Neogesic Rapid Forte

Uses

Methyl salicylate is a topical counter-irritant used for the symptomatic relief of acute musculoskeletal pain in the muscles, joints, and tendons.

Ointments or liniments containing methyl salicylate are applied topically as counter irritant for relief of acute pain associated with lumbago,sciatica and rheumatic conditions. Local analgesics for human and veterinary medicine.

Turpentine is a medication used to treat minor aches and pains of muscles and joints.

Turpentine has been used experimentally in a bath for the treatment of disseminated sclerosis and sexual dysfunction. It also has been studied for its antibacterial activity and inhibition of osteoclast activity. Turpentine is utilized in experimental models of inflammation to induce a systemic inflammatory immune response in animals.

Neogesic Rapid Forte is also used to associated treatment for these conditions: Acute Muscle Pain, Arthritis, Back Pain Lower Back, Backache, Contusions, Joint Pain, Ligament pain, Muscle Inflammation, Muscle Injuries, Muscle Strain, Muscle swelling, Pain, Pain of the Bone and Bones, Pain, Nerve, Partial-Onset Seizures, Postherpetic Neuralgia, Soreness, Muscle, Sprains, Tendon pain, Minor aches, Muscle, joint painsJoint Pain, Soreness, Muscle

How Neogesic Rapid Forte works

Counter-irritation is thought to be effective at alleviating musculoskeletal pain as the irritation of the sensory nerve endings is thought to alter or offset pain in the underlying muscle or joints that are served by the same nerves . This is thought to mask the underlying musculoskeletal pain and discomfort. When applied topically, methyl salicylate is thought to penetrate the skin and underlying tissues where it reversibly inhibits cyclooxygenase enzyme and locally and peripherally prevents the production of inflammatory mediators such as prostaglandin and thromboxane A2.

Binding of turpentine oil or inflammatory cytokines e.g. interleukin-1 (IL-1) activate signalling through the IL-1 Type 1 receptor (IL-1 R1). Initiation occurs by binding of Toll-interleukin 1 receptor adaptor protein (TIRAP) and Myeloid differentiation primary response gene 88 (mD88) which then dissociates and interacts with IRAK (Interleukin 1 receptor associated kinase) and the tumour necrosis factor receptor associated factor 6 (TRAF6). This activates the MAPK pathway leading to transcription of the nuclear factor κB transcription factor and production of inflammatory mediators.

Toxicity

Oral LD50 values (mg/kg) for mouse, rat and rabbit are 1110, 887 and 1300, respectively. Oral LD50 values for child and adult human (mg/kg) are 228 and 506, respectively. Although systemic toxicity from topical administration is rare, methyl salicylate can be absorbed in intract skin to cause stimulation of the central nervous system respiratory center, disturbance of lipid and carbohydrate metabolism, and disturbance of intracellular respiration. Severe toxicity can result in acute lung injury, lethargy, coma, seizures, cerebral edema, and death. In case of salicylate poisoning, the treatment consists of general supportive care, gastrointestinal decontamination with activated charcoal in cases of salicylate ingestion, and monitoring of serum salicylate concentrations. Bicarbonate infusions or hemodialysis can be used to achieve enhanced salicylate elimination .

Human : TCLo ( Inhalation) 175ppm, Effects : lung, Thorax or Respiration Human: TCLo ( inhalation ) 6gm/m3/3h , Effects : Behavioral: Headache Infant: LDLo ( Oral ) 1748 mg/kg, Effect : GI, Nausea or vomiting Man: LDLo (Oral ) 3mg/kg Mouse LC50 ( inhalation ) 29mg/m3/2h Mouse: LD50 ( intravenous ) 1180ug/kg Rabbit: LDLo ( Skin) 5010mg/kg, Effect: general depressed activity

Volume of Distribution

After absorption, methyl salicylate is distributed throughout most body tissues and most transcellular fluids, primarily by pH dependent passive processes. Salicylate is actively transported by a low-capacity, saturable system out of the CSF across the choroid plexus. The drug readily crosses the placental barrier.

Turpentine, as a lipophilic substance, accumulates in fatty tissues. The highest concentrations of turpentine following inhalation by rats were found in the spleen, kidneys, brain, and peripheral and perinephric fat.

Elimination Route

Approximately 12-20% of topically applied methyl salicylate may be systemically absorbed through intact skin within 10 hours of application, and absorption varies with different conditions such as surface area and pH. Dermal bioavailability is in the range of 11.8 – 30.7%. For the assessment of potential oral exposure to salicylates, bioavailability is assumed to be 100% .

Turpentine is readily absorbed from GI tract, skin, and respiratory tract.

Half Life

The plasma half-life for salicylate is 2 to 3 hr in low doses and about 12 hr at usual anti-inflammatory doses. The half-life of salicylate may be as long as 15 to 30 hr at high therapeutic doses or when there is intoxication.

Eight male volunteers were exposed to 450 mg/cu m turpentine by inhalation (2 hr, 50 W) in an exposure chamber. The mean half lives of the last phase of alpha-pinene, beta-pinene, and 3-carene (components of turpentine) averaged 32, 25, and 42 hours, respectively.

Elimination Route

Excreted by kidneys as free salicylic acid (10%), salicyluric acid (75%), salicylic phenolic (10%) and acyl glucuronide (5%), and gentisic acid (less than 1%).

Elimination of absorbed turpentine in the urine is manifested by an odor resembling that of violets.

Innovators Monograph

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