Meds Flashcards
What is drug class and mechanism of action of frusemide?
- loop diuretic
- inhibits Na+/K+/2Cl cotransporter
What is frusemide used for?
Oedema - pulmonary or ascites, assoc with cardiac insufficiency/CHF and acute, non-inflam tissue oedema
- hypercalcaemia
- Systemic hypertension
- Oliguric AKI
- prevention of sterile haemorrhagic cystitis secondary cyclophosphamide
What is drug class and mechanism of action of frusemide?
- loop diuretic
- inhibits Na+/K+/2Cl cotransporter
What is torsemide used for?
- CHF management
What is drug class and mechanism of action of sildenafil?
Vasodilator and phosphodiesterase 5 inhibitor
inhibits cGMP specific PD5 => NO mediated vasodilation within the pulmonary vascular smooth muscle
What is sildenafil used for?
- reduce pulmonary hypertension with primary cardiac, respiratory or HW
- slow cardiac remodeling with MMVD
- congenital MO
- Eisenmengers syndrome
What is drug class and mechanism of action of Spironolactone?
Aldosterone antagonist - potassium sparing diuretic
Aldosterone is competitively inhibited by spironolactone in the distal renal tubules with resultant increased excretion of sodium, chloride, and water, and decreased excretion of potassium, ammonium, phosphate, and titratable acid.
What is spironolactone used for?
- CHF for cardioprotective and potassium sparing diuretic
- ascites
What is drug class and mechanism of action of Hydrochlorothiazide?
Thiazide diuretic
acts on cortical diluting segmen of nephron and interfers with the transport of sodium ions across renal tubular epithelium.
What is hydrochlorothiazide used for?
Nephrogenic diabetes insipidus
- hypertension
- CaOx urolith prevention
- hypoglycaemia
- Diuretic for CHF
- ascites
- Hypermagnesemia
- antihypertensive
What is drug class and mechanism of action of Nitroglycerin?
Venodilator and afterload reducer
relaxes predominantly venous smooth muscle + dose related arteriole effect via formation of NO
What is nitroglycerin used for?
vasodilator in acute CHF
What is drug class and mechanism of action of hydralazine?
Vasodilator - semicarbazide-sensitive amine oxase inhibitor - alters Ca++ metabolism to reduce contraction. more impact on arterioles than veins.
Increase CO and decrease systemic vascular resistance
What is hydralazine used for?
- Afterload reducer for CHF
- Antihypertensive
What is drug class and mechanism of action of Prazosin?
Alpha 1 adrenergic blocker
Selective, competative inhibition of post-synaptic a1-adrenergic receptors. directly relaxes smooth muscle on both arterial and venous
What is prazosin used for?
- Reduce sympathetic tone to treat functional urethral obstruction and idiopathic vesico-urethral reflex dyssynergia or urethral spasm
- dysuria with prostatic carcinoma
- hypertension
- adjunctive treatment of heart failure
What is drug class and mechanism of action of benazepril?
ACE-i
What is benazepril used for?
- CHF
- hypertension
- CKD
- Proteinuria
What is drug class and mechanism of action of Pimobendan?
Inodilator - positive iontrop and vasodilatory effects
Inhibits PDE-III and increases intracellular calcium sensitivity
What is pimobendan used for?
- CHF in dogs secondary to DCM or degen AV valve insuff
- Preclinical (stage B2) MMVD and DCM
- Pulmonary arterial hypertension
- non-obstructive HCM with left ventricular systolic dysfunction and CHF in cats
What is drug class and mechanism of action of Amlodipine?
Calcium channel blocker (L-type)
inhibits volutage gated calcium channels in cardiac and vascular smooth muscle.
kindeys - Ltype are found in the afferent arterialos.
What is Amlodipine used for?
- Systemic arterial hypertension
- afterload reduction in refractory CHF
What is drug class and mechanism of action of Nitroprusside?
Vasodilator - arterial and venous
provides intracellular NO => increased cGMP => inhibits vascular smooth muscle contration.
What is nitroprusside used for?
- acute/severe hypertension inc phaeo
- acute CHF
- dobutamine for refractory CHF
When should nitroprusside not be used?
- compensatory hypertension eg AV shunts, coarctation of the aorta, cushing’s reflex.
