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Drugs for Obesity

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الكلية كلية الطب     القسم  الادوية     المرحلة 3
أستاذ المادة انتصار جواد حمد المختار       21/06/2018 13:44:33
Drugs for Obesity
Dr.Entisar Al-Mukhtar

Anorexiants (appetite suppressants): Phentermine & Diethylpropion
MOA:
• Phentermine increases NE and dopamine release and inhibiting their reuptake, the increase in NE signals a “fight-or-flight” response, in turn decreases appetite.
• Diethylpropion has similar effects on NE. Tolerance to the weight loss effect develops within weeks. Discontinuation of the drug is usually recommended once the weight loss plateau is reached.
Pharmacokinetics:
• Diethylpropion undergoes extensive 1st pass metabolism. Many of the metabolites are active, excreted mainly via the kidneys.
Adverse effects:
• The anorexiants are controlled substances (potential for dependence or abuse).
• HR and BP may be increased (should be avoided in patients with a history of uncontrolled HT, CV disease, arrhythmias, HF, or stroke).
• anorexiants used with MAOIs or other sympathomimetics should be avoided.

Lipase inhibitors
Orlistat is the only available lipase inhibitors, its indicated for long-term weight management (up to 4 years ).
• gastrointestinal adverse effects limits its clinical utility.
MOA:
Inhibits gastric & pancreatic lipases decreasing dietary fat break-down, decreasing fat absorption by about 30%. Its GI adverse effects may also contribute to an overall decreased intake of food.
Pharmacokinetics:
• Taken orally with each fatty meal.
• save in patients with renal or hepatic dysfunction.
Adverse effects:
• Oily spotting, flatulence with discharge, fecal urgency & increased defecation, low-fat diet & concomitant cholestyramine use minimized these effects.
• Contraindication: (1) pregnancy (2) chronic malabsorption syndrome (3) cholestasis.
Drug interaction:
• interferes with fat-soluble vitamins (A, D, E, and K) and ?-carotene absorption, thus multivitamin supplement and ?-carotene should be taken (after at least 2 hours of orlistat).
• interfere with the absorption of amiodarone, cyclosporine & levothyroxine.
Serotonin agonists
Lorcaserin is a newer serotonin agonist, has selectivity for 5-HT2C, used for chronic weight management.
Previous serotonin agonists used for weight loss were pulled from the market due to an increase in potentially fatal adverse effects, including valvular heart disease which may lead to pulmonary hypertension. It is believed that valvulopathy, is linked to 5-HT2B receptors.

MOA:
• activates 5-HT2C receptors (in the CNS ), thereby activate melanocortin receptors & decreasing appetite.
Pharmacokinetics:
not recommended in severe renal impairment.
Adverse effects:
• Patients should be monitored for the emergence of life-threatening serotonin syndrome or neuroleptic malignant syndrome.
• concomitant use of lorcaserin with SSRIs, serotonin–NE reuptake inhibitors, MAOIs, or other serotonergic drugs should be avoided.
the incidence of valvulopathy was not significantly increased in studies of lorcaserin (5-HT2C receptor agonist).
• patients should be monitored for the development of valvulopathy (hence, lorcaserin should be used cautiously with a history of HF).
Combination drugs
• The phentermine / topiramate combination has been approved for long-term use.
• the stimulant phentermine was added to counteract the sedating effects of topiramate and promote additional weight loss.
• This medication should not be stopped abruptly as seizures may be precipitated.
• Topiramate has been associated with birth defects including cleft palate, thus, the combination is contraindicated in pregnancy.
• Topiramate can cause paresthesias, suicidal ideation, and cognitive dysfunction.
• increased HR may be observed with the phentermine component.
Drug interactions:
• MAOIs should be avoided (possibility of serotonin syndrome with phentermine).
• Non–potassium-sparing diuretics used with this combination may increase hypokalemia risk.
• Topiramate is a weak carbonic anhydrase inhibitor, thus the use of other carbonic anhydrase inhibitors with this combination increases the risk of kidney stones.
• Topiramate may reduce OCs efficacy, given a risk of birth defects.


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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