dietary influence

• An overview of therapeutic classes of drugs
• Pharmacodynamics


  What the drug does to the body
• Pharmacokinetics


  How the body handles the drug
• Therapeutic classes of drugs (by body systems)

  • GI & Hepatobiliary System
  • CV & Haematopoietic System
  • Respiratory System
  • CNS
  • MSK system
  • Anti-Infectives (systemic)
  • Endocrine & metabolic system
• Drugs for GIT (common drugs)

  • Aluminium hydroxide; Ranitidine (Antacids for gastric & peptic ulcers)
  • Loperamide (Imodium®) (Anti-diarrhoea for acute & chronic diarrhoea)
  • Hyoscine (Buscopan®) (Anti-spasmodics for abdominal pain, cramps)
  • Bisacodyl (Dulcolax®); Lactulose (Laxatives for constipation)
  • Domperidone; Ondansetron (Dantron®) (Anti-emetics for N, V)

  
• Blood disorders


  • Anaemia (low RBC)
  • Bleeding disorders (haemophilia, blood clots)
  • Blood cancers (leukaemia, lymphoma, myeloma)
  • Nutritional imbalanced (hyperglycaemia, hypercholesterolemia)
• Drugs for CV & haematopoietic systems

  • Diuretics (for HYP, congestive heart failure, oedema) (Frusemide; Hydrochlorothiazide)
  • ACE Inhibitors (for hypertension, congestive heart failure) (Captopril; Enalapril)
  • Angiotensin-II antagonists (for hypertension, congestive heart failure) (Losartan; Candesartan)
  • Dyslipidaemic agents (for hyperlipidaemia) (Lovastatin; Atorvastatin (Lipitor®))
  • Anti-coagulants (Warfarin)

  
• Respiratory agents


  • Anti-asthmatic & COPD preparations (Ketotifen; Ipratropium (Atrovent®); Salbutamol (Ventolin®), Theophylline)
  • Cough & cold preparations (Tripolidine + Pseudoephedrine (Actifed®))
  • Nasal decongestants & other nasal preparations (Oxymetazoline (Afrin®))
• Drugs for CNS


  • Anticonvulsant (Phenytoin; Carbamazepine (Tegretol®))
  • Hypnotics-sedative (Zolpidem (Stilnox®))
  • Anti-vertigo drug (Promethazine (Stemetil®); Cinnarizine (Stugeron®))
  • Analgesics (opioid) (Tramadol; Codeine; Morphine)
  • Non-steroidal anti-inflammatory drugs (NSAIDs) (Etoricoxib (Arcoxia®); Mefenamicacid (Ponstan®))

  
• MSK system disorders


  • Muscular dystrophy
  • Osteoporosis
  • Rheumatic disorders
  • Myasthenia gravis
  • Gout
  • Tetany
• Drugs for MSK system

  • Hyperuricemia & Gout Preparations (Allopurinol (Zyloric®))
  • Neuromuscular Disorder Drugs (Pyridostigmine (Mestinon®))
  • Muscle Relaxants (Baclofen (Lioresal®); paracetamol + orphenadrine (Norgesic®))

  
• Anti-infective drugs


  • Macrolides (Erythromycin; Azithromycin)
  • Penicillin (Amoxicillin; Amoxicillin + Clavulanic acid (Augmentin®))
  • Anti-fungal (Fluconazole; Miconazole)
  • Anthelmintics (Albendazole (Zentel®))
  • Anti-viral (Acyclovir)

  
• Drugs for endocrine & metabolic disease

  • Insulin Preparations
  • Anti-diabetic agents (Acarbose; Rosiglitazone (Avandia®); Metformin (Glucophage®))

  
• Other therapeutic classes


  • Genito-Urinary System
  • Contraceptive Agents
  • Oncology
  • Vitamins & minerals
  • Nutrition
  • Eye & ear / mouth / throat
  • Dermatology
  • Anaesthetics - local & general
  • Allergy & immune system
  • Antidotes, detoxifying agents & substance dependence
  • intravenous & other sterile solutions
• Drug interaction


  When a patient's response to a drug is modified by food, nutritional supplements, formulation excipients, environmental factors, other drugs or disease

  
• Types of drug interactions

  • Behavioural
  • Pharmaceutical
  • Pharmacokinetics
  • Pharmacodynamics
• Behavioural interactions


  Occur when one drug alters the patient's behaviour to modify compliance with another drug
• Pharmaceutical interactions


  Occur when the formulation of one drug is altered by another before it is administered
• Pharmacokinetic interactions


  Occur when one drug changes the systemic concentration of another drug, altering 'how much' and for 'how long' it is present at the site of action
• Pharmacodynamic interactions


  Occur when interacting drugs have either additive effects, in which case the overall effect is increased, or opposing effects, in which case the overall effect is decreased or even 'cancelled out'
• Bioavailability (pharmacokinetic interactions)


  Occurs when the amount of the object drug reaching the systemic circulation is affected by a perpetrator drug

  
• Clearance (pharmacokinetic interactions)


  Occurs when the metabolism or excretion of the object drug (esp. those with narrow therapeutic index) is affected by a perpetrator drug
• Distribution (pharmacokinetic interactions)


  Occurs when the concentration of drug at the site of action is changed without necessarily altering its circulating concentration
• Pharmacodynamic interactions


  Occur between drugs with additive or opposing effects
• Licorice (glycyrrhizin) can cause potassium levels in the body to fall, leading to abnormal heart rhythms, high BP, oedema, lethargy, congestive HF
• Chocolate contains flavanols (antioxidant), theobromine, caffeine (stimulant), tyramine, phenylethylamine (CNS stimulant), and the amino acid L-tryptophan which increases serotonin in the brain (calming effects)
• Excessive chocolate can interact with MAO inhibitors


  Causing tyramine increase, hence HYP & other related symptoms
• Caffeine in chocolate


  Can interact with stimulant drugs e.g. Ritalin (methylphenidate), increasing their effects
• Chocolate


  Can reduce the effect of sedative-hypnotics such as Ambien (zolpidem)
• Alcohol has both pharmacodynamic and pharmacokinetic interactions with drugs
• Alcohol


  Increases CNS depression and sedation when combined with opioid analgesics e.g. methadone and codeine derivatives
• Short-term alcohol use


  Acts as an enzyme inhibitor
• Chronic and heavy alcohol use

  Acts as an enzyme inducer, accelerating the metabolism of other drugs
• Alcohol metabolism


  Alcohol is metabolised to acetaldehyde (toxic metabolite) to acetate
• Inhibition of acetaldehyde metabolism to acetate

  Results in accumulation of acetaldehyde, causing facial flushing, tachycardia, diaphoresis, headache (disulfiram-like effects)
• Alcohol


  Suppresses gluconeogenesis (synthesis of glucose), increasing the risk of hypoglycaemia in diabetic patients taking anti-diabetic medications

  
• Alcohol


  Exacerbates the adverse effects of anti-hypertensive medications, increasing the risk of orthostatic (postural) hypotension
• Alcohol


  Further increases the risk of GI bleeding when combined with NSAIDs and aspirin
• Metronidazole


  Causes disulfiram-like effects when combined with alcohol, also interacts with 2nd generation cephalosporins
• Alcohol and warfarin


  Depending on frequency of consumption, alcohol can lead to an increase or decrease in the anti-coagulant effect of warfarin