- inadequate cerebral circulation or emergency surgery if the patient is near death
- hypoT4 or low sodium
- undiluted
- geriatric, renal , liver.
What is drug class and mechanism of action of Diltazem?
Calcium channel blocker - benzothiazeprines
Class IV antiarrhythmic
weak negative ionotrope
act on nodal cells to prolong refractory period and slow conduction.
What is diltiazem used for?
- SVT (originate above the AV node), Afib
- systemic hypertension
- pulmonary hypertension
When should diltazem not be used?
- hypothension
- sinus node dysfunction
- high grade AV block
- sick sinus syndrome
- pulonary congestion or oedema
- acute myocardial infarction
- old, liver, renal - use with care
What is drug class and mechanism of action of dobutamine?
Beta adrenergic inontrope
direct B1 and mild B2 and alpha 1 adrenergic effects
mild chronotropic, arrhtymogenic and vasodilatory effects. increase cardiac output and work.
What is dobutamine used for?
- shock
- CHF
- hypotension during GA
When should dobutamine not be used?
- subaortic stenosis
- insufficient blood volume
- vent tachyarrhythmia or afib. use digoxin first for afib.
What is drug class and mechanism of action of dopamine?
Adrenergic/dopaminergic ionotrope
acts directly and indirectly on alpha and beta receptors
lower dose = β1 effects, exerting positive cardiac inotropic activity (eg, increased contractility, cardiac output, heart rate);
a CRI of 10 – 15 µg/kg/min IV will have both β1 and α1 effects,3-6 although α1 effects (eg, increased systemic and pulmonary vascular resistance, increased venous return) predominate in a dose-dependent fashion.
what is dopamine used for?
- correct hypotension assoc with low Cardiac output in patient with shock after adequate fluid replacement or peripheral vasodilation
- CHF
- hypotension under GA
When should dopamine not be used?
- phaeo
- V-fib
- uncorrected tachyarrhythmia
- occlusive vascular disease
- oliguric AKI
What is drug class and mechanism of action of digoxin?
Cardiac glycoside
thought to increase the availability of Ca++ to myocardial fibers and inhibit Na+/K+ ATPAse withincrease intracallual Na+ and decreased K+
- increase myocardial contraction (+ve ionotrope)
- decrease conduction velocity through AV node and prolong refractory period.
What is digoxin used for?
- CHF
- Afib or flutter (+diltiazem)
- SVT
When should digoxin not be used?
- Vfib
- digitalis intoxication
- 3rd degree AV block
+/- cats with HCM
- don’t give extravascular
- care with complex arrhythmia and subaortic stenosis.
What is drug class and mechanism of action of mitoxantrone?
Antineoplastic - antitumour antibiotic.
Binds DNA and inhibits both DNA and RNA synthesis via inhibition of RNA and DNA polymeraizses and topoisomerase II
not cell phase specific, but most active in S-phase
What is mitoxantrone used for?
- UCC/TCC and AGASAC
- cardiac sparing/post max dose of doxorubicin
- rescue lymphoma
- mammary/renal adenocarcinoma
- SCC
- thyroid or prostate carcinoma
- fibroid sarcoma
When should mitoxantrone not be used?
- myelosuppression
- infection
What is melphalan used for?
- Multiple myeloma
Which agents are alykylating chemo drugs? and what is their mechanism of action?
Alykylating agents:
- melphalan
- cyclophosphamide
- Chlorambucil
- meclorethamine (mustargen)
- Ifosfamide
covalent binding of alkyl groups to cellular macromolecules = > cross link DNA
What is the drug class and mechanism of action for Cyclophosphamide?
Alykylating agent
covalent binding of alkyl groups to cellular macromolecules = > cross link DNA
What is cyclophosphamide used for?
- Multiagent chemo for lymphoma
- bone marrow abalation prior to BM transplantion
- Sarcoma
- Mammary carcinoma
- metronomic chemo
Which agents are alykylating chemo drugs? and what is their mechanism of action?
Alykylating agents:
- melphalan
- cyclophosphamide
- Chlorambucil
- meclorethamine (mustargen)
- Ifosfamide
- CCNU
- procarbazine
- Dacarbazine (DTIC)
- Streptozocin
covalent binding of alkyl groups to cellular macromolecules = > cross link DNA
What is Ifosfamide used for?
