Attention deficit hyperactivity disorder
Clonidine may improve symptoms of attention deficit hyperactivity disorder in some people but causes many adverse effects and the beneficial effect is modest. In Australia, clonidine is an accepted but not approved use for ADHD by the TGA. Clonidine, along with methylphenidate, has been studied for treatment of ADHD. While not as effective as methylphenidate in treating ADHD, clonidine does offer some benefit; it can also be useful in combination with stimulant medications. Some studies show clonidine to be more sedating than guanfacine, which may be better at bedtime along with an arousing stimulant in the morning. Clonidine has been used to reduce sleep disturbances in ADHD, including to help offset stimulant-associated insomnia. Drug withdrawal
Clonidine may be used to ease drug withdrawal symptoms associated with abruptly stopping the long-term use of opioids, alcohol, benzodiazepines and nicotine. It can alleviate opioid withdrawal symptoms by reducing the sympathetic nervous system response such as tachycardia and hypertension, hyperhidrosis (excessive sweating), hot and cold flashes, and akathisia. It may also be helpful in aiding smokers to quit. The sedation effect is also useful. However, its side effects can sometimes include insomnia, thus exacerbating an already common feature of most withdrawal syndromes. Clonidine may also reduce severity of neonatal abstinence syndrome in infants born to mothers that are using certain drugs, particularly opioids. In infants with neonatal withdrawal syndrome, clonidine may improve the neonatal intensive care unit Network Neurobehavioral Score.Clonidine has also been suggested as a treatment for rare instances of dexmedetomidine withdrawal.
Because the PFC is required for working memory and attention, it is thought that clonidines inhibition of PFC neurons helps to eliminate irrelevant attention (and subsequent behaviors), improving the persons focus and correcting deficits in attention. Growth hormone test
Clonidine stimulates release of HGH hormone from the hypothalamus, which in turn stimulates pituitary release of growth hormone. This effect has been used as part of a "growth hormone test," which can assist with diagnosing growth hormone deficiency in children. Pharmacokinetics
After being ingested, clonidine is absorbed into the blood stream rapidly and nearly completely, with peak concentrations in human plasma occurring within 60–90 minutes for the "Immediate Release" (IR) version of the drug, which is shorter than the "Extended Release" (ER/XR) version. Clonidine is fairly lipid soluble with the logarithm of its partition coefficient (log P) equal to 1.6; to compare, the optimal log P to allow a drug that is active in the human central nervous system to penetrate the blood brain barrier is 2.0. Less than half of the absorbed portion of an orally administered dose will be metabolized by the liver into inactive metabolites, with roughly the other half being excreted unchanged by the kidneys. About one-fifth of an oral dose will not be absorbed, and is thus excreted in the feces. The half-life of clonidine varies widely, with estimates between 6 and 23 hours, and is greatly affected by and prolonged in the setting of poor kidney function. History
Clonidine was introduced in 1966.