Antidepressants and Mood Stabilizers - Craviso Flashcards
Currently available drugs are based on which hypothesis of depression?
The monoamine hypothesis.
Describe the therapeutic strategy and down sides of currently available drugs used to treat depression.
- alleviate depression by affecting monoamine systems
- all cause immediate effects on synaptic monoamine levels
- there is a delay of one or more weeks for symptoms of depression to be alleviated due to later affects
- no one class is superior to the others in treating depression
- at least 20% of all depressed patients are refractory to multiple different antidepressants at adequate doses
Why is there a delay of one or more weeks in relieving symptoms of depression using currently available drugs?
Late effects of these drugs cause a delay due to a slow increase in expression of BDNF that promotes synaptogenesis.
What are the major classes of antidepressant drugs?
- SSRI’s - actions confined to blocking 5HT reuptake
- Serotonin-NE reuptake inhibitors - newer inhibitors selectively block NE and 5-HT reuptake, older inhibitors called tricyclics exert antagonist effects on a variety of receptors (cause more adverse effects)
- New antidepressants - work by various mechanisms including inhibition of dopamine reuptake and agonist/antagonist activities at certain types of 5-HT and NE receptors
- Monoamine oxidase inhibitors - inhibit the metabolism of NE and 5-HT
What are the first line drugs for treating depression?
- SSRI’s
2. selective serotonin-NE reuptake inhibitors - Venlafaxine
In general antidepressant drug actions include what?
- blockage of reupake of serotonin or NE at the nerve terminal
- blockage of metabolism of 5-HT and NE in the nerve terminal
- affect 5HT and NE receptors at the post -synaptic membrane
List the SSRI’s.
- Fluoxetine - prozac, prozac weekly
- Sertraline - zoloft
- Paroxetine - Paxil
- Citalopram - Lexapro
SSRI’s are selective serotonin reuptake inhibitors
What are some important pharmacokinetic considerations when using SSRI’s?
- metabolism occurs in the liver by cytochrome P-450 enzymes
- these drugs may be potent inhibitors of several cytochrome P-450 enzymes - especially CYP2D6
- if CYP2D6 is blocked then the drugs it normally metabolizes could build up and cause adverse effects
Which 2 SSRI’s have a high potential for inhibiting CYP2D6 and other cytochrome P450’s?
Fluoxetine and paroxetine.
Which 2 SSRI’s have a low potential for inhibiting CYP2D6 and other cytochrome P450’s?
Citalopram and escitalopram.
What are the adverse side effects of SSRI’s?
- significant sexual dysfunction such as anorgasmia, ejaculatory delay, impotence and decreased libido
- GI disturbances such as nausea, diarrhea, cramping, heartburn
- insomnia, restlessness
- significant anorexia and weight loss early and significant weight gain long term
- QT prolongation with Citalopram
Describe some other concerns with the use of SSRI’s.
- cause a withdrawal syndrome after long-term use is abruptly stopped - includes nausea, dizziness, anxiety, tremor and palpitations
- use of paroxetine during pregnancy is linked to an increased risk of cardiovascular malformations in the baby
- 5HT syndrome, primarily when used with MAO inhibitors or other drugs that enhance 5HT neurotransmission
What antidepressants can be used for children and adolescents?
Use is limited due to concerns of worsening their depression and suicide.
- Fluoxetine - only SSRI approved for use in children and adolescents
- approved for use in adolescents
Describe some other uses for antidepressants.
- treatment of several types of anxiety disorders
- paroxetine is used to treat seasonal affective disorder
- fluoxetine is used as a migraine prophylactic
- most antidepressants can be used to treat PMS and PMDD
- paroxetine can be used to treat hot flashes
What is Venlafaxine?
A newer, selective serotonin-NE reuptake inhibitor (SRNI). It blocks reuptake of both serotonin and NE and weakly inhibits dopamine reuptake.
What are the adverse side effects of the SNRI’s?
- sexual dysfunction like SSRI’s
- restelessness, insomnia
- GI disturbances like SSRI’s
- dose-related increase in blood pressure
What are the additional uses of SNRI’s
- used to treat anxiety disorders
2. treatment of neuropathic pain
What is Desvenlafaxine (pristiq)?
A metabolite of Venlafaxine
What is Duloxetine (cymbalta)?
- an SNRI
- contraindicated for those with chronic liver disease or hepatic insufficiency
- can be used to treat fibromyalgia, management of diabetic peripheral neuropathy, long term treatment of generalized anxiety disorder
What are Tricyclic Antidepressants?
- SNRI’s
- different TCA’s block both NE and 5HT to varying degrees
- formerly first line drugs to treat depression
List the different TCA’s and to what degree they block uptake of NE and 5HT.
- Nortriptyline (aventyl, pamelor) - blocks NE more than 5HT
- Imipramine (Tofranil) - blocks 5HT more than NE
- Amitriptyline (elavil) - blocks 5HT more than NE
Why are TCA’s not first line drugs anymore?
- can be fatal in overdose
- are cardiotoxic
- have a propensity to lower seizure threshold
- have significant antagonist activity at several types of neurotransmitter receptors - mAch, alpha1, Histamine
Nortriptyline blocks other neurotransmitter receptors - which ones and to what degree?
It blocks mAch, alpha1 and histamine receptors - all to the same degree.