- sarcomas including feline injection site sarcoma
What is the drug class and mechanism of action for chlorambucil?
Alykylating agent + immunosuppressant
covalent binding of alkyl groups to cellular macromolecules = > cross link DNA
What is chlorambucil used for?
- chronic lymphocytic leukaemia
- T-cell lymphoma
- Waldenstrom’s macroglobulinaemia
- Feline low grade/small cell GI lymphoma
- metronomic chemo for bladder TCC
- multiple myeloma
- MCT
- cutaneous plasmacytosis
- Polycythemia vera
- Ovarian adenocarcinoma.
- HSA
- immunosuppression for IBD, IMHA, non-erosive arthritis, immune med skin disease
What is chlorambucil used for?
Round tumours:
- chronic lymphocytic leukaemia
- T-cell lymphoma
- Waldenstrom’s macroglobulinaemia
- Feline low grade/small cell GI lymphoma
- multiple myeloma
- MCT
- cutaneous plasmacytosis
- Polycythemia vera
Other
- metronomic chemo for bladder TCC
- Ovarian adenocarcinoma.
- HSA
- immunosuppression for IBD, IMHA, non-erosive arthritis, immune med skin disease
What is the drug class and mechanism of action for chlorambucil?
Alykylating agent + immunosuppressant
covalent binding of alkyl groups to cellular macromolecules = > cross link DNA
What is the drug class and mechanism of action for Lomustine (CCNU)?
Nitrosourea - alkylating agent
DNA-DNA or DNA to protein cross links.
What is the drug class and mechanism of action for Lomustine (CCNU)?
Nitrosourea - alkylating agent
Cell cycle non-specific
DNA-DNA or DNA to protein cross links.
What is CCNU used for?
- CNS neoplasia
- MCT
- histocytic sarcoma
- rescue lymphoma
metronomic chemo
What is the drug class and mechanism of action for Streptozocin?
Nitrosourea - alkylating agent
cell cycle non-specific
DNA-DNA or DNA to protein cross links.
What is streptozocin used for?
- insulinoma
does have activity against gram +ve and gram -ve but cytotoxicity prevents this from being useful.
What is the drug class and mechanism of action for Dacarbazine?
Alkylating agent
methylates the O6 and N7 positions of guanine, thereby ceasing DNA replication elongation and causing DNA double-strand break
not cell phase specific
What is dacarbazine used for?
- on own or + Dox or CCNU for relapsed lymphoproliferative disease
- With dox +/- vinc for HSA
- STS
- Histiocytic sarcoma
- melanoma
What is the drug class and mechanism of action for Procarbazine?
Alkylating agent
inhibit protein, RNA, and DNA synthesis. Procarbazine is auto-oxidized into hydrogen peroxide, which may also directly damage DNA.
What is procarbazine used for?
in combination therapy for lymphoma +/- relapse:
- MOPP (mechlorethamine, vincristine, procarbazine, prednisone)
- MPP (mechlorethamine, procarbazine, prednisone),
- LOPP (lomustine, vincristine, procarbazine, prednisone),
- BOPP (bendamustine, vincristine, procarbazine, prednisone)
What antitumour antibiotics are there? what is their mechanism of action?
Doxorubicin
Mitoxantrone
Actinomycin D
Bleomycin
DNA intercalation, interfering with topoisomerases, and other mechanisms. These drugs usually exhibit cross-resistance with others in their class and with drugs in some other classes, particularly mitotic inhibitors, and they are substrates for the multidrug resistance (MDR) pump
What is the drug class and mechanism of action for Doxorubicin?
Antitumour antibiotic
Inhibition of DNA synthesis, DNA-dependent RNA synthesis, and protein synthesis by inhibiting DNA and RNA polymerases and impairing topoisomerase II, as well as through generation of free radicals
Doxorubicin alters transcription and replication by intercalating with DNA base pair
What is doxorubicin used for?
- lymphoma
- HSA
- OSA
- histiocytic sarcoma
- feline injection site sarcoma
- mammary carcinoma
- Thryoid carcinoma
- Colonic adenocarcinoma
What adverse effects should be noted with doxorubicin?
