**Question:** Which of the following drugs are believed to be effective in the treatment of post-operative shivering?

*Core Concept*: Post-operative shivering is a common complication following general anesthesia, characterized by involuntary muscle contractions and heat production, which can lead to increased oxygen consumption and heat loss. The aim of treatment is to counteract these effects and maintain body temperature.

**Why the Correct Answer is Right:**
A. Dipyrone (Metamizole): Dipyrone is an analgesic and antipyretic drug that acts as a cyclooxygenase inhibitor, suppressing prostaglandin synthesis. This results in decreased heat production and reduced shivering.
B. Levomepromazine: Levomepromazine is a phenothiazine neuroleptic drug used as an antiemetic and antipsychotic agent. It acts on dopaminergic receptors in the hypothalamus, suppressing the thermoregulatory center and reducing shivering.
C. Ondansetron: Ondansetron is a selective serotonin receptor antagonist primarily used as an antiemetic. Although it does not directly target shivering, it can indirectly reduce shivering by controlling nausea and vomiting, which may lead to improved hydration and nutrition, and better overall patient comfort.
D. Haloperidol: Haloperidol is a dopamine antagonist primarily used as an antipsychotic and antiemetic agent. Like levomepromazine, it affects the hypothalamic thermoregulatory center, reducing shivering.

**Why Each Wrong Option is Incorrect:**
A. Dipyrone: Although dipyrone is effective in reducing shivering, its use is limited due to its potential for causing severe bone marrow suppression.
B. Ondansetron: Although ondansetron may indirectly reduce shivering, it is not primarily designed for this purpose.
C. Haloperidol: Haloperidol is a dopamine antagonist, but its use for shivering control is limited by the potential for extrapyramidal side effects and tardive dyskinesia.

**Core Concept:** Post-operative shivering is typically treated to prevent heat loss, prevent electrolyte imbalances, and improve patient comfort. The correct drugs target the hypothalamic thermoregulatory center, reducing shivering through dopamine antagonism.

**Clinical Pearl:** In cases where dopamine antagonists are contraindicated or not effective, antipsychotics like levomepromazine and haloperidol can be considered for controlling post-operative shivering due to their action on the hypothalamic thermoregulatory center. However, these medications should be used with caution, given their potential side effects.