Module 8: Unit B Thyroid, T, ED, BPH Flashcards
Indication for levothyroxine (T4) (Synthroid)
hypothyroidism (all forms)
MOA levothyroxine
Synthetic T4 is converted to active T3
D2D Levothyroxine
Absorption is reduced by food, antacids, multivitamins, chelating agents, H2B, PPI, Fe, Mg. Some medications like phenytoin, rifampin, sertraline, and carbamazepine can increase the metabolism of levothyroxine.
Levothyroxine ↑ effects of warfarin and ↑ cardiac sensitivity to catecholamines
What can OD of levothyroxine cause?
Thyrotoxicosis: tachycardia, tremor, nervousness, angina, insomnia, hyperthermia, heat intolerance, and sweating.
What can overuse of levothyroxine cause?
Chronic overuse can accelerate bone loss and ↑ risk of AFIB
BBW levothyroxine
should not be used for the treatment of obesity or for weight loss.
Pt teaching and monitoring with levothyroxine
Levothyroxine should be given in the morning, by itself, with water and at least 30 (preferably 60) minutes before meals.
Long half-life (7 days). Check TSH 6-8 weeks after initiating med or changing dose. (Consider checking T4 if TSH remains high).
Maintain patient on the same brand when possible; if a change is necessary, check TSH and/or T4 in 6-8 weeks
T replacement examples
topical testosterone gels, solutions, and patches (Androgel, Adroderm, Axiron)
Nasal testosterone gel (Natesto)
Parenteral testosterone:
T. cypionate (Depo-testosterone)
T. enthanthate (Delatestyrl)
Indications for testosterone therapy
Male hypogonadism (<300)
Replacement therapy
Delayed puberty
Cachexia (wasting syndrome)
Safety with T
Causes virilization in women, girls, and young boys (coarse body hair, deepening voice, clitoral/penile enlargement, increased libido).
Premature epiphyseal closure.
Hepatotoxicity.
↑ LDL, ↓ HDL
Accelerates prostate CA (after it occurs; not causative but proliferative)
Edema from retention of Na and H20
↑ risk of thromboembolic events (↑ H&H = hypercoagulable state)
ABUSE POTENTIAL
Rash-patches
Topicals can be transferred to others by skin-to-skin contact
BBWs testosterone
Blood pressure increases (oral testosterone undecanoate; subQ testosterone enanthate)
Secondary exposure (transdermal gel, transdermal solution):
Pulmonary oil microembolism (intramuscular testosterone undecanoate):
What schedule is testosterone?
Scheulde III
Monitoring with testosterone
Measure testosterone 2-3 weeks after initiating treatment and then every 3-6 months. Include CBC, CBP, and lipid profile at least every six months
Examples of PDE 5 inhibitors
-NAFIL
sildenafil (Viagra)
tadalafil (Cialis)
vardenafil (Levitra)
avanafil (Stendra)
Uses for: sildenafil (Viagra)
tadalafil (Cialis)
vardenafil (Levitra)
avanafil (Stendra)
Erectile dysfunction
MOA PDE-5 Inhibitors (Viagria, etc.)
Selective inhibition of PDE-5 leading to ↑ cGMP in the penis, causing local artery dilation, ↓ venous outflow, and subsequent engorgement of the corpus cavernosum.
Safety and D2D with PDE-5 Inhibitors
Hypersensitivity
Concurrent use (regularly/intermittently) of organic nitrates in any form (e.g., nitroglycerin, isosorbide dinitrate);
concomitant use of riociguat (Adempas)(a guanylate cyclase stimulator)
Side effects PDE-5 Inhibitors
Hypotension, priapism, nonarteritic ischemic optic neuropathy, sudden hearing loss, HA, visual changes, flushing, dyspepsia.
May exacerbate OSA
D2D PDE5-I
CYP3A4 inhibitors can ↑ levels (grapefruit, erythromycin, ketoazonole)
alpha-adrenergic blockers with PDE-5 inhibitors can lower BP and cause postural hypotension
NO NITRATES
Considerations/counseling with PDE-5-I
Consider de-prescribing or changing medications known to cause sexual/erectile dysfunction: SSRIs (fluoxetine and paroxetine), mood stabilizers, TCAs, MAOIs, spironolactone, HCTZ, beta-blockers, clonidine, digoxin, and finasteride. Also, advise avoiding alcohol.
Counsel patients with CVD to NOT use PDE-5s with hypotension (<90/50 mm Hg); uncontrolled hypertension (>170/110 mm Hg); recent arrhythmias, stroke or MI (< six months), history of CAD with unstable angina; aortic stenosis,
5-𝝰-reductase inhibitors
-ASTERIDE
finasteride (Proscar)
dutasteride (Avodart)
Indications for:
finasteride (Proscar)
dutasteride (Avodart)
BPH
(generally best when treating men with large prostates and mechanical obstruction)
MOA
finasteride (Proscar)
dutasteride (Avodart)
Reduces the size of the prostate (over time) by inhibiting 5-𝝰-reductase, which ↓ conversion of testosterone to dihydrotestosterone (DHT). As DHT ↓, prostate tissue shrinks (over 6-12 months)
dutasteride MOA is similar but has more complete inhibition 5-𝝰-reductase and has a long half-life of 5 week
Safety considerations for finasteride (Proscar) and dutasteride (Avodart)
Teratogenic, pregnant women should not handle medication.
Patients should not donate blood while taking medication (and up to 6 months after stopping)
Can ↓ libido and ejaculate volume.
Gynecomastia
NOT intended to prevent cancer
Monitoring with finasteride (Proscar) and dutasteride (Avodart)
Causes PSA to ↓; Repeat the PSA at six months. If PSA does not decrease, investigate for prostate CA
Examples of 𝛼1-adrenergic antagonists
-SIN
tamsulosin (Flomax)
silodosin (Rapaflo)
doxazosin (Cardura)
terazosin (Hytrin)
alfuzosin (Uroxatral)
indication:
tamsulosin (Flomax)
silodosin (Rapaflo)
doxazosin (Cardura)
terazosin (Hytrin)
alfuzosin (Uroxatral)
BPH
(generally best for treating men with smaller prostates and dynamic obstruction
MOA
tamsulosin (Flomax)
silodosin (Rapaflo)
doxazosin (Cardura)
terazosin (Hytrin)
alfuzosin (Uroxatral)
𝛼1-adrenergic receptor blockade causes smooth muscle relaxation in the bladder neck, prostate capsule, & prostatic urethra, which ↑ urinary flow. Does NOT reduce prostate size.
Safety/D2D with:
tamsulosin (Flomax)
silodosin (Rapaflo)
doxazosin (Cardura)
terazosin (Hytrin)
alfuzosin (Uroxatral)
nonselective agents (doxazosin, terazosin, alfuzosin) can ↓BP and cause dizziness, fainting, somnolence, and nasal congestion.
Use cautiously with antihypertensive medications, nitrates, PDE-5
tamsulosin and silodosin can cause abnormal ejaculation (failure, retrograde, reduced volume)
Does NOT lower PSA
CYP3A4 inhibitors can ↑levels of silodosin and alfuzosin
