Group: opioid analgesics
Indications: moderate to severe pain, obstetric analgesia; peri-operative analgesia
Mechanism: Intereacts with opioid receptors. Pethidine has effects similar to morphine, but has very little effect on cough or diarrhoea. Pethidine is more lipid-soluble than morphine resulting in a faster onset of action. Its duration of clinical effect is 120-150 minutes. In addition, it has a slight antimuscarinic effect.
Amitriptyline Hydrochloride by L. Heath
Group: Tricyclic antidepressants (TCA)
Depressive illness, particularly where sedation is required
Nocturnal enuresis in children – not first line treatment
Mechanism of Action:
TCA’s work by blocking serotonin (5HT) and noradrenaline (NA) re-uptake into the presynaptic terminal from the synaptic cleft.
The amine hypothesis states that depression results from a depletion of monoamine neurotransmitters (such as 5HT and NA). Amitriptyline by blocking the re-uptake of 5HT / NA increases their availability to the post-synaptic membrane.
As it is a sedating drug it should be taken at night to help with sleep.
GABApentin by Louise Waring
GABA is an inhibitory neurotransmitter used at roughly one-third of the synapses in the brain. The binding of GABA at the GABA recognition site causes the membrane-spanning channel of the receptor protein to open and allow an influx of negatively charged chloride ions. This influx of negative ions serves to hyperpolarize the cell thus inhibiting the firing of an action potential.