Phenazopyridine-Mechanism of action

Mechanism of action of Phenazopyridine:-  

It is a competitive inhibitor of dihydrofolate synthase. It is required for  synthesis of folic acid and it is an essential component for bacterial growth. The multiplication of bacteria is therefore inhibited by the action of phenazopyridine.

Pentobarbital- Mechanism of action

Mechanism of action of Pentobarbital:-  

Pentobarbital binds at a distinct binding site associated with a Cl- ionopore at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged. All of these effects are associated with marked decreases in GABA-sensitive neuronal calcium conductance (gCa). The net result of barbiturate action is acute potentiation of inhibitory GABAergic tone. Barbiturates also act through potent (if less well characterized) and direct inhibition of excitatory AMPA-type glutamate receptors, resulting in a profound suppression of glutamatergic neurotransmission.

Pentazocine-Mechanism of action

Mechanism of action:- 

  Pentazocine is a potent analgesic which when administered orally in a 50 mg dose appears equivalent in analgesic effect to 60 mg (1 grain) of codeine. The evidence suggests that pentazocine antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor.

Sulfasalazine-Mechanism of action

Mechanism of action:-
The mode of action of Sulfasalazine or its metabolites, 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP), is still under investigation, but may be related to the anti-inflammatory and/or immunomodulatory properties that have been observed in animal and in vitro models, to its affinity for connective tissue, and/or to the relatively high concentration it reaches in serous fluids, the liver and intestinal walls, as demonstrated in autoradiographic studies in animals. In ulcerative colitis, clinical studies utilizing rectal administration of Sulfasalazine, SP and 5-ASA have indicated that the major therapeutic action may reside in the 5-ASA moiety. The relative contribution of the parent drug and the major metabolites in rheumatoid arthritis is unknown.

Sulfacetamide- Mechanism of action

Mechanism of action of Sulfacetamide: -

It is a competitive inhibitor of bacterial para-aminobenzoic acid (PABA). PABA is required for bacterial synthesis of folic acid and it is an essential component for bacterial growth. The multiplication of bacteria is therefore inhibited by the action of sulfacetamide.

Penfluridol- mechanism of action

Mechanism of action of penfluridol: - 

Penfluridol binds to the dopamine receptor (D1, D2, D3 &D4).It exerts its antipsychotic activity by blocking the dopamine projections in the limbic system and in mesocortical area. Peripherally and centrally it acts as a competitive Dopamine antagonist.

Reference:-
Tripathi k.d.,"Essentials of Pharmacology",published by jaypee brother publication ,new dehli,seventh edition,p.no:-441

Pantoprazole - Mechanism of action

Mechanism of action of pantoprazole: -

Pantoprazole is a proton pump inhibitor (PPI) that suppresses the final step in gastric acid production by forming a covalent bond to two sites of the (H+,K+ )- ATPase enzyme system at the secretory surface of the gastric parietal cell. This effect is dose- related and leads to inhibition of both basal and stimulated gastric acid secretion irrespective of the stimulus.