Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1 Pharmacodynamic properties
Paracetamol is a peripherally acting analgesic with antipyretic activity.
Codeine is a centrally acting weak analgesic. Codeine exerts its effect through µ opioid receptors, although codeine has low affinity for these receptors, and its analgesic effect is due to its conversion to morphine.
Codeine, particularly in combination with other analgesics such as paracetamol, has been shown to be effective in acute nociceptive pain.
Atropine:
Atropine is an antimuscarinic agent. These substances are competitive inhibitors of acetylcholine at muscarinic receptors of autonomic effector sites with parasympathetic innervation.

Pharmacokinetic Properties

5.2 Pharmacokinetic properties
Paracetamol & Codeine:
Paracetamol is readily absorbed from the gastrointestinal tract with peak plasma concentrations occurring about 30 minutes to 2 hours after ingestion.
Paracetamol is metabolised in the liver and excreted in the urine mainly as the glucuronide and sulphate conjugates, with about 10% as glutathione conjugates. Less than 5% is excreted as unchanged paracetamol.
The elimination half life varies from about 1-4 hours. Plasma protein binding is negligible at usual therapeutic concentrations, although this is dose dependent.
Codeine phosphate is absorbed from the gastrointestinal tract and peak plasma concentrations occur after about one hour.
Codeine is metabolised by O- and N-Demethylation in the liver to morphine and norcodeine. Codeine and its metabolites are excreted almost entirely by the kidney, mainly as conjugates with glucuronic acid.
The plasma half life has been reported to be between 3 and 4 hours.
Atropine:
Atropine is readily absorbed from the gastro-intestinal tract and mucous membranes.
It is rapidly cleared from the blood and is distributed through the body, crossing the blood-brain barrier. It is completely metabolised in the liver and is excreted in the urine as unchanged drug and metabolites.