine, although the exact mechanism of analgesic action is unknown at this time , .

Toxicity

LD50 = 338 mg/kg (oral, mouse); LD50 = 1944 mg/kg (oral, rat)

Overdose and liver toxicity

Acetaminophen overdose may be manifested by renal tubular necrosis, hypoglycemic coma, and thrombocytopenia. Sometimes, liver necrosis can occur as well as liver failure. Death and the requirement of a liver transplant may also occur. Metabolism by the CYP2E1 pathway releases a toxic acetaminophen metabolite known as N-acetyl-p-benzoquinoneimine(NAPQI). The toxic effects caused by this drug are attributed to NAPQI, not acetaminophen alone.

Carcinogenesis

Long-term studies in mice and rats have been completed by the National Toxicology Program to study the carcinogenic risk of acetaminophen. In 2-year feeding studies, F344/N rats and B6C3F1 mice consumed a diet containing acetaminophen up to 6,000 ppm. Female rats showed evidence of carcinogenic activity demonstrated by a higher incidence of mononuclear cell leukemia at doses 0.8 times the maximum human daily dose (MHDD). No evidence of carcinogenesis in male rats (0.7 times) or mice (1.2 to 1.4 times the MHDD) was noted. The clinical relevance of this finding in humans is unknown.

Mutagenesis

Acetaminophen was not found to be mutagenic in the bacterial reverse mutation assay (Ames test). Despite this finding, acetaminophen tested positive in the in vitro mouse lymphoma assay as well as the in vitro chromosomal aberration assay using human lymphocytes. In published studies, acetaminophen has been reported to be clastogenic (disrupting chromosomes) when given a high dose of 1,500 mg/kg/day to the rat model (3.6 times the MHDD). No clastogenicity was observed at a dose of 750 mg/kg/day (1.8 times the MHDD), indicating that this drug has a threshold before it may cause mutagenesis. The clinical relevance of this finding in humans is unknown.

Impairment of Fertility

In studies conducted by the National Toxicology Program, fertility assessments have been performed in Swiss mice in a continuous breeding study. No effects on fertility were seen.

Use in pregnancy and nursing

The FDA label for acetaminophen considers it a pregnancy category C drug, meaning this drug has demonstrated adverse effects in animal studies. No human clinical studies in pregnancy have been done to this date for intravenous acetaminophen. Use acetaminophen only when necessary during pregnancy. Epidemiological data on oral acetaminophen use in pregnant women demonstrate no increase in the risk of major congenital malformations. While prospective clinical studies examining the results of nursing with acetaminophen use have not been conducted, acetaminophen is found secreted in human milk at low concentrations after oral administration. Data from more than 15 nursing mothers taking acetaminophen was obtained, and the calculated daily dose of acetaminophen that reaches the infant is about 1 to 2% of the maternal dose. Caution should be observed when acetaminophen is taken by a nursing woman.

The oral LD50 of caffeine in rats is 192 mg/kg. An acute fatal overdose of caffeine in humans is about 10–14 grams (equivalent to 150–200 mg/kg of body weight).

Caffeine overdose

In the case of caffeine overdose, seizures may occur, as caffeine is a central nervous system stimulant. It should be used with extreme caution in those with epilepsy or other seizure disorders. Symptoms of overdose may include nausea, vomiting, diarrhea, and gastrointestinal upset. Intoxication with caffeine is included in the World Health Organization’s International Classification of Diseases (ICD-10). Agitation, anxiety, restlessness, insomnia, tachycardia, tremors, tachycardia, psychomotor agitation, and, in some cases, death can occur, depending on the amount of caffeine consumed. Overdose is more likely to occur in individuals who do not consume caffeine regularly but consume energy drinks.

Overdose management

For a mild caffeine overdose, offer symptomatic treatment. In the case of a severe overdose, intubation for airway protection from changes in mental status or vomiting may be needed. Activated charcoal and hemodialysis can prevent further complications of an overdose and prevent absorption and metabolism. Benzodiazepine drugs can be administered to prevent or treat seizures. IV fluids and vasopressors may be necessary to combat hypotension associated with caffeine overdose. In addition, magnesium and beta blocking drugs can be used to treat arrhythmias that may occur, with defibrillation and resuscitation if the arrhythmias are lethal. Follow local ACLS protocols.

Oral LD50: 427 mg kg-1 (rat) .

Overdose/toxicity

Symptoms of opioid toxicity may include confusion, somnolence, shallow breathing, constricted pupils, nausea, vomiting, constipation and a lack of appetite. In severe cases, symptoms of circulatory and respiratory depression may ensue, which may be life-threatening or fatal , .

Teratogenic effects

This drug is classified as a pregnancy Category C drug. There are no adequate and well-controlled studies completed in pregnant women. Codeine should only be used during pregnancy if the potential benefit outweighs the potential risk of the drug to the fetus .

Codeine has shown embryolethal and fetotoxic effects in the hamster, rat as well as mouse models at about 2-4 times the maximum recommended human dose . Maternally toxic doses that were about 7 times the maximum recommended human dose of 360 mg/day, were associated with evidence of bone resorption and incomplete bone ossification. Codeine did not demonstrate evidence of embrytoxicity or fetotoxicity in the rabbit model at doses up to 2 times the maximum recommended human dose of 360 mg/day based on a body surface area comparison .

