Question

What is each drug's classification, and what is each drug's mechanism of action (how does it work as an antiemetic)? List expected dosage range for this patient and any patient factors that would affect dosing. List the advantages and disadvantages of each medication for this patient-this will include onset, side effects/precautions and CIs. Discuss monitoring with each of these medications. prochlorperazine

Answer 1

Ans) Prochlorperazine:

Drug classification: Dopamine receptor antagonist that belongs to the phenothiazine class of antipsychotic agents.

Mechanism of action: The mechanism of action of prochlorperazine has not been fully determined, but may be primarily related to its antidopaminergic effects.

- Blocks the D2 somatodendritic autoreceptor, resulting in the blockade of postsynaptic dopamine receptors in the mesolimbic system and an increased dopamine turnover.

-Also it has anti-emetic effects, which can be attributed to dopamine blockade in the chemoreceptor trigger zone.

- Prochlorperazine also blocks anticholinergic and alpha-adrenergic receptors, the blockade of alpha(1)-adrenergic receptors resulting in sedation, muscle relaxation, and hypotension.

Expected dosage:

Prochlorperazine in suppository form comes in 25 milligram (mg) doses that can be taken twice a day. Tablets come in 5 and 10 mg formulas with a recommended dose of 10 to 40 mg a day.

Side effects:

• Drowsiness
• Difficulty falling or staying asleep
• Dizziness
• Increased appetite, weight gain
• Dry mouth
• Blurred vision
• Decreased sexual ability in men
• Fever
• Confusion
• Fast, irregular heartbeat
• Stiffness in muscles
• Sweating
• Breathing or swallowing problems
• Rash, hives, itching, swelling of eyes, face or other parts
• Yellow skin, eyes
• Erection lasting for hours

Promethazine:

Drug classification: Phenothiazine derivative with primarily antihistaminic effects and also has antiemetic, anticholinergic, sedative actions.

Mechanism of action:

- Promethazine blocks the binding of histamine to receptors this prevents the actions of histamine.

- It blocks histamine receptors in an area of the brain called the vomiting center. It also acts to block other receptors in the vomiting center (serotonin receptors).

Dosage:

Treatment: 12.5 to 25 mg IM, IV, orally, or rectally every 4 hours as needed

Prophylaxis:
-Oral and Rectal: 25 mg orally every 4 to 6 hours as needed

Side effects:

• Convulsions (seizures)
• difficult or unusually fast breathing
• fast heartbeat or irregular pulse
• high fever
• high or low (irregular) blood pressure
• increased sweating
• loss of bladder control
• severe muscle stiffness
• unusually pale skin
• unusual tiredness or weakness

Precautions to both the above drugs i.e prochlorpromazine and promethazine is to inform Doctor about history of any signs & symptoms, allergy, etc.

- If dose is skipped then do tell doctor

- Report any signs & symptoms of complication.