Saturday, February 17, 2018

Methamphetamine-CNS stimulant



                                             METHAPHETAMINE

Methamphetamine (contracted from N-methylamphetamine) is a strong central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a treatment for attention deficit hyperactivity disorder and obesity. Methamphetamine was discovered in 1893 and exists as two enantiomers: levo-methamphetamine and dextro-methamphetamine

   MEDICAL USE

 the United States, methamphetamine hydrochloride, under the trade name Desoxyn, has been approved by the FDA for treatingADHD and obesity in both adults and children;[21][22] however, the FDA also indicates that the limited therapeutic usefulness of methamphetamine should be weighed against the inherent risks associated with its use.[21] Methamphetamine is sometimes prescribed off label for narcolepsy and idiopathic hypersomnia.[23][24] In the United States, methamphetamine's levorotary form is available in some over-the-counter (OTC) nasal decongestant products



Contraindications
Methamphetamine is contraindicated in individuals with a history of substance use disorderheart disease, or severe agitation or anxiety, or in individuals currently experiencingarteriosclerosisglaucomahyperthyroidism, or severe hypertension.[21] The USFDA states that individuals who have experienced hypersensitivity reactions to other stimulants in the past or are currently taking monoamine oxidase inhibitors should not take methamphetamine.[21] The USFDA also advises individuals with bipolar disorderdepression, elevated blood pressure, liver or kidney problems, maniapsychosisRaynaud's phenomenonseizuresthyroid problems, tics, or Tourette syndrome to monitor their symptoms while taking methamphetamine.[21] Due to the potential for stunted growth, the USFDA advises monitoring the height and weight of growing children and adolescents during treatment.[21]

Overdose
A methamphetamine overdose may result in a wide range of symptoms.amoderate overdose of methamphetamine may induce symptoms such as: abnormal heart rhythm, confusion, difficult and/or painful urination, high or low blood pressure, high body temperatureover-active and/or over-responsive reflexesmuscle aches, severe agitationrapid breathingtremorurinahesitancy,and URINE

Interactions
Methamphetamine is metabolized by the liver enzyme CYP2D6, so CYP2D6 inhibitors will prolong the elimination half-life of methamphetamine.Methamphetamine also interacts with monoamine oxidase inhibitors (MAOIs), since both MAOIs and methamphetamine increase plasma catecholamines; therefore, concurrent use of both is dangerous] Methamphetamine may decrease the effects of sedatives and depressants and increase the effects of antidepressants and other stimulants as well.]Methamphetamine may counteract the effects of antihypertensives and antipsychotics due to its effects on the cardiovascular system and cognition respectively

PHARMACOKINETICS
Following oral administration, methamphetamine is well-absorbed into the bloodstream, with peak plasma methamphetamine concentrations achieved in approximately 3.13–6.3 hours post ingestion.[106] Methamphetamine is also well absorbed following inhalation and following intranasal administration.] Due to the high lipophilicity of methamphetamine, it can readily move through the blood–brain barrier faster than other stimulants, where it is more resistant to degradation by monoamine oxidase]The amphetamine metabolite peaks at 10–24 hours.It is excreted by the kidneys, with the rate of excretion into the urine heavily influenced by urinary pH.When taken orally, 30–54% of the dose is excreted in urine as methamphetamine and 10–23% as amphetamine.Following IV doses, about 45% is excreted as methamphetamine and 7% as amphetamine.The half-life of methamphetamine is variable with a range of 5–30 hours.



Methamphetamine side effects
Get emergency medical help if you have signs of an allergic reaction to methamphetamine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Methamphetamine can affect growth in children. Tell your doctor if your child is not growing at a normal rate while using this medicine.
Stop using this medicine and call your doctor at once if you have:
·         chest pain, trouble breathing, feeling like you might pass out;
·         hallucinations (seeing or hearing things that are not real), new behavior problems, aggression, hostility, paranoia;
·         a seizure (convulsions);
·         numbness, pain, cold feeling, unexplained wounds, or skin color changes (pale, red, or blue appearance) in your fingers or toes;

Referance- Tripathi K.D,"Essentials of medical pharmacology",7th edition,page no-134,135


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