Lecture

• The CNS has excitatory and inhibitory neurotransmitters
• Brainstem contains: midbrain, pons and medulla oblongata
• Pons is involved in sensory and motor functions and receives info from the RF or RAS; regulates respirations and sleep
• Gamma aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the CNS; accounts for 50% of inhibitory action. It functions by binding to a chloride channel to open it up and hyperpolarize the intracellular membrane
• Benzodiazepines is an anxiolytic and act as a CNS depressant. Binds to receptors chloride channels and increases frequency of chloride channel opening. It has sedative, hypnotic, anxiolytic and anticonvulsive effects. Works on the limbic system, RAS, cerebral cortex and spinal cord
• How benzos/GABA work on the limbic system: GABA prevents excessive activation which decreases feelings of anxiety and fear, while benzos have a calming effect and more controlled mental state
• how benzos/GABA effects the RF: the RF controls the degree of wakefulness/alertness. Each of those cause sedative effects which means a person will become drowsy and slow to react
• Cerebral cortex is responsible for higher level thinking. Excessive stimulation leads to seizures so GABA/benzos have an inhibitory role. Benzos inhibit the chances of seizure through continuous inhibition but can also terminate an active seizure
• Midazolam is carried by ACPs for controlling seizures and are used to sedate combative PTs or for procedural reasons
• Anti-convulsant benzos: Lorazepam (Ativan), diazepam(valium), clonazepam(rivotril) and midazolam(Versed)
• How Benzodiazepines affects the spinal cord: increase the affects of GABA on the spinal cord which decreases skeletal muscle tone. Used to treat back pain, muscular injuries, SCIs, muscular dystrophy and cerebral palsy
• Common benzodiazepines: alprazolam(Xanax), chlordiazepoxide(Librium), Clonazepam(Rivotril), diazepam(Valium), Lorazepam(Ativan), midazolam(Versed), temazepam(Restoril), flurazepam(Dalmane)
• Benzos used for anxiety disorder: Alprazolam(Xanax), chlordiazepoxide(Librium) and lorazepam(ativan) and diazepam(valium). Out of these diazepam is also used to treat seizures
• Benzos used to treat seizures: clonazepam(rivotril) and diazepam(valium). Diazepam is also used to treat anxiety
• Midazolam(versed) is the only benzo used as an anesthetic
• temazepam(restoril) and flurazepam(Dalmane) are benzos used to treat insomnia
• Peripherally acting muscle relaxants work at the NMJ and within the skeletal muscle fibers
• Centrally acting muscle relaxants depress the reflex impulse conduction within the spina cord
• Centrally acting skeletal muscle relaxants adverse effects: causes CNS depression and anticholinergic effects such as hypotension and bradycardia. They also have a high potential for abuse, especially benzodiazepines
• Cyclobenzaprine(flexeril) seems to have a stronger sedative effect than the other ones
• Methocarbamol(Robax/Robaxacet): a central muscle relaxant that is often taken over the counter. Has 2 trades names because methocarbamol is an ingredient mixed up with other substances for either of them
• Central acting muscle relaxants: baclofen, chlordiazepoxide(Librium), cyclobenaprine(Flexeril), methocarbamol(Robxa/Robaxacet) and Orphenadrine(Norflex)
• Types of general seizures: tonic clonic, myoclonic, atonic and absent(looking away and staring). In some seizures a PT may not lose consciousness
• Seizures are broadly divided into general and partial
• There are 2 types of drugs for seizures: anticonvulsants and antiepileptics
• Anticonvulsants are used to terminate convulsive seizures and are usually administered IV/IM
• Antiepileptics are prophylactic for the prevention of epilepsy induced seizure. Administered PO and fxn by decreasing excitability of brain cells to decrease incidence and severity of seizures
• Seizure meds: carbamazepine(Tegretol), Phenobarbital(Phenobarb), phenytoin(Dilantin), topiramate(Topamax), valproic acid/divalproex(Depakene/Epival), Gabapentin(neurontin), clonazepam(rivotril), diazepam(valium) and midazolam(versed)
• Seizure meds used for status epilepticus: diazepam(valium), midazolam(Versed) and clonazepam(rivotril). Clonazepam is also used for absent seizures
• Gabapentin(Neurontin) is the only drug that is used for only partial seizures
• Carbamazepine(tegretol), phenobarbital(Phenobarb), phenytoin(Dilantin), topramate(topamax) and valproic acid/divalproex(Depakene/Epival) are used for tonic clonic and partial seizures. Out of these, valproic acid/divalproex(Depakene/Epival) is the only one that also treats absent seizures
• valproic acid/divalproex(Depakene/Epival) and clonazepam(Rivotril) treat absent seizures
• Barbituates are sedative hypnotics that bind to GABA receptors to increase the chloride Ion channel opening duration. (differs from benzos as benzos increase frequency rather than duration)
• Barbitutates are useful in controlling seizures
• At higher doses, barbituates cause profound CNS depression
• Barbituate toxic dose is not that much higher than the therapeutic dose so this is concerning for anyone with compromised metabolism or accidental ODs
• At lower doses, barbituate may cause side effects that seem like alcohol intoxication
• Hydantoins decrease Na+ ions in the cell; reduces ability to fire off action potentials. Phenytoin(Dilantin) is the primary drug from this group and its very potent. Used in tx of all types of partial and tonic clonic seizures. Big advantage is that it causes very little sedation
• Carbapmazepine(tegretol) has a similar action to phenytoin(dilantin) and used to treat different types of epilepsy and seizures
• Valproic acid/divalproex(Depakene/Epival) decreases the influx of Na+ ions and blocks the excitatory glutamate receptors and increases GABA. Causes very little sedation and used in all types of epilepsy/seizures