Nonteratogenic effects

Neonatal codeine withdrawal has been observed in infants born to addicted and non-addicted mothers who ingested codeine-containing medications in the days before delivery. Common symptoms of narcotic withdrawal include irritability, excessive crying, tremors, hyperreflexia, seizures, fever, vomiting, diarrhea, and poor feeding. These signs may be observed shortly following birth and may require specific treatment .

Codeine (30 mg/kg) given subcutaneously to pregnant rats during gestation and for 25 days after delivery increased the rate of neonatal mortality at birth. The dose given was 0.8 times the maximum recommended human dose of 360 mg/day .

The use in breastfeeding/nursing

Codeine is secreted into human milk. The maternal use of codeine can potentially lead to serious adverse reactions, including death, in nursing infants .

Volume of Distribution

Volume of distribution is about 0.9L/kg. 10 to 20% of the drug is bound to red blood cells. Acetaminophen appears to be widely distributed throughout most body tissues except in fat.

Caffeine has the ability to rapidly cross the blood-brain barrier. It is water and fat soluble and distributes throughout the body. Caffeine concentrations in the cerebrospinal fluid of preterm newborns are similar to the concentrations found in the plasma. The mean volume of distribution of caffeine in infants is 0.8-0.9 L/kg and 0.6 L/kg in the adult population.

Apparent volume of distribution: about 3-6 L/kg, showing an extensive distribution of the drug into tissues .

Elimination Route

Acetaminophen has 88% oral bioavailability and reaches its highest plasma concentration 90 minutes after ingestion. Peak blood levels of free acetaminophen are not reached until 3 hours after rectal administration of the suppository form of acetaminophen and the peak blood concentration is approximately 50% of the observed concentration after the ingestion of an equivalent oral dose (10-20 mcg/mL).

The percentage of a systemically absorbed rectal dose of acetaminophen is inconsistent, demonstrated by major differences in the bioavailability of acetaminophen after a dose administered rectally. Higher rectal doses or an increased frequency of administration may be used to attain blood concentrations of acetaminophen similar to those attained after oral acetaminophen administration.

Caffeine is rapidly absorbed after oral or parenteral administration, reaching peak plasma concentration within 30 minutes to 2 hours after administration. After oral administration, onset of action takes place within 45 to 1 hour. Food may delay caffeine absorption. The peak plasma level for caffeine ranges from 6-10mg/L. The absolute bioavailability is unavailable in neonates, but reaches about 100% in adults.

Absorption

Codeine is absorbed from the gastrointestinal tract. The maximum plasma concentration occurs 60 minutes after administration .

Food Effects

When 60 mg codeine sulfate was given 30 minutes post-ingestion of a high high-calorie meal, there was no significant change in the absorption of codeine .

Steady-state concentration

The administration of 15 mg codeine sulfate every 4 hours for 5 days lead to steady-state concentrations of codeine, morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) within 48 hours .

Half Life

The half-life for adults is 2.5 h after an intravenous dose of 15 mg/kg. After an overdose, the half-life can range from 4 to 8 hours depending on the severity of injury to the liver, as it heavily metabolizes acetaminophen.

In an average-sized adult or child above the age of 9, the half-life of caffeine is approximately 5 hours. Various characteristics and conditions can alter caffeine half-life. It can be reduced by up to 50% in smokers. Pregnant women show an increased half-life of 15 hours or higher, especially in the third trimester. The half-life in newborns is prolonged to about 8 hours at full-term and 100 hours in premature infants, likely due to reduced ability to metabolize it. Liver disease or drugs that inhibit CYP1A2 can increase caffeine half-life.

Plasma half-lives of codeine and its metabolites have been reported to be approximately 3 hours .

Clearance

Adults: 0.27 L/h/kg following a 15 mg/kg intravenous (IV) dose. Children: 0.34 L/h/kg following a 15 mg/kg intravenous (IV dose).

The clearance of caffeine varies, but on average, is about 0.078 L/kg/h (1.3 mL/min/kg).

Renal clearance of codeine was 183 +/- 59 ml min-1 in a clinical study .

Renal impairment may decrease codeine clearance .

Elimination Route

Acetaminophen metabolites are mainly excreted in the urine. Less than 5% is excreted in the urine as free (unconjugated) acetaminophen and at least 90% of the administered dose is excreted within 24 hours.

The major metabolites of caffeine can be found excreted in the urine. About 0.5% to 2% of a caffeine dose is found excreted in urine, as it because it is heavily absorbed in the renal tubules.

About 90% of the total dose of codeine is excreted by the kidneys. Approximately 10% of the drug excreted by the kidneys is unchanged codeine .

The majority of the excretion products can be found in the urine within 6 hours of ingestion, and 40-60 % of the codeine is excreted free or conjugated, approximately 5 to 15 percent as free and conjugated morphine, and approximately 10-20% free and conjugated norcodeine .

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