Exam 2: Gustafson Lectures: Anticonvulsants and Chemo Flashcards
What is the drug of choice for treatment of seizure disorders in cats and dogs?
Phenobarbitol
diazepam if active
What is the drug of choice for anticonvulsants? What is a close second?
Diazepam (valium), Phenobarbital ext up but give IM which will make it reach brain slower.
Which drug is a well known inducer of microsomal cytochrome P450 (CYP450) enzymes? What is a negative effect o this?
Phenobarbitol
It interacts with other drugs, shortens their half life, and may not make the work as well.
You dog is presenting as sedation, plyphasia, polydipsia, polyuria… you just remembered you started them on a new drug. Which drug has these adverse effects?
Phenobarbitol
Not common to see hepatic toxicosis but you can.
Which drugs are used as an add-on with phenobarbitol and bromide? (not usually a monotherapy use)
Gabapentin, Levetiracetam (Keppra)
Anticonvulsants
What is the goal of anticonvulsant therapy?
Anticonvulsant suppress seizure activity and do not cause unconsciousness. Their general mechanism of action is that they prevent initiation or spread of seizure focus, raise seizure threshold, and inhibit excitatory neural activity. They do this by supressing nerve conduction, stabilizing neurons (so that there are less action potentials), and potentiate the effects of the inhibitory neurotransmitter GABA.
Anticonvulsants
What is the drug of choice for stabilization therapy in veterinary medicine?
Diazepam, valium. Phenobarbtiol is a second but most commonly used in chronic cases. Bromide last maybe in combination with the first two.
Anticonvulsants
What are the mechanism of actions for the major drugs used in the treatment of seizures in veterinary medicine?
they bind to specific GABAa receptors and increase the efficacy of endogenous GABA on the GABAa receptors (same amt of GABA will have greater inhibitory effect when drug is bound)
Anticonvulsants
What are the potential adverse effects associated with the drugs primarily used to treat seizures in dogs?
Diazepam: tolerance (tachyphylaxis) during chronic treatment, sedation/ behavioral changes, hepatic toxicosis in cats during chronic oral treatment (Potentially from toxic metabolite), generally safer than barbiturates and difficult to fatally overdose.
Phenobarbital: Sedation, Polyphagia (increased eating), Polydipsia (increased thirst), Polyuria (increased urination), (These may subside over the first few weeks due to tolerance and increased hepatic metabolism). Induction of CYP450 enzymes, elevated hepatic enzymes like alkaline phosphatase both toxic and non-toxic, bilirubin, and serum levels are also increased. Elevated bilirubin and toxins can lower seizure thresholds, hepatocutaneous syndrome (superficial necrolytic dermatitis). monitor liver when giving.
Bromide: polyphagia (increased eating), behavior changes, sedation. Bromism (bromide toxicosis): CNS depression (sedation, weakness, ataxia), joint stiffness in rear limbs, coughing (cats)
Anticonvulsants
What is the primary drug used for maintenance therapy for seizures in veterinary medicine?
phenobarbitol
Anticonvulsants
What potential drug interactions exist for the drugs used to treat seizures in veterinary medicine?
For Phenobarbitol: digoxin, steroids, and chloramphenicol
Cancer Chemotherapy I
What is the “selective basis” for cancer chemotherapy?
Attempting to use drug therapy to kill mammalian cells that actually arose from the organism that you are trying to treat…. Selectivity is based on very small differences in cell growth, recovery potential and in relatively rare cases a driving mutation to which the cancer is addicted.
Cancer Chemotherapy I
Be able to define how chemotherapy is used clinically to treat cancer. For example, how does neoadjuvant therapy differ from adjuvant therapy?
- Induction – Initial treatment to bring about remission
- Consolidation – To kill remaining cancer cells (intensification or post-remission therapy)
- Maintenance – Enhance primary response and prevent relapse
- Salvage – Treatment after primary therapy fails
- Adjuvant – Treatment when there is no measurable disease to suppress secondary tumor formation. Generally thought of as treatment after surgical resection
- Neoadjuvant – Treatment prior to surgery to shrink or “pretreat” tumor
- Radio-sensitization – To enhance the response of ionizing radiation
- Palliation – Treatment to ease symptoms without curative intent
Cancer Chemotherapy I
What are the goals associated with cancer therapy and how does the treatment regimen coincide with this goal?
Cure – all cancer cells have been eradicated
Remission – clinical evidence of cancer has disappeared, BUT…microscopic foci likely remain
Palliation – treatment to reduce pain, improve function.
Therapeutic regimen must be consistent with the goal of treatment**
Cancer Chemotherapy I
Describe the basis of combination cancer chemotherapy and the characteristics of a favorable vs. unfavorable drug combination protocol.
The basis of combination chemotherapy is to treat with more intensive cycles of therapy without exacerbating normal tissue toxicity or recovery.
Thus combination protocols should:
Combine agents with complimentary activity
Combine agents without overlapping toxicity
