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Pharm1Test3Barb
Pharm1 Test3 Barbiturates Barry
Question | Answer |
---|---|
Oxygen is what percentage of air? | 21%. |
Increasing altitude decreases O2. How does this affect diffusion into tissues? | It decreases. |
How do hyperbaric chambers work? | Increasing PO2 increases O2 delivery into tissues. |
Normally hemoglobin is how saturated? | 98%. |
What are the four causes of oxygen deficiency? | 1. low inspired fraction (FIO2), 2. increased diffusional barrier 3. hypoventilation 4. ventilation – perfusion mismatch |
What are the five effects of hypoxia? | 1. Increased ventilation 2. sympathetic stimulation 3. pulmonary vasoconstriction to optimize V/Q 4. impaired CNS function 5. anerobic metabolism |
Hypoxia causes sympathetic stimulation. What results from this stimulation? | Tachycardia, but decreased peripheral vascular resistance. This is a local effect. |
Hypoxia causes anerobic metabolism. What results from prolonged anerobic metabolism? | Increased lactic acid, decreased ionic gradients – increased cell H+, Ca++, Na+ leading to cell death. |
What is the main use of oxygen? | To reverse or prevent hypoxia. |
True or false: due to dissociation curve, increased inspired O2 concentration does not greatly increase blood O2. | True. |
Overexposure to oxygen can cause toxicity, probably due to formation of... | Peroxide. |
Carbon dioxide is part of what buffer system? | Bicarbonate buffer system. |
Increasing PCO2 leads to... | Respiratory acidosis. |
Decreasing PCO2 leads to... | Respiratory alkalosis. |
What is another word for hypocarbia? | Respiratory alkalosis. |
When would you use hypocarbia to decrease cerebral vessels and decrease brain size somewhat? | Neurosurgery. |
When would we use carbon dioxide during cardiac surgery? | To reduce air (insoluble N2) around heart. |
True or false: sudden high calcium levels is an indicator for cell death? | True. |
True or false: CO2 therapy is frequently used to stimulate respirations. | False. |
Nitric oxide is used in the cells as a... | Signaling molecule. |
What is the main driving mechanism for the dilation of many arterioles? | Nitric oxide. |
Nitric Oxide can cause large pulmonary dilation with minimal systemic effects | dsfj |
Helium is an inert gas. What are its three main uses? | Pulmonary function testing, laser airway surgery, and diving. |
What are sedative? | Agents which cause mild suppression of arousal and behavior, and a slight decrease in alertness and response to stimuli. |
What are hypnotics? | Agents which cause pronounced sedative effects including the induction of sleep. |
True or false: patients receiving hypnotics are usually arousable to painful stimuli. | True. |
Most hypnotics are simply sedatives... | Given in larger doses. |
Nitric oxide has minimal systemic side effects. The main systemic side effect is... | Binds to and inactivates oxyhemoglobin. |
Normal sleep has at least two phases, which are? | Slow wave sleep(SWS) and rapid eye movement sleep(REM). |
What happens in slow wave sleep? | EEG shows mainly high-voltage synchronous activity. |
Describe rapid eye movement sleep: | Skeletal muscles are relaxed (inhibited) and the eyes move back and forth rapidly. Accounts for ~ 25% of sleep. |
What are the three effects of hypnotics on sleep? | 1. SWS patterns are altered and shortened. 2. REM sleep is depressed 3. Total sleep time is prolonged. |
True or false: Benzodiazepines bind to the GABA-a receptor complex at the same site as the Barbiturates. | False. Benzodiazepines bind to the GABA-a receptor complex at a different site as the Barbiturates. |
How do the Barbiturates act on GABA? | Decreases the dissociation rate of GABA from its binding site, thus increasing the duration of action of GABA at the receptor, and increasing chloride conductance. |
True or false: Barbiturates have been reported to be able to mimic the action of GABA at the GABA-a receptor, this is a strong effect. | False. While Barbiturates have been reported to be able to mimic the action of GABA at the GABA-a receptor, this is minimal, and major effects require GABA. |
In addition to decreasing the dissociating rate of GABA, Barbiturates also inhibit... | Excitatory glutamate AMPA receptors. |
The parent compound of Barbiturates is Barbituric Acid. What are its sedative qualities? | It has none. |
What forms does Barbituric Acid take? | Keto and enol (tautomers) |
