Auro-Tramadol/Acetaminophen

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.

Tramadol is used for the treatment of moderate to severe painful conditions. These include: Postoperative pain, Colic and spastic pain, Cancer pain, Joint pain, Neck and back pain & Pain associated with osteoporosis.

Auro-Tramadol/Acetaminophen 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, BronchodilationPain, Acute, Premature Ejaculation, Severe Pain, Acute, moderate, severe Pain, Moderate Pain

How Auro-Tramadol/Acetaminophen 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.

Tramadol is a centrally acting μ-opioid receptor agonist and SNRI (serotonin/norepinephrine reuptake-inhibitor) that is structurally related to codeine and morphine. Tramadol binds weakly to κ- and δ-opioid receptors and to the μ-opioid receptor with 6000-fold less affinity than morphine.

Tramadol exists as a racemic mixture consisting of two pharmacologically active enantiomers that both contribute to its analgesic property through different mechanisms: (+)-tramadol and its primary metabolite (+)-O-desmethyl-tramadol (M1) are agonists of the μ opioid receptor while (+)-tramadol inhibits serotonin reuptake and (-)-tramadol inhibits norepinephrine reuptake. These pathways are complementary and synergistic, improving tramadol's ability to modulate the perception of and response to pain.

In animal models, M1 is up to 6 times more potent than tramadol in producing analgesia and 200 times more potent in μ-opioid binding.

Tramadol has also been shown to affect a number of pain modulators including alpha2-adrenoreceptors, neurokinin 1 receptors, the voltage-gated sodium channel type II alpha subunit, transient receptor potential cation channel subfamily V member 1 (TRPV1 - also known as the capsaicin receptor), muscarinic receptors (M1 and M3), N-methyl-D-aspartate receptor (also known as the NMDA receptor or glutamate receptor), Adenosine A1 receptors, and nicotinic acetylcholine receptor.

In addition to the above neuronal targets, tramadol has a number of effects on inflammatory and immune mediators involved in the pain response. This includes inhibitory effects on cytokines, prostaglandin E2 (PGE2), nuclear factor-κB, and glial cells as well as a change in the polarization state of M1 macrophages.

Dosage

Auro-Tramadol/Acetaminophen dosage

Capsule or Tablet: Usual doses are 50 to 100 mg every four to six hours. For acute pain an initial dose of 100 mg is required. For chronic painful conditions an initial dose of 50 mg is recommended. Subsequent doses should be 50 to 100 mg administered 4-6 hourly. The dose level and frequency of dosing will depend on the severity of the pain.The total daily dosage by mouth should not exceed 400 mg.

Sustained Release Capsuleor Tablet: One SR capsuleor tablet every 12 hours, for example first one in the morning and then at the same time in the evening. The number of capsules taken at a time will depend upon severity of pain, but it should not be taken more frequently than every 12 hours.The total daily dosage by mouth should not exceed 400 mg.

Injection: A dose of 50-100 mg may be given every 4 to 6 hours by intramuscular or by intravenous infusion. For the treatment of postoperative pain,the initial dose is 100 mg followed by 50 mg every 10 to 20 minutes if necessary to a maximum of 250 mg in the first hour. Thereafter, doses are 50 to 100 mg every 4 to 6 hours up to a total daily dose of 600 mg.

Suppository: Tramadol suppository should be administered rectally. For adults usual dose is 100 mg Tramadol Hydrochloride 6 hourly. In general, 400 mg Tramadol Hydrochloride (4 Tramadol suppository) per day sufficient. However, for the treatment of Cancer pain and severe pain after operations much higher daily doses can be used.

Side Effects

Commonly occurring side-effects are dizziness/vertigo, nausea, constipation, headache, somnolence, vomiting, pruritus, CNS stimulation, asthenia, sweating, dyspepsia, dry mouth, diarrhoea.

Less commonly occurring side-effects include malaise, allergic reaction, weight loss, vasodilatation, palpitations, abdominal pain, anorexia, flatulence, GI bleeding, hepatitis, stomatitis etc.

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 reported LD50 for tramadol, when administered orally in mice, is 350 mg/kg.

In carcinogenic studies, there are reports of murine tumors which cannot be concluded to be carcinogenic in humans. On the other hand, tramadol showed no evidence to be mutagenic in different assays and does not have effects on fertility. However, there are clear reports of embryotoxicity and fetotoxicity.

Precaution

Respiratory depression: When large doses of tramadol are administered with anaesthetic with anaesthetic medications or alcohol, respiratory depression may result. Therefore, tramadol should be administered cautiously in patients at risk for respiratory depression.

Opioid dependence: Tramadol is not recommended for patients who are dependent on opioids.

Concomitant CNS depressants: Tramadol should be used with caution and in reduced dosages when administering to patients receiving CNS depressants such as alcohol, opioids, anesthetic agents, phenothiazines, tranquilizers or sedative hypnotics.

