Barbiturates dependence potential

These drugs comprise the barbiturates, alcohols and a new class of cyclopyrrolone hypnotics. Because of the severity of their side effects and their dependence potential, the barbiturates should not be used to treat insomnia. 

Schedule 11 drugs have an accepted medical use in the United States and a high rate of abuse, with either severe psychological or physical dependence potential. These drugs include morphine, codeine, cocaine, amphetamine, and most barbiturate preparations containing amobarbital, secobarbital, and pentobarbital. 

The various barbiturates differ m the time required for the onset of sleep and m the duration of their effects All the barbiturates must be used only m strict accordance with instructions to avoid potentially lethal overdoses Drug dependence m some mdi viduals IS also a problem... 

Like the barbiturates, the miscellaneous drugp sedative or hypnotic effects diminish after approximately 2 weeks. Ffersons taking these dragp for periods longer than 2 weeks may have a tendency to increase the dose to produce the desired effects (eg, sleep, sedation). Physical and psychological dependence may occur, especially after prolonged use of high doses. However, their addictive potential appears to be less than that of the... 

Schedule III—The drug or other substance has (1) a potential for abuse less than the drugs or other substances in Schedules I and II, (2) a currently accepted medical use in treatment in the United States, and (3) abuse of the drug or other substance may lead to moderate or low physical dependence or high psychological dependence. Examples ketamine, anabolic steroids, some barbiturates. 

The side effects of barbiturates include sedation, poor physical coordination, and impaired mental performance. They also potentiate the intoxicating effects of alcohol. Barbiturates can be extremely dangerous in overdose, causing anesthesia, coma, and even death. In addition, barbiturates can cause dangerous suppression of breathing in patients with sleep apnea or other respiratory disorders. With repeated use over just a few weeks, physical dependence and tolerance to their effects can develop, leading to increasing doses to maintain the desired therapeutic effect. If a... 

The potential side effects of benzodiazepines include dizziness, lack of coordination, and, at higher doses, amnesia. Benzodiazepines also increase the effects of alcohol drinking alcohol shonld therefore be avoided. Benzodiazepines can also worsen the breathing problems of patients with sleep apnea and other respiratory disorders such as emphysema. Like the barbiturates, long-term nse of benzodiazepines can lead to physical dependence. The major advance of benzodiazepines... 

Due to their narrower margin of safety (risk of misuse for suicide) and their potential to produce physical dependence, barbiturates are no longer or only rarely used as hypnotics. Dependence on them has all the characteristics of an addiction (p. 210). 

Schedule II (c-/7) - High abuse potential with severe dependence liability (eg, narcotics, amphetamines, dronabinol, some barbiturates). 

Geriatric Considerations - Summary Because barbiturates have a low therapeutic window, a wide range of drug interactions and rapid development of folerance, great potential for abuse and dependence, fhese agents are not recommended for use in older adulfs. 

The principal disadvantages of barbiturates as hypnotics include the development of physical dependence, a relatively low therapeutic index (and the potential of poisoning, as in suicide), suppression of REM sleep, and possible hangover effects. As mentioned above, benzodiazepines (e.g., flurazepam or brotizolam) are hypnotics as effective as barbiturates and are much safer in terms of their therapeutic index, addiction potential, and REM sleep-deprivation effects. Thus benzodiazepines have displaced barbiturates as sedative hypnotics. 

Hangover especially with long acting barbiturates. Excitement and restlessness, neuralgic pain, allergic reactions include swelling and erythematous dermatitis. They produce physical dependent and have abuse potential. 

Schedule II - The drugs at this level also have a high abuse potential and could cause psychic or physical dependence. They may be prescribed but are under stringent control. Schedule II drugs include opioids(morphine), amphetamines and methamphetamines used alone or in combination as well as some barbiturates. 

Schedule III - These chemicals have less abuse potential that those in the first two categories but their abuse may lead to moderate or low physical dependence or high psychological dependence. Examples are certain opiods in limited quantities (codeine), and some nonopiods such as glutethimide(sedative), phendimetrazine(diet aide), and some barbiturates. 

Phenobarbital, mephobarbital and metarbital are the only oral anticonvulsants which are effective at sub-hypnotic levels. Many barbiturates are classified as Schedule II, III, or IV due to their high potential for overdose and dependence. Abrupt withdrawal may cause seizures, restlessness, trembling, and insomnia and may be fatal. Phenobarbital is used as an anticonvulsant for the treatment of epilepsy and in some combination medications for the relief of irritable bowel syndrome. 

Tolerance, physical dependence and addiction are possible with the benzodiazepines but less likely to occur than with barbiturates. In general this class of compounds does not cause induction. The potential for suicide is also lessened with these compounds. It has been estimated that physical dependence occurs in one person out of five million. Withdrawal symptoms are real but usually not life-threatening (fatigue due to REM rebound, dizziness, CNS disturbances). In general, benzodiazepines do not cause induction. 

Schedule 3 involves drugs with a significant abuse potential, but lower than for Schedules 1 and 2. Such drugs may lead to moderate or low physical dependence or high psychological dependence. Examples include many stimulants such as amphetamines and methamphetamines as well as various barbiturates. Anabolic steroids (used by athletes and bodybuilders) are also included because of their serious health risks. 

Schedule IV. These drugs supposedly have a lower potential for abuse than schedule III drugs, with only a limited possibility of physical dependence, psychologic dependence, or both. Examples include certain antianxiety drugs (meprobamate), certain barbiturates (barbital, phenobarbital), and a variety of other depressants and stimulants. 

Schedule II drags have a high potential for abuse. They are accepted for medical use with restrictions. These drugs may lead to severe psychological or physical dependence. Barbiturates in this category are amo-barbital (Amytal), pentobarbital (Nembutal), and secobarbital (Seconal, Tuinal). 

Schedule IV drugs have a low abuse potential as compared to Schedule m drugs. These substances have an accepted medical use. They could lead to limited psychological or physical dependence, according to the CSA. The Schedule IV barbiturates are barbital (Veronel), mephobarbital (Mebaral), and phenobarbital (Luminal). Five prescription refills are allowed during the six months after the patient received the first prescription. 

Topiramate blocks repetitive firing of cultured spinal cord neurons, as do phenytoin and carbamazepine. Its mechanism of action, therefore, is likely to involve blocking of voltage-dependent sodium channels. Topiramate also appears to potentiate the inhibitory effect of GABA, acting at a site different from the benzodiazepine or barbiturate sites. Topiramate also depresses the excitatory action of kainate on AMPA receptors. It is possible that all three of these actions contribute to topiramate s anticonvulsant effect. 

---