Phenagesic
Phenagesic Uses, Dosage, Side Effects, Food Interaction and all others data.
Paracetamol exhibits analgesic action by peripheral blockage of pain impulse generation. It produces antipyresis by inhibiting the hypothalamic heat-regulating centre. Its weak anti-inflammatory activity is related to inhibition of prostaglandin synthesis in the CNS.
Paracetamol (Acetaminophen) is thought to act primarily in the CNS, increasing the pain threshold by inhibiting both isoforms of cyclooxygenase, COX-1, COX-2, and COX-3 enzymes involved in prostaglandin (PG) synthesis. Unlike NSAIDs, acetaminophen does not inhibit cyclooxygenase in peripheral tissues and, thus, has no peripheral anti-inflammatory affects. While aspirin acts as an irreversible inhibitor of COX and directly blocks the enzyme's active site, studies have found that acetaminophen indirectly blocks COX, and that this blockade is ineffective in the presence of peroxides. This might explain why acetaminophen is effective in the central nervous system and in endothelial cells but not in platelets and immune cells which have high levels of peroxides. Studies also report data suggesting that acetaminophen selectively blocks a variant of the COX enzyme that is different from the known variants COX-1 and COX-2. This enzyme is now referred to as COX-3. Its exact mechanism of action is still poorly understood, but future research may provide further insight into how it works. The antipyretic properties of acetaminophen are likely due to direct effects on the heat-regulating centres of the hypothalamus resulting in peripheral vasodilation, sweating and hence heat dissipation.
Phenyltoloxamine is an antihistamine drug with sedative and analgesic effects. It is a H1 receptor blocker and a member of the ethanolamine class of antihistaminergic drugs. It is available in combination products that also contain other analgesics and antitussives such as acetaminophen. Phenyltoloxamine citrate is the more common salt form that acts as an active ingredient in pharmaceutical products and promotes hay fever relief via reversing the effects of histamine. Phenyltoloxamine acts as an adjuvant analgesic, which augments the analgesic effect of acetaminophen. It also potentiates the effects of other drugs, such as codeine and codeine derivatives.
Although phenyltoloxamine's ability to potentiate the effects of analgesics may be explained in part by its chemical nature as a first-generation H1 antihistamine that is capable of crossing the blood-brain barrier and causing tranquilizing effects at CNS histamine receptors, many of the drug's specific pharmacokinetics are not readily available - perhaps also because many early (phenyltoloxamine was involved in studies as early as the 1950s) first-generation antihistamines were not optimally investigated . Nevertheless, phenyltoloxamine is used to a fairly limited extent in contemporary medicine, with only very few products involving it as an active ingredient.
As a member of the first generation H1 antihistamines, it is known that phenyltoloxamine - like virtually all first generation H1 antihistamines - has a propensity for crossing the blood-brain barrier and acting on H1 histamine receptors there to interfere with neurotransmission . The most common results of this kind of first generation H1 antihistamine CNS neurotransmission interference are adverse effects like drowsiness, sedation, somnolence, and fatigue . Given these effects, under specific circumstances like a patient experiencing a pain or a cough that may be preoccupying all of their waking energy and attention, it is perhaps possible that the sedative and tranquilizing characteristics of phenyltoloxamine may be the factors that contribute to its apparent adjunctive analgesic and antitussive actions .
| Trade Name | Phenagesic |
| Generic | Paracetamol + phenyltoloxamine |
| Weight | 500mg + 30mg/15ml, 500mg + 30mg |
| Type | Oral liquid, oral tablet |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | United States |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Paracetamol IV is used for the management of mild to moderate pain, the management of moderate to severe pain with adjunctive opioid analgesics, the reduction of fever.
Paracetamol is a non-salicylate antipyretic and non-opioid analgesic agent. Paracetamol IV injection is a sterile, clear, colorless, non pyrogenic, isotonic formulation of Paracetamol intended for intravenous infusion.
Phenyltoloxamine is a medication used to treat minor aches and pains.
The primary therapeutic use for which phenyltoloxamine is currently indicated is as an adjuvant therapy in various combination products containing an analgesic(s) (either narcotic or non-narcotic), where it is expected to potentiate the pain relieving, anti-tussive, etc. effect(s) of the analgesic component of the product.
In that regard, some of these aforementioned combination products are typically indicated for the temporary relief of minor aches and pains like headache, muscular aches, backaches, minor arthritis pain, common cold, toothaches, menstrual cramps, etc ; or perhaps for the treatment of exhausting or non-productive cough, associated with cold or with upper respiratory allergic condition that does not respond to non-narcotic antitussives .
Phenagesic 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, BronchodilationBronchitis, Cough, Minor aches and pains, Airway secretion clearance therapy
How Phenagesic works
As a first-generation H1 antihistamine, phenyltoloxamine interferes with the agonist activity of histamine at the H1 receptor and are ostensibly used to attenuate inflammatory processes as a means to treat conditions like allergic rhinitis, allergic conjunctivitis, and urticaria . Reduction of the activity of the NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells) immune response transcription factor via the phospholipase C and phosphatidylinositol (PIP2) signaling pathways also serves to decrease antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors . Moreover, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release .
Additionally, first-generation antihistamines like phenyltoloxamine readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects, like nervousness and insomnia . By comparison, second-generation antihistamines are more selective for H1 receptors in the peripheral nervous system and do not cross the blood-brain barrier, resulting in fewer adverse drug effects overall .
Furthermore, although some studies propose that phenyltoloxamine may possess some intrinsic antispasmodic and distinct local anesthetic properties , the specific mechanisms of action for these effects have not been formalized. Also, even though the combination of phenyltoloxamine's ability to cross the blood-brain barrier and cause various tranquilizing effects may explain to some extent how it may be able to potentiate analgesic effects , there are also studies that observed no potentiating effects associated with phenyltoloxamine use either .