Concomitant MAO inhibitors: Tramadol should be used with great caution in patients taking MAO inhibitors, since tramadol inhibits the uptake of norepinephrine and serotonin.

Tramadol should be used with caution in patients with increased intracranial pressure or head injury and patients with acute abdominal conditions.

Interaction

In general, physician need not be concerned about drugs interacting with Tramadol. The monoamine oxidase (MAO) inhibitors represent the only drug class not recommended for combination with Tramadol. Concomitant administration of carbamazepine with Tramadol causes a significant increase in Tramadol metabolism and it requires to increase the dose of Tramadol.

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.

The volume of distribution of tramadol is reported to be in the range of 2.6-2.9 L/kg. Tramadol has high tissue affinity; the total volume of distribution after oral administration was 306L and 203L after parenteral administration. Tramadol crosses the blood-brain barrier with peak brain concentrations occurring 10 minutes following oral administration. It also crosses the placental barrier with umbilical concentrations being found to be ~80% of maternal concentrations.

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.

Oral Administration

Tramadol is administered as a racemate, with both the [-] and [+] forms of both tramadol and the M1 metabolite detected in circulation. Following administration, racemic tramadol is rapidly and almost completely absorbed, with a bioavailability of 75%. This difference in absorption and bioavailability can be attributed to the 20-30% first-pass metabolism. Peak plasma concentrations of tramadol and the primary metabolite M1 occur at two and three hours, respectively. Following a single oral dose of 100mg of tramadol, the Cmax was found to be approximately 300μg/L with a Tmax of 1.6-1.9 hours, while metabolite M1 was found to have a Cmax of 55μg/L with a Tmax of 3 hours.

Steady-state plasma concentrations of both tramadol and M1 are achieved within two days of dosing. There is no evidence of self-induction. Following multiple oral doses, Cmax is 16% higher and AUC is 36% higher than after a single dose, demonstrating a potential role of saturable first-pass hepatic metabolism in increasing bioavailability.

Intramuscular Administration

Tramadol is rapidly and almost completely absorbed following intramuscular administration. Following injection of 50mg of tramadol, Cmax of 166μg/L was found with a Tmax of 0.75 hours.

Rectal Administration

Following rectal administration with suppositories containing 100mg of tramadol, Cmax of 294μg/L was found with a Tmax of 3.3 hours. The absolute bioavailability was found to be higher than oral administration (77% vs 75%), likely due to reduced first-pass metabolism with rectal administration compared to oral administration.

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.

Tramadol reported a half-life of 5-6 hours while the M1 metabolite presents a half-life of 8 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).

In clinical trials, the clearance rate of tramadol ranged from 3.73 ml/min/kg in renal impairment patients to 8.50 ml/min/kg in healthy adults.

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.

Tramadol is eliminated primarily through metabolism by the liver and the metabolites are excreted primarily by the kidneys, accounting for 90% of the excretion while the remaining 10% is excreted through feces. Approximately 30% of the dose is excreted in the urine as unchanged drug, whereas 60% of the dose is excreted as metabolites.

The mean terminal plasma elimination half-lives of racemic tramadol and racemic M1 are 6.3 ± 1.4 and 7.4 ± 1.4 hours, respectively. The plasma elimination half-life of racemic tramadol increased from approximately six hours to seven hours upon multiple dosing.

Pregnancy & Breastfeeding use

Safe use of Tramadol in pregnancy has not been established. Tramadol has been shown to cross the placenta. There are no adequate and well-controlled studies in pregnant women. Therefore, Tramadol should be used during pregnancy only if the potential benefit justifies the risk to the foetus. Tramadol Hydrochloride should not be administered during breast feeding as Tramadol and its metabolites have been detected in breast milk.

Contraindication

Tramadol is contraindicated in persons having hypersensitivity to this drug. It is also contraindicated in acute intoxication with alcohol, hypnotics, centrally acting analgesics, opioids or psychotropic drugs.

Special Warning

Paediatric use: The paediatric use of Tramadol is not recommended because safety and efficacy in patients under 16 years of age have not been established.

Use in children: Use in children from the age of 1 year Tramadol Hydrochloride can be given in a dose of 1-2 mg/kg body weight. However,suppository (100 mg Tramadol Hydrochloride) should not be administered in children and adolescents below the age of 14 years. Tramadol Hydrochloride 100 mg SR Capsules have not been studied in children. Therefore,safety and efficacy have not been established and the product should not be used in children.

Renal Impairment: Oral:

• CrCl <10: Contraindicated.
• CrCl 10 to <30: Increase dosing interval to 12. Max: 200 mg/day; Contraindicated (extended-release tab).

Parenteral:

• CrCl <10: Contraindicated.
• CrCl 10-30: Increase dosing interval to 12 hrly.

Hepatic Impairment:

• Oral: Severe: Increase dosing interval to 12 hrly; Contraindicated (extended-release).
• Parenteral: Severe: Increase dosing interval to 12 hrly.

Storage Condition

Store below 30° C, protected from light and moisture. Keep all medicines out of reach of children.

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