- anaphalaxis
- extravasation (cold compress + dexrazonaxane)
- cardiotoxicity with both acute and cumulative exposure => transient arrhythmia and DCM => CHF
- nephrotoxicity in cats.
What is the drug class and mechanism of action for Actinomycin D (Dactinomycin)?
Antitumour antibiotic
Bind DNA => inhibit transcription this inhibiting RNA and protien synthesis
What is Acintomycin D used for?
Mulitagne protocol for dogs with lymphoma/lymphoprolif disease as relapse or dox substitute
- bone and STS
- Carcinomas
- Gram +ve and gram -ve bacteria = some fungi
- some immunosuppressant
- some hypocalcaemic activity.
What is the drug class and mechanism of action for Bleomycin?
Bleomycin has both a DNA binding site and a site that binds to the ferrous form of iron. By serving as an electron acceptor from the ferrous ion to an oxygen atom in the DNA strand, bleomycin cleaves DNA and causes cellular apoptosis.
Resistance to bleomycin can result from reduced cellular uptake of the drug, reduced ability to damage DNA, increased rates of DNA repair by the cell and drug inactivation by the enzyme bleomycin hydrolase
What is Bleomycin used for?
lymphomas, oral squamous cell carcinomas, teratomas, nonfunctional thyroid tumors acanthomatous ameloblastoma
may be used intralesional +/= electrophemealization.
gram-negative and gram-positive bacteria and some fungi; however, its cytotoxicity to eukaryote cells prevents it from being clinically useful as an antimicrobial drug.
What drugs are antimetabolite chemo drugs? what is their mechanism of action?
- Cytosine arabinoside
- Methotrxate
- Gemcitabine
- 5-Fluorouracil
- Rabacfosadine
inhibit the use of cellular metabolities in the course of cell growth and division.
What is the drug class and mechanism of action for Cytosine arabinosine?
Antimetabolite and immunosuppressant.
Competes with deoxycytidine triphosphate to inhibit DNA polymerase, resulting in inhibition of DNA synthesis.
Specific to the S phase of the cell cycle (DNA synthesis) and blocks cell progress from the G1 phase to the S phase.
What is cytosine arabinosine (cytarabine) used for?
rescue lymphoma in DMAC protocol (dexamethasone, melphalan, actinomycin-D, Ara-C)
lymphoreticular neoplasia
leukaemia
CNS lymphoma
MUO
What are the different lymphoma protocols?
- DMAC: dexamethasone, melphalan, actinomycin-D, Ara-C)
- MOPP: (mechlorethamine, vincristine, procarbazine, prednisone)
- MPP: (mechlorethamine, procarbazine, prednisone),
- LOPP: (lomustine, vincristine, procarbazine, prednisone),
- BOPP: (bendamustine, vincristine, procarbazine, prednisone)
- CHOP: (cyclophosphamide, doxo, vinc, pred)
- COP: (cyclophosphamide, vinc, pred)
What is the drug class and mechanism of action for methotrexate?
Antimetabolite
folate analog that inhibits the enzyme dihydrofolate reductase, thus depleting reduced folate pools required for purine and thymidylate biosyn-thesis
What is methotrexate used for?
rarely used. used to be for lymphoprolif neoplasia in multi agent protocols.
Some immunosuppressant effect but limited.
What is the drug class and mechanism of action for Gemcitabine?
Antimetabolite chemo
inhibition of DNA synthesis through incorperationi into the DNA strand => inhibition of DNA polymerase => new DNA strand termination
S-phase killing cells undergoing DNA synthesis and inhibiting cell progression to GA/S boundary
What is gemcitabine used for?
- radiosensitizer but not well tolerated.
- with piroxicam in TCC
no benefit noted in lymphoma, OSA, mammary carcinoma or hepatocellyar carinoma.
What is the drug class and mechanism of action for 5 Fluorouracil (5-FU)?
Antimetabolite chemo
incorporated into RNA and DNA interfering with synthesis and function.
The 5-FU metabolite FdUMP is an inhibitor of thymidylate synthetase, leading to depletion of thymidine 5′-monophosphate and thymidine 5′-triphosphate. The alterations in thymidine and deoxyuridine phosphate pools caused by thymidylate synthetase inhibition, effects on DNA synthesis and integrity, and effects on RNA synthesis and processing
What is 5-fluorouracil used for?
