The activity of receptors in the human body depends on their type and the specificity of their functions. Receptors are located in the membranes of the cells and directly interact with ligands, bind with them, and stimulate the immune system responses. When the receptors bind with drugs, they respond in various ways. The differences between the four main actions a drug can have after binding to a receptor are conditioned by whether a ligand is an agonist, partial agonist, antagonist, or inverse agonist.
Firstly, agonists bind with receptors and trigger a direct response in the receptor using conformational change. The biological effect is achieved by the higher concentration of ligands that lead to an increased number of affected receptors. An example of medications in this category might be codeine or isoproterenol, which reproduces the effect of adrenaline (Burchum & Rosenthal, 2018). Secondly, on the contrary to agonists, antagonists occupy the receptors and block their ability to respond to other agonists (Rao & Andrade, 2016). Naloxone, a medication that blocks opioids’ effects on receptors, is an example of psychiatric drugs from the category of antagonists. Thirdly, partial agonists bind with the receptors but cannot achieve their full biological response. Their mediated activity is important when it is necessary to reduce the scope of adverse effects of the medications. An example of the medications from this category might be buprenorphine (Burchum & Rosenthal, 2018). Finally, inverse agonists have an effect that completely opposite to that of agonists by preventing receptor activity. Its key difference from antagonists is that it does not need agonists to influence the receptor; pimavanserin (nuplazid) is an inverse agonist medication example.
A G-protein-linked receptor is a membrane protein, which is a constituent of the biggest receptor family. It triggers the physiological processes in the body by transmitting the extracellular information and triggering responses in the cells (Burchum & Rosenthal, 2018). An ion channel is the type of receptors that “regulate flow of ions into and out of cells” (Burchum & Rosenthal, 2018, p. 47). When an agonist of ligand binds the receptor, the ion channel opens and allows for ions to be transmitted. Neurotransmitters like acetylcholine function by means of ion channels. The main difference between ion channels and G-protein linked receptors is that the first open a channel for ions, and the latter activates G-protein for further functioning. Morphine is the medication that acts on a G-protein receptor, and lidocaine is an example of a medication that acts on ion channels.
The interconnection between drugs and receptors is pivotal for the pharmacological sphere. According to Berg and Clarke (2018), the particularities of drugs to trigger specific responses in receptors predetermine the bodily responses to the medications and should be used as the ground for psychiatric treatment. Therefore, the chemical basis and contents of the medications used for particular disorders influence the ways a therapist prescribes medications. An exemplar case of the importance of the drug’s action at the receptor when it is critical for a patient’s safety might include the prescription of anti-anxiety medications. Indeed, if the patient with chronic conditions that have symptoms of low blood pressure will be prescribed anti-anxiety medication, the overall effect might be dangerous due to the receptor-drug interaction and the side effects of the drug.
References
Berg, K. A., & Clarke, W. P. (2018). Making sense of pharmacology: Inverse agonism and functional selectivity. International Journal of Neuropsychopharmacology, 21(10), 962-977.
Burchum, J., & Rosenthal, L. (2018). Lehne’s pharmacology for nursing care. Amsterdam, UK: Elsevier Health Sciences.
Rao, T. S., & Andrade, C. (2016). Classification of psychotropic drugs: Problems, solutions, and more problems. Indian Journal of Psychiatry, 58(2), 111-113.