Substitution self-administration

The pharmacological properties of phenylethylamines that control selfadministration are complex. The effects of phenylethylamines on a variety of pharmacological measures do not appear to predict the reinforcing effects of these drugs, as measured by the cocaine substitution procedure in primates. Specifically, none of the following behavioral effects of these compounds accurately predict the results of self-administration experiments within the phenylethylamine class (Griffiths et al. 1976 Griffiths et al. 

Animal and human studies have demonstrated that the self-administration of palatable foods, especially sweets, increases after nicotine deprivation (Hughes et al. 1991 Ogden and Fox 1994 Spring et al. 2003). In abstinent human smokers, the reward value of carbohydrate-rich snack foods were higher in females than males, suggesting that food and nicotine may be substitutable rewards, especially for females (Spring et al. 2003). 

Many studies have shown that DA neurons in the mesocortico-limbic system play an important role in mediating the reinforcing actions of cocaine. DA lesions in VTA or Acb markedly attenuate cocaine self-administration of cocaine in animal models. DA antagonists diminish the reinforcing action of cocaine. DA agonists (especially at the D1 or D2 receptors) will substitute for cocaine. Animals (and humans) will self-administer certain DA agonists. 

Young, Gerald A., George F. Steinfels, and Naim Khazan. 1978. Transitional Patterns of Self-Administration Following Substitution of Methadone or L-Alpha-Acetylmethadol (LAAM) for Morphine in Dependent Rats." Drug and Alcohol Dependence 3 273-79. 

Self-administration studies can be initiated in one of two ways direct self-administration or substitution. In the direct self-administration procedure, inexperienced subjects are given access to a test drug, and the extent to which self-administration is initiated and maintained is measured and can be compared to the rate of behavior observed when placebo and/or other drugs are available. In the more commonly used substitution procedure, self-administration of a standard or prototypic abused drug is established first the test drug is then substituted for the standard drug, and changes in self-administration behavior are measured. 

Use of an appropriate self-administration paradigm, such as the substitution procedure described above,... 

Insulin Aspart is a second fast-acting engineered human insulin analogue now approved for general medical use. It differs from native human insulin in that the proline residue has been replaced by aspartic acid. This single amino acid substitution also decreases the propensity of individual molecules to self-associate, ensuring that they begin to enter the bloodstream from the site of injection immediately upon administration. 

The administration of these sterile products and ease of use have become a much more important criterion in recent times. This trend is expected to continue, as will the move towards drug delivery devices intended for easier application, with an increasing focus on self-application. These containers/drug delivery devices will inevitably use an increasing number of plastic components so that any complexity is involved in the assembly of the system rather than in the use of the delivery device. Rubber components have a significant role to play in the successful development of such devices, since there is no real substitute for rubber. 

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