- organ epithelial cell tumours - hepatic, pancreatic, renal, mammary +
- GIT adenocarcinoma
- AGASAC
- nasal adenocarcionma
- solar induced SCC
- mammary tumours (+ doxo and cyclophosphamide)
* NOT CATS*
What is the drug class and mechanism of action for Rabacosadine?
Antimetabolite chemo
- guanine nucleotide analog
=> potent, chain-terminating inhibitor of the major deoxyribonucleic acid (DNA) polymerases
inhibits proliferation of mitogen-stimulated lymphocytes and lymphoma/leukemia cell lines
Inhibit DNA synthesis => S-phase arrest and apoptosis
What is rabacosadine used for?
single agent for
- cutaneous T- cell,
- relapsed B-cell,
- multiple myeloma
+ dox => multicentric lymphoma (dog)
What are the antimicrotubule agents and how do they work?
Paclitaxel
Docetaxel
Part of the vinc alkaloids
interference with the polymerization or depolymerization of the microtubules that play critical roles in cell function and division
=> chromosome segregation during mitosis, leading to mitotic arrest.
What is the drug class and mechanism of action for Paclitaxel and Docetaxel?
Antimicrotuble agents. part of vinc alkaloids
alteration in microtubule function causes an abnormal organization of spindle microtubules involved in chromosome segregation during mitosis, leading to mitotic arrest.
What are Paclitaxel and Docetaxel used for?
Mammary carcinoma
SCC
What are the vinc alkaloids? what is their mechanism of action?
- vinblastine
- vincristine
- vindesine
- vinorelbine
bind to a distinct site on tubulin and inhibit microtubule assembly. This inhibition of microtubule function leads to a disruption in the mitotic spindle apparatus resulting in metaphase arrest and cytotoxicity.
What is the drug class and mechanism of action for Vinblastine?
Vinc alkaloid - antimicrotubule chemo
bind to a distinct site on tubulin and inhibit microtubule assembly. This inhibition of microtubule function leads to a disruption in the mitotic spindle apparatus resulting in metaphase arrest and cytotoxicity.
What is vinblastine used for?
- lymphoma rescue or instead of vinc if significant GI adverse effects
- Carcinoma
- MCT
- splenic tumours
- UCC/TCC
What is the drug class and mechanism of action for Vincristine?
Vinc alkaloid - antimicrotubule chemo
bind to b- tubulin and inhibit microtubule assembly. This inhibition of microtubule function leads to a disruption in the mitotic spindle apparatus resulting in metaphase arrest and cytotoxicity.
+ amino acid metabolism interference => purine synthesis CAC and urea formation
What is vincristine used for?
lymphoma/haematopoietic neoplasia (CHOP/COP) - however cats had less side effects with vinblastine so may use this instead of vinc for CHOP
HSA
- transmissible veneral tumours.
some immuno suppressant activity + induces thrombocytosis => IMT
What is the drug class and mechanism of action for Vinrelbine?
Vinc alkaloid - antimicrotubule chemo
bind to b- tubulin and inhibit microtubule assembly. This inhibition of microtubule function leads to a disruption in the mitotic spindle apparatus resulting in metaphase arrest and cytotoxicity.
+ amino acid metabolism interference => purine synthesis CAC and urea formation
What is vinrelbine used for?
- bronchoalveolar or primary pulmonary carcinoma
- histiocytic sarcoma
- MCT
- palliative rescue for TCC
What are the platinum chemo drugs? what is their mechanism of action?
Carboplatin
Cisplatin (not in cats)
Covalent binding of DNA through displacement reaction resulting in bifunctional lesion and inter or intrastrand crosslinks.
What is carboplatin used for?
Sarcomas:
- OSA
melanoma
Carcinomas:
- SCC
- AGASAC
- intestinal
- prostatic
- mesothelioma
- carcinomatosis
- pulmonary
- nasal
- ovarian
Radiation sensitization.
What is cisplatin used for?
NOT CATS
generally use carbo instead as less side effects.
OSA SCC TCC ovarian cacinoma nasal carcinoma Thyroid adenocarcinoma
intracavitary for neoplastic pulmonray effusion
clsplatin impregnated beads for intralesional treatment
with electrochemotherapy for MCT, sarcomas and injection site sarcoma in cats (injected into margins not given systemically).
