Tramadol

Tramadol is a painkiller from the group of opioid analgesics. It is used to treat moderate to severe pain. Due to its better tolerability compared to other opioids, tramadol is considered a "low risk" opioid. Indications for use include: Post-surgery pain, injury, or chronic pain. Tramadol is often given as a tablet or capsule, but can also be given as a suppository or intravenously. As with all opioids, there is a potential for dependence associated with its use. Tramadol is available only on prescription.

Pharmacodynamics

Tramadol achieves its main effect via an agonistic (activating) action at the so-called μ-opioid receptor. Tramadol also binds weakly to the other two known opioid receptors. In doing so, its affinity is 6000 times lower than that of morphine. By binding to these receptors, the perception of pain is dampened. However, tramadol has a second mechanism of action that is partly responsible for pain relief. Tramadol inhibits the reuptake of serotonin and norepinephrine into the presynapse, permanently increasing their concentration in the synaptic cleft. Both neurotransmitters are involved in pain transmission. As a result, pain is further additionally alleviated and mood is improved (antidepressant effect).

Pharmacokinetics

Tramadol is rapidly and almost completely absorbed via the gastrointestinal tract. The bioavailability is about 75%. The maximum plasma concentration of tramadol (after oral administration) is normally reached after 1-2 hours. Only 20% of the given dose is bound to plasma proteins. Tramadol is metabolized in the liver into at least 23 different metabolites. The enzyme that catalyzes these reactions is CYP2D6. 90% of the dose is ultimately excreted by the kidneys. the remaining 10% is excreted by the body in the stool. The elimination half-life is 5-6 hours.

Drug interactions

Taking it together with bupropion or MAO inhibitors may cause serious side effects. In addition, concomitant use of centrally depressant substances, benzodiazepines, carbamazepine, anticoagulants and substances that increase serotonin levels (antidepressants, cocaine, ecstasy) should be avoided.

Side effects

Common side effects include:

• Headache
• Nausea
• Constipation
• Fatigue
• Sweating
• Dry mouth

There is a risk of dependence associated with the use of tramadol.

Toxicological data

LD50 (mouse, oral): 350 mg/kg