Dosage
Phenagesic dosage
Adults and adolescents weighing 50 kg and over: the recommended dosage of Paracetamol IV is 1000 mg every 6 hours or 650 mg every 4 hours, with a maximum single dose of Paracetamol IV of 1000 mg, a minimum dosing interval of 4 hours, and a maximum daily dose of Paracetamol of 4000 mg per day.
Adults and adolescents weighing under 50 kg: the recommended dosage of Paracetamol IV is 15 mg/kg every 6 hours or 12.5 mg/kg every 4 hours, with a maximum single dose of Paracetamol IV of 15 mg/kg, a minimum dosing interval of 4 hours, and a maximum daily dose of Paracetamol of 75 mg/kg per day.
Children >2 to 12 years of age: the recommended dosage of Paracetamol IV is 15 mg/kg every 6 hours or 12.5 mg/kg every 4 hours, with a maximum single dose of Paracetamol IV of 15 mg/kg, a minimum dosing interval of 4 hours, and a maximum daily dose of Paracetamol of 75 mg/kg per day.
Side Effects
As all paracetamol products, adverse drug reactions are rare (>1/10000, <1/1000) or very rare (<1/10000). Frequent adverse reactions at injection site have been reported during clinical trials (pain and burning sensation). Very rare cases of hypersensitivity reactions ranging from simple skin rash or urticaria to anaphylactic shock have been reported and require discontinuation of treatment. Cases of erythema, flushing, pruritus and tachycardia have been reported.
Toxicity
Toxicity after overdose may involve CNS effects like extreme drowsiness, lethargy, confusion, delirium, and coma in adults; paradoxical excitation, irritability, hyperactivity, insomnia, hallucinations, seizures, and respiratory depression or arrest in infants and young children, CNS adverse effects predominate o er cardiac adverse effects; death may occur within hours after ingestion of drug in untreated patients; rhabdomyolysis has also been reported .
Precaution
Administration of Paracetamol in doses higher than recommended may result in hepatic injury, including the risk of severe hepatotoxicity and death. Do not exceed the maximum recommended daily dose of Paracetamol. Use caution when administering Paracetamol in patients with the following conditions: hepatic impairment or active hepatic disease, alcoholism, chronic malnutrition, severe hypovolemia (e.g., due to dehydration or blood loss), or severe renal impairment (creatinine clearance < 30 ml/min). There were infrequent reports of life-threatening anaphylaxis requiring emergent medical attention. Discontinue Paracetamol IV immediately if symptoms associated with allergy or hypersensitivity occurs. Do not use Paracetamol IV in patients with Paracetamol allergy.
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.
Readily accessible data regarding the volume of distribution of phenyltoloxamine is not available. In fact, many first-generation H1 antihistamines have never had their pharmacokinetics (ie. absorption, distribution, metabolism, and elimination) optimally investigated .
Elimination Route
Readily accessible data regarding the absorption of phenyltoloxamine is not available. In fact, many first-generation H1 antihistamines have never had their pharmacokinetics (ie. absorption, distribution, metabolism, and elimination) optimally investigated .
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.
Readily accessible data regarding the half-life of phenyltoloxamine is not available. In fact, many first-generation H1 antihistamines have never had their pharmacokinetics (ie. absorption, distribution, metabolism, and elimination) optimally investigated .
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).
Readily accessible data regarding the clearance of phenyltoloxamine is not available. In fact, many first-generation H1 antihistamines have never had their pharmacokinetics (ie. absorption, distribution, metabolism, and elimination) optimally investigated .
Elimination Route
Readily accessible data regarding the primary route of elimination of phenyltoloxamine is not available. In fact, many first-generation H1 antihistamines have never had their pharmacokinetics (ie. absorption, distribution, metabolism, and elimination) optimally investigated .
Pregnancy & Breastfeeding use
Pregnancy Category C. There are no studies of intravenous Paracetamol in pregnant women; however, epidemiological data on oral Paracetamol use in pregnant women show no increased risk of major congenital malformations. Animal reproduction studies have not been conducted with IV Paracetamol and it is not known whether Paracetamol IV can cause fetal harm when administered to a pregnant woman. Paracetamol IV should be given to a pregnant woman only if clearly needed. There are no adequate and well-controlled studies with Paracetamol IV during labor and delivery; therefore, it should be used in such settings only after a careful benefit-risk assessment. While studies with Paracetamol IV have not been conducted, Paracetamol is secreted in human milk in small quantities after oral administration.
Contraindication
Paracetamol is contraindicated in patients with known hypersensitivity to its active ingredient or to any of the excipients in the intravenous formulation. Also contraindicated in patients with severe hepatic impairment or severe active liver disease
Special Warning
Pediatric Use: The safety and effectiveness of Paracetamol IV for the treatment of acute pain and fever in pediatric patients ages 2 years and older is supported by evidence from adequate and well-controlled studies of Paracetamol IV in adults.
Geriatric use: No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients.
Patients with Hepatic Impairment: Paracetamol is contraindicated in patients with severe hepatic impairment or severe active liver disease and should be used with caution in patients with hepatic impairment or active liver disease. A reduced total daily dose of Paracetamol may be warranted.
Patients with Renal Impairment: In cases of severe renal impairment (creatinine clearance < 30 ml/min), longer dosing intervals and a reduced total daily dose of Paracetamol may be warranted.
Storage Condition
Store in a cool & dry place & away from children. For single use only. The product should be used within 6 hours after opening. Do not refrigerate or freeze.
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