There are many aspects that affect the pharmacokinetics and pharmacodynamics of medicines. Simmons (2020) distinguishes internal and external factors between the factors influencing patients’ pharmacokinetics and pharmacodynamic processes. The external ones include the ambient temperature, the solubility of drugs, their isomerism and polarity, as well as the intake of medicines into the body, including the dosage form, the method and duration of administration, the dose, and the combination of drugs. In turn, internal factors include gender, age, genotype and phenotype of the patient, as well as his physiological aspects and pathologies, including nutrition, pregnancy, lactation, stress, comorbidities, alcoholism, and smoking. Thus, the pharmacodynamics and pharmacokinetics of drugs depend on all these aspects.
In this case, it is vital that the patient has hypertension, so Lithium should be taken with caution. Moreover, patients with diabetes mellitus should be given a specific dosage of the drug. Fazio et al. (2017) assert that elderly and debilitated patients require adjustment of the Lithium dosing regimen. Since, in this case, the patient is 68 years old, his age should also be taken into account when prescribing a specific dose of the drug.
Moreover, it is essential to pay attention to drug interactions. According to Pilmark et al. (2021), with the simultaneous use of Metformin with Lithium preparations, glycemic control decreases. In turn, when taking Hydrochlorothiazide with Lithium, it is possible to increase lithium concentration in the blood to a toxic level. An equally important factor is the compatibility of the drug with alcohol. Finley (2016) notes that alcohol is not allowed during Lithium treatment. Moreover, alcohol consumption during Metformin treatment increases plasma lactic acid concentrations and increases the risk of hypoglycemia. Thus, this aspect is also a factor influencing the pharmacokinetic and pharmacodynamic processes of the patient.
The individualized treatment plan may change significantly if the patient has a concomitant medical condition such as renal failure, heart failure, or liver failure. The presence of such diseases affects the reception of Lantus. Krentz et al. (2019) affirm that in patients with severe liver failure, the need for insulin can be reduced due to a decrease in the ability to gluconeogenesis and a slowdown in insulin biotransformation. Moreover, in patients with impaired renal function, the need for insulin may decrease due to the weakening of its elimination processes. In elderly patients, progressive deterioration of renal function can lead to a persistent decrease in insulin requirements.
References
Fazio, P., Gaetano, R., Caroleo, M., Pavia, M., De Sarro,G., Fagiolini, A. & Segura-Garcia, C. (2017). Lithium in late-life mania: A systematic review. Neuropsychiatric Disease and Treatment, 13, 755-766.
Finley, P. (2016). Drug interactions with Lithium: An update. Clinical Pharmacokinetics, 55(8), 925-41.
Krentz A., Weyer C., & Hompesch M. (2019). Translational research methods in diabetes, obesity, and nonalcoholic fatty liver disease. Springer.
Pilmark, N.S., Lyngbæk, M., Oberholzer, L., Elkjær, I., Petersen-Bonding, C., Kofoed, K., Siebenmann, C., Kellenberger, K., Hall, G., Abildgaard, J., Ellingsgaard, H., Lauridsen, C., Ried-Larsen, M., Pedersen, B., Hansen, K. & Karstof, K. (2021). The interaction between Metformin and physical activity on postprandial glucose and glucose kinetics: A randomised, clinical trial. Diabetologia, 64, 397–409.
Simmons, M. (2020). Pharmacology: An essential textbook. (2nd ed.). Thieme.