Pharmacology

Pharmacokinetics and pharmacodynamics are two key areas of study within pharmacology about which health professionals should have a basic knowledge.

Video: Pharmacokinetics

6:10

Pharmacokinetics is concerned with how the body interacts with a substance (such as how the substance is absorbed, metabolized, and excreted). Health professionals should be aware of how psychedelic medicines work their way through the body in order to understand the duration of the medicine’s effects and when they can be expected to wear off. In this video, public health nurse Cathy Parkes talks about the five main phases of pharmacokinetics.

Video: Pharmacodynamics

4:56

Pharmacodynamics is concerned with how a substance interacts with the body (such as what response or effects does the substance trigger in the mind and body). This area of study is key for health professionals to understand how the psychedelic medicine is effecting the body as well as aligning desired effects with the appropriate dose. In this video, we will look at some foundational aspects about pharmacodynamics and the bioavailability and concentration of a substance in the body required for a specific effect.

Traditional Mental Health Pharmacotherapy

Depression is one of the most common psychiatric disorders that is usually chronic or recurrent in nature (Solomon et al., 2000). Recurrent episodes of depression can be triggered by early discontinuation of antidepressant therapy or psychotherapy alongside a failure to respond to antidepressant medication (Fava, 2003).

It is estimated that up to 50-60% of patients do not achieve adequate response (i.e., remission) following antidepressant treatment (Fava et al., 2003).

For those who do not achieve remission after the first treatment, there is usually a 30% remission rate after the second medication (Gaynes et al., 2019; Fava et al., 2003).

After the third treatment, the remission rate is about 25-35% (Fava et al., 2003).

Failure to achieve remission is relatively common and is frequently referred to as treatment-resistant depression (Gaynes et al., 2019; Fava, 2003).

Did You Know?

One of the reasons behind the low adherence and remission rates after standard pharmacotherapies is related to how these antidepressants work. Typical antidepressants relieve depression symptoms by increasing the bioavailability of certain neurotransmitters–usually some combination of serotonin, dopamine, and norepinephrine (Harmer et al., 2017). In contrast, psychedelic-assisted therapy is intended to assist clients in coping with their repressed emotions and promote healing.

Adverse Effects

Finally, a brief note on the difference between effects and adverse effects as used throughout the course. Effects are expected, intended, and desired, meaning they are the primary reasons for consuming the medicine. On the other hand, adverse effects are reactions to a medication that are usually undesired (CDC, 2021).

References

Centre for Disease Control (2021). Understanding Adverse Events and Adverse effects. https://www.cdc.gov/vaccinesafety/ensuringsafety/sideeffects/index.html

Fava, M. (2003). Diagnosis and definition of treatment-resistant depression. Biol Psychiatry, 53(8), 649- 659. https://doi.org/10.1016/s0006-3223(03)00231-2

Fava, M., Rush, A. J., Trivedi, M. H., Nierenberg, A. A., Thase, M. E., Sackeim, H. A., . . . Kupfer, D. J. (2003). Background and rationale for the sequenced treatment alternatives to relieve depression (STAR*D) study. Psychiatr Clin North Am, 26(2), 457-494. https://doi.org/10.1016/s0193- 953x(02)00107-7

Gaynes, B. N., Lux, L., Gartlehner, G., Asher, G., Forman-Hoffman, V., Green, J., Boland, E., Weber, R. P., Randolph, C., Bann, C., Coker-Schwimmer, E., Viswanathan, & M., Lohr, K. N. (2019). Defining treatment resistant depression. Depression Anxiety, 37, 134-145. https://doi.org/10.1002/da.22968

Harmer, C. J., Duman, R. S., & Cowen, P. J. (2017). How do antidepressants work? New perspectives for refining future treatment approaches. Lancet Psychiatry, 4(5), 409-418. https://doi.org/10.1016/s2215-0366(17)30015-9

Solomon, D. A., Keller, M. B., Leon, A. C., Mueller, T. I., Lavori, P. W., Shea, M. T., . . . Endicott, J. (2000). Multiple recurrences of major depressive disorder. Am J Psychiatry, 15(7), 229-233. https://doi.org/10.1176/appi.ajp.157.2.229