What is the mechanism of action of cisplatin?
intra- and interstrand DNA cross-linking that causes single- and double-stranded DNA breakage, impairs DNA replication, RNA transcription and protein synthesis, leading to cell death and inhibition of tumor growth
What is the drug class and mechanism of action for hydroxyurea?
Antineoplastic
interfere with DNA synthesis without interfering with RNA or protein synthesis
S phase inhibitor and nay arrest cekks at G1-S border
What is hydroxyurea used for?
- bone marrow disorders:
- polycythaemia vera
- granulocytic leukaemia
- MCT
- meningioma
What is the drug class and mechanism of action for L-asparaginase?
anti-neoplastic
depletion of circulating l-asparagine leads to inhibition of protein synthesis in tumor cells lacking l-asparagine synthetase, causing induction of apoptosis
most effective in the post mitotic G1 cell phase.
What is L-asparaginase used for?
initial induction or at relapse of lymphoprolif disorders. develops resistance.
Which are the tyrosine kinase inhibitors and what is their mechanism of action?
Toceranib
mastinib
imatinib mesylate
small-molecule inhibitors that block, receptor tyrosine kinases (RTKs) expressed on the cell surface by acting as competitive inhibitors of adenosine triphosphate (ATP) binding
+ anti-angiogenic effect through inhibition of VEGFR and PDGFR
+ KIt (Stem cell growth factor)
induce cell cycle arrest and apoptosis in canine tumor cell lines expressing activating mutations in KIT.
What is toceranib used for?
Patniak grade II or III, recurrent cutaneous MCT +- regional LN mets.
- heart base tumours sarcoma - carcinoma - melaonma - multidrug resistant lymphoma - multiple mylepma
What is the drug class and mechanism of action of prednisolone?
Class - glucocorticoid.
induce killing of hematopoietic cancer cells through interaction with the glucocorticoid receptor328 and the induction of apoptosis.3
What is pred used for?
1) replacement or supplementation (eg, relative adrenal insufficiency associated with septic shock) for glucocorticoid deficiency secondary to hypoadrenocorticism,
2) anti-inflammatory agent,
3) immunosuppression,
4) antineoplastic agent
What are the effects of pred?
Cardiovascular system:
- reduce capillary permeability and enhance vasoconstriction, increased blood volume=>increased blood pressure.
Cells: inhibit fibroblast proliferation, macrophage response to migration inhibiting factor, sensitization of lymphocytes, and the cellular response to mediators of inflammation
CNS: lower the seizure threshold, alter mood and behavior, diminish response to pyrogens, stimulate appetite, and maintain α-rhythm.
Endocrine:
- suppress the release of corticotropin (ACTH)
- reduces release of TSH, FSH, prolactin, and LH + T3-T4
- increased PTH
- reduce ADH effect on renal tubules => diuresis
- inhibit osteoblast function.
- inhibit insulin binding to insulin-receptors and the post-receptor effects of insulin.
Fluid and electrolyte balance:
- increase renal K+/Ca++ loss and NaCl reabsorption => increase ECF
GI tract and hepatic system:
- increase the secretion of gastric acid, pepsin, and trypsin. They alter the structure of mucin and decrease mucosal cell proliferation.
- reduce Fe and Ca++ absorbed
- increase fat absorbed.
Hepatic: increased fat and glycogen deposits in hepatocytes and increased (ALT), (GGT) and (ALP).
Hematopoietic system:
- increase circ PLT, neutrophils, and RBCs, but platelet aggregation is inhibited.
- Decreased amounts of lymphocytes (peripheral), monocytes, and eosinophils due to sequester these cells into the lungs and spleen
- involution of lymphoid tissue.
- inhibit neutrophil, macrophage, and monocyte migration; reduce production of interferon; and inhibit phagocytosis, chemotaxis, antigen processing, and intracellular killing.
- antagonize the complement cascade
- MCT reduced and histamine synthesis is suppressed.
