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Trimeperidine (Promedol)

Trimeperidinum

For medical students2 min readUpdated 2026-10-10

Trimeperidine (also known as promedol) is a synthetic opioid analgesic derived from phenylpiperidine. It effectively relieves severe pain while differing from classical opiates by possessing a smooth muscle relaxant component and causing less respiratory center depression.

Chemical natureSynthetic N-methylpiperidine (phenylpiperidine) derivative

Respiratory centerDepresses respiration significantly less than morphine

Smooth muscleExerts a spasmolytic effect on the bronchi and ureters

Analgesic potency2–4 times less potent than morphine

Pharmacodynamics: Comparison with the Standard

The synthetic opioid analgesic trimeperidine (Trimeperidinum) is an N-methylpiperidine derivative. In clinical pharmacology, this drug is traditionally compared to the reference opioid, morphine. In terms of analgesic potency, trimeperidine is 2–4 times weaker than morphine, but it possesses several clinically significant advantages.

Chief among these is its safety profile regarding the respiratory system. The drug causes significantly less depression of the respiratory center. This critically important property allows for its use in pediatric practice and obstetric analgesia. The pharmacokinetic parameters of trimeperidine are otherwise almost identical to those of morphine.

Effects on Smooth Muscle and Myometrium

A crucial pharmacodynamic difference between trimeperidine and morphine lies in its effect on smooth muscle structures. While classical opiates have a pronounced spasmogenic effect, trimeperidine exerts a spasmolytic action on the smooth muscle of the bronchial tree and ureters.

Regarding the intestines and biliary tract, a spasmogenic effect is present, but it is considerably less pronounced. The drug's effect on the female reproductive system is also noteworthy: trimeperidine specifically increases myometrial tone and stimulates its contractility.

Indications for Use

The specific pharmacological profile of trimeperidine dictates a wide range of clinical applications:

Severe pain syndrome: relief of pain in severe trauma, oncological diseases, and the postoperative period.
Obstetric analgesia: the drug is a preferred agent due to its safety for the fetal respiratory center and its ability to stimulate myometrial contractions.
Relief of colic: used for renal and biliary colic because it not only relieves pain but also eliminates smooth muscle spasms via its spasmolytic component.
Premedication: pharmacological preparation of patients for surgical interventions.

Adverse Reactions and Contraindications

Like all opioid analgesics, trimeperidine has several serious side effects. Its use may cause dyspeptic disorders (nausea, vomiting), general weakness, and dizziness. The most serious problem remains the risk of developing drug dependence — both psychological and physical.

An absolute contraindication to prescribing trimeperidine is the presence of respiratory failure in the patient, since, despite its milder action compared to morphine, the drug is still capable of depressing the respiratory center.

Mnemonic

PROMEDOL: Pain relief, Relaxes ureters, Obstetrics analgesia, Minimal respiratory depression, Less potent than morphine.

Frequently asked questions

What side effects does trimeperidine cause?

Trimeperidine causes several adverse reactions characteristic of opioid analgesics. The main side effects include:

Dyspeptic disorders — nausea and vomiting.
Neurological disturbances — general weakness and dizziness.
Respiratory depression — the drug suppresses the respiratory center, requiring caution in respiratory disorders.
Drug dependence — both psychological and physical dependence can develop with prolonged use.

What are the contraindications to trimeperidine?

There are several strict contraindications based on its pharmacodynamic features. The drug is contraindicated in the following cases:

Respiratory failure — due to the drug's ability to depress the respiratory center.
Early childhood — trimeperidine is absolutely contraindicated in children under 2 years of age.

Additionally, the drug should be used with caution in elderly patients and those with existing respiratory impairments.

What are the routes of administration for trimeperidine?

Trimeperidine is administered intramuscularly and intravenously. Intramuscular administration is used, in particular, for severe pain and as part of premedication. Intravenous administration is used for severe pain syndromes, including analgesia during cesarean sections, as well as in traumatic shock.

Why is trimeperidine preferred over morphine in renal colic?

Unlike morphine, which causes severe smooth muscle spasm, trimeperidine exerts a spasmolytic effect on the ureters, which helps facilitate stone passage and relieve pain.

Can promedol be used for labor analgesia?

Yes, this is one of its key indications. It increases myometrial tone and contractility while causing less respiratory depression, making it safer for the fetus.

How much weaker is trimeperidine than morphine?

In terms of analgesic effect, trimeperidine is approximately 2–4 times less potent than morphine.

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