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tramadol hydrochloride

Brand

Ultram, Tramal

Availability

Tablets: 50 mg
Capsules
Syrup
Injectable (not available commercially in the USA)

Pharmacology

Tramadol hydrochloride is a synthetic, centrally acting, opiate agonist analgesic with a dual mode of action. It binds to opioid receptors modifying the transmission of pain impulses, and inhibits the reuptake of serotonin and norepinephrine. The efficacy and potency of tramadol is only five to ten times lower than that of morphine (Giusti et al, 1997). Although tramadol is a narcotic-like analgesic, it is not scheduled as a controlled substance by the U.S. FDA.

Tramadol has been shown to cause less respiratory depression and sedative effects than morphine. It also appears to have no effect on heart rate, left ventricular function, or cardiac index at dosages which are therapeutic. Unlike morphine, tramadol has not been shown to cause histamine release.

When given orally tramadol is almost completely absorbed. Rate and extent of absorption when given orally is not appreciably affected by the presence of food.

Distribution of tramadol in rats has been shown to cross the blood-brain barrier.

Tramadol is metabolized in the liver and excreted by the kidneys, with 52% of the drug unchanged, in dogs and rats.

Indications

Used for moderate to moderately severe post-op or injury-related pain, or where pain is present in chronic or terminal illness.

Drug Interactions or Contraindications

Tramadol should not be co-administered with selegiline or any other psychoactive class of medication such as selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (e.g. Clomicalm), monoamine oxidase inhibitors, other narcotic pain medicine, or tranquilizers (such as Valium). Consult veterinarian if co-administering with herbal medicines.

In animal studies, naloxone administration following Tramadol may potentiate the risk of convulsions.

Adverse Reactions

CNS:  sedation can occur at higher than therapeutic dosages.

CV:   bradycardia (decreased heart rate).

Respiratory:   decreased respiratory rate at higher than therapeutic dosages.

GI:   upset stomach (noted by signs of pica), constipation, and loss of appetite will cease when drug discontinued.

Skin:   itching.

*Note: In case of an overdose, signs that may appear include: respiratory depression, mental alteration, pinpoint pupils and seizures. Treatment for overdose is supportive care.

Dosage Recommendations

In animals, tramadol is removed from the body via liver and kidney excretion. Rats suffering from diseases in these systems should be monitored by a veterinarian, as it may be necessary to adjust the dose.

*Note: the tramadol dosage used in rats is empirical, and based on published dog/cat dosages. ²⁷*

1 mg/kg to 4 mg/kg, PO, SQ, BID  ³⁰. Dosage range used successfully in pet rats by Anthony Pilny, DVM, DABVP.

or

5 mg/kg, IM  ³⁴

or

5 mg/kg to 20 mg/kg, PO, SQ, q12hrs to q24hrs  ³⁴

Dosage to be used is based upon type and extent of pain involved. Use the lowest dose for condition being treated which achieves the desired effect.

Considerations

• Tramadol can be used separately or in combination with steroidal or non-steroidal anti-inflammatory drugs where deemed appropriate by the veterinarian.
• Oral dosing can be given with or without food; however, tramadol has a mildly bitter taste and mixing with something flavored will make it more palatable to the rat.
• Tablets should be stored in an airtight container at room temperature away from light.

Posted on September 20, 2010, 12:06, Last updated on May 16, 2012, 16:39 | Analgesics