Metabolic effects: Glucocorticoids stimulate gluconeogenesis. Lipogenesis is enhanced in certain areas of the body (eg, abdomen), and adipose tissue can be redistributed away from the extremities to the trunk. Fatty acids are mobilized from tissues and their oxidation is increased. Plasma levels of triglycerides, cholesterol, and glycerol are increased. Protein is mobilized from most areas of the body (not the liver).
Musculoskeletal:
muscular weakness, atrophy, and osteoporosis.
inhibited bone growth via growth hormone and somatomedin inhibition, increased calcium excretion, and inhibition of vitamin D activation. Resorption of bone can be enhanced. Fibrocartilage growth is also inhibited.
Skin: Thinning and skin atrophy.
Hair follicles can become distended and alopecia may occur.
What is the drug class and mechanism of action of
Beta adrenergic blocker
- relatively specific for B1
- Minimal B2 at recommended doses.
When is atenolol used?
- ventricular hypertrophy
- tachyarrhythmia including SVT, VPCs
- HCM/OHCM
+ mexiletine for ARVC
+/- systemic arterial hypertension, HCM and aortic/pulmonary stenosis
When should atenolol not be used?
- brady arrhythmias
with caution in patients with:
- CHF, CKD and sinus node dysfunction as is a negative ionotrope
- DM as can causes hyper/hypoglycaemia or mask signs of hyperT4 or hypoglycaemia.
What drugs are Beta blockers?
B1 selective:
- atenolol
- esmolol
- metoprolol
nonselective B blockers:
- carvediol,
- propranolol
- sotolol
What are the cardiac effects of B1 blockade?
Negative ionotrope
negative chronotrope
=> reduced HR + slow AV conduction
=> reduced CO, BP and myocardial O2 demands.
What are the effects of B2 blockade on CV and Resp system?
bronchospasm
peripheral vasodilation => hypotension.
What class is Esmolol and when should it be used?
ultrashort acting Beta (1) blocker - class II antiarrhythmic. - neg ionotroph and chronotrope => reduce HR, work , CO and BP
increases sinus cycle length, slow av node conduction and prolongs sinus recovery time.
For:
- SVT
- to see if Beta blocker therapy is needed
- under GA and risk of hypertension.
- hyperdynamic R vent outflow tract obstruction post balloon valvuloplasty for pulmonary valve stenosis.
When should esmolol not be used?
- Overt CHF
- second or 3rd degree AV blood
- sinus bradycardia
- cardiogenic shock
- bronchoconstriction
- DM
What class is metopralol and when should it be used?
second generation, Beta 1 blocker
used for:
- SVT or Afib for rate control
- VPC
- systemic hypertension
- HCM
When should metopralol not be used?
- unstable/overt CHF
- sensitive to beta blockers
- second or third degree AV block
- sinus bradycardia
care in:
- liver disease
- bronchospasm - less than propranolol so used more.
- CHF
- hyperT4
- DM
- sinus node dysfunction
What class is Carvediol and when should it be used?
nonselective B blocker
selective alpha 1 blocker
negative ionotrope
Class II antiarrhythmic
used fro :
- DCM to attenuate pacing induced DCM
- reduce Afib induction
When should carvediol not be used?
- unstable/overt CHF
- bronchial asthma
- sensitive to beta blockers
- second or third degree AV block
- sick sinus syndrome (unless paced)
- sinus bradycardia/severe brady cardia
- cardiogenic shock
What class is Propranolol and when should it be used?
nonspecific B blocker
selective alpha 1 blocker
negative ionotrope
Class II antiarrhythmic
used fro :
- short term management of thyrotoxicosis or phaeo
- hypertension
- B2 agonist toxicity (albuterol/terbutaline)
generally use other ones
When should propranolol not be used?
- unstable/overt CHF (unless secondary to tachyarrhythmia responsive to B blocker)
- bronchial asthma
- sensitive to beta blockers
- second or third degree AV block
- sick sinus syndrome (unless paced)
- sinus bradycardia/severe bradycardia
care in:
- liver/renal disease
- digitalis toxicity
- DM
- first degree AV blocks
- sinus node dysfunction
What class is Sotolol and when should it be used?
Non selective B blocker Potassium channel blocker (class III antiarrhythmic) - prolongs repolarization and refractoriness without affecting conduction
used for:
- long term oral management of ventricular tachycardia +/- mexiletine including ARVC, german shep with inherited arrhythmia and ventricular tachycardia that is refractory to IV antiarrhythmics.