You can affect the sedative/hypnotic qualities of a Barbiturate by adding functional groups onto what position? | Position 5. |
The Thiobarbiturates are more lipid-soluble. How are they made? | Replacement of C-2 oxygen with sulfur. |
Phenobarbitol is a Barbiturate with anticonvulsent properties. How is it made? | Addition of a phenol group at C-5. |
How can you change the chemical structure of a Barbuturate to shorten its duration of action? | Addition of a methyl group to the ring N atom. |
What is the long-duration Barbiturate? | Phenobarbital (Luminal). |
What are the intermediate-duration Barbiturates? | Pentobarbital (Nembutal) and Secobarbital (Seconal). |
What are the short-duration Barbiturates? | Methohexital (Brevital) and Thiopental (Pentothal). |
True or false: Barbiturates are weak bases. | False. Barbiturates are weak acids. |
The basic way to chemically package Barbiturates is as a... | Sodium salt. |
A solution of Barbiturate is bacteriostatic why? | Because of its high pH(packaged as a basic sodium salt). |
Why do Barbiturates only last for a few weeks after being opened? | Because after exposure to air acid precipitates out because CO2 in air alters pH of solution. |
True or false: More lipid soluble Barbiturates have shorter onset due to rapid increase in brain conc., followed by rapid redistribution to body tissues. | True. |
Most Barbiturates are metabolized to a large extent. What is the primary metabolic pathway? | Hydroxylation to inactive metabolites. |
What is the half-life of Phenobarbitol? | 86 hours. |
In addition to the hydroxylation pathway, Barbiturates are also metabolized (to a larger extent by Asians) by what pathway? | N-glucosylation. |
Barbiturates are potent inducers of what in the liver? | The hepatic microsomal enzyme system. |
What is the result of Barbiturates' induction of hepatic microsomal enzyme system? | An increased metabolic rate of barbiturates as well as other drugs normally metabolized by this system(oral anticoagulants, phenytoin, TCA). |
Why do we use Barbiturates? | Induction of anesthesia, anticonvulsants, Neuropsychiatric exams(Wada Speech Test) prior to neurosurgery, cerebral edema and brain protection. |
How do Barbiturates effect pregnancy? | Fetal blood levels usually well under maternal levels, but placental transfer does occur. Fetal elimination much slower than mother. |
Why has use of Barbiturates declined? | 1. Benzodiazepine’s are safer and just as effective. 2. Drug interactions (due to enzyme induction) 3. Tolerance development 4. Greater abuse potential 5. Less CNS specificity than Benzodiazepines |
How do we currently use Barbiturates? | 1. Therapeutic/diagnostic aids in psychiatry 2. Reduction of cerebral edema following surgery, head injury or cerebral ischema 3. Antiepileptic use. |
Thiopental(Pentothal) is an ultra-short acting, highly lipid soluble Barbituate. How long until induction? | 10-15 seconds. |
Thiopental(Pentothal) is rapidly distributed into the brain due to high blood flow. It is then quickly redistributed where? | Fatty tissues. This accounts for its short effect. |
Why do we use Thiopental(Pentothal)? | Induction and short cases. |
Thiopental has a half-life of 6 hours. Where is it metabolized? | By the P-450 system in the liver. |
How do repeated doses of Thiopental(Pentothal) increase the duration of action? | Because the body's storage centers (fatty tissues) fill up. |
True or false: Thiopental(Pentothal) reduces pain threshold, sensitizing the body to pain. | True. |
True or false: Thiopental(Pentothal) has muscle relaxant effects. | False. This drug has very poor skeletal muscle effects. |
True or false: Thiopental(Pentothal) is a respiratory depressant, leading to a period of apnea on induction. | True. |
How does Thiopental(Pentothal) decrease blood pressure? | Depressing the myocardium and relaxing smooth muscle in the vasculature. |
True or false: we are currently on a Thiopental(Pentothal) shortage. | True. |
How does Methohexatol(Brevitol) compare in potency to Thiopental(Pentothal)? | It is three times as potent. |
Both are metabolized by the P-450 system. Why is Methohexatol(Brevitol) metabolized more quickly than Thiopental(Pentothal)? | Methohexitol(Brevitol) is less lipid-soluble than Thiopental(Pentothal)? |
True or false: Methoxital(Brevitol) has a faster recovery than Thiopental after multiple doses? | True. |