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 disorder, heart disease, or severe agitation or anxiety, or in individuals currently experiencingarteriosclerosis, glaucoma, hyperthyroidism, 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 disorder, depression, elevated blood pressure, liver or kidney problems, mania, psychosis, Raynaud's phenomenon, seizures, thyroid 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 temperature, over-active and/or over-responsive reflexes, muscle aches, severe agitation, rapid breathing, tremor, urinahesitancy,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