- supraventricular tachycardia inc accessory pathway mediated reciprocating tachycardia, atrial-flutter and a cat with SVT
When should Sotolol not be used?
- unstable/overt CHF (unless secondary to tachyarrhythmia responsive to B blocker)
- bronchial asthma
- sensitive to beta blockers
- second or third degree AV block
- sick sinus syndrome (unless paced)
- sinus bradycardia/severe bradycardia
- hypokalaemic bradycardia
- long QT syndrome
- cardiogenic shock
care in:
- liver/renal disease
- digitalis toxicity
- DM
- first degree AV blocks
- sinus node dysfunction
What class is amidarone and when should it be used?
Class III antiarrhythmic (K+ channel inhibitor)
+ blocks Na+ and Ca++ channels
+ block B adrenergic receptors.
=> prolongs myocardial AP duration and refractory period.
only used when less toxic compounds not available.
- Cardioversion from Afib to sinus rhythm
- refractory arrhythmia wiht systolic dysfucntion.
+ itraconazole => treat trypanosoma cruzi (Chagas) due to disruption of calcium homeostasis, sterol production, and blockade of the protease cruzipain
When should amidarone not be used?
- unstable/overt CHF
- second or third degree AV block
- sick sinus syndrome
- sinus bradycardia/severe bradycardia esp if syncope
- cardiogenic shock
- iodine sensitivity
Care with thyroid disease - can cause hyper or hypothyroidism
can cause histamine reactions, pulmonary fibrosis, corneal deposits, thrombocytopenis, hepatotoxic, coombs +ve
What class is procainamide and when should it be used?
Class 1a antiarrhythmic
Procainamide prolongs the refractory times in both the atria and ventricles, decreases myocardial excitability, and depresses automaticity and conduction velocity
- negative inotrope but CO maintained.
- some anticholinergic effects
Used for
- SVT with wide QRS complex
- A-fib
- VPC
- V-tach
- tachycardias that cannot be confirmed to be supraventricular or ventricular in origin due to wide QRS.
When should procainamide not be used?
- myasthenia gravis
- hypersensitivity
- torsade de pointes
- 2nd or 3rd degree AV block (unlesss paced)
with caution in dogs with
- cardiac glycoside intoxication
- hepatic/renal disease
- CHF
- DCM
- subaortic stenosis
- patients susceptible to tachyarrhythmic -induced sudden death.
- SLE?
What class is triamterene and when should it be used?
K+ sparing diuretic
- distal renal tubule, triamterene inhibits the reabsorption of sodium in exchange for hydrogen and potassium ions
- doesn’t competitively inhibit aldosterone
- increases excretion of sodium, calcium, magnesium, and bicarbonate; urinary pH may be slightly increased.
- Serum concentrations of potassium and chloride may be increased
alternative to spironolactone
infrequently used
When should triamterene or amiloride not be used?
- anuria
- severe progressive renal disease
- severe hepatic diseas
- hypersensitivity
- pre-exisiting hyperkalaemia
- concurrent therapy with another potassium sparing agent
- potassium supplementation.
What class is amiloride and when should it be used?
K+ sparing diuretic
- blocks epithelial sodium channel the late distal tubule, connecting tubule and collecting duct => reduced absorption of Na+ and reduced excretion of K+
alternative to spironolactone.
What is the mechanism of action of vasopressin?
- acts through at least 5 different receptors (3 subtypes: V1, V2, V3; the oxytocin receptor; and the purinergic P2 receptor) to maintain serum osmolality.
- V2 receptors, vasopressin promotes the renal reabsorption of solute-free water in the distal convoluted tubules and collecting duct
- vasopressin V1 receptor stimulation and blockade of K+ -sensitive ATP channels can cause smooth muscle contraction = > vasoconstriction of capillaries and small arterioles in particular => decreased blood flow.
When is vasopressin used?
- diagnostics as part of water depreviation test.
- treatment for central DI
- CPR - can improve myocardial perfusion with no pulse.
- increase BP SIRS/sepsis associated hypotension.
When should vasopressin not be used?
- vascular disease
- seizure disorders
- heart failure
- asthma
- extravasation necrosis possible.