Acute Porphyrias Flashcards

1
Q

The acute porphyrias are ______________ disorders of ____________ biosynthesis

A

Hereditary

Haem

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2
Q

What are the different acute porphyrias? (4)

A
  1. Acute intermittent porphyria
  2. Variegate porphyria
  3. Hereditary coproporphyria
  4. 5-aminolaevulinic acid dehydratase deficiency porphyria
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3
Q

What is the prevalence of acute porphyrias?

A

1 in 75 000

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4
Q

Great care must be taken when ___________ for patients with acute porphyria, since certain ___________ can induce acute porphyric crises

A

prescribing

drugs

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5
Q

Since acute porphyrias are hereditary, _______________ should be screened and advised about the potential danger of certain drugs

A

relatives of affected individuals

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6
Q

Where there is no safe alternative, drug treatment for serious or life-threatening conditions ________________ patients with acute porphyria

A

should not be withheld from

  • Where possible, the clinical situation should be discussed with a porphyria specialist for advice on how to proceed and monitor the patient
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7
Q

________________ is administered by short intravenous infusion as haem replacement in moderate, severe, or unremitting acute porphyria crises

A

Haem arginate

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8
Q

What are the clinical manifestations of acute porphyria? (8)

A
  1. Severe abdominal pain
  2. Pain in chest, back, or legs
  3. Constipation or diarrhea
  4. N/V
  5. Muscle pain, tingling, numbness, weakness, or paralysis
  6. Red or brown urine
  7. Mental changes such as anxiety, confusion, hallucinations, disorientation, or paranoia
  8. Sensitivity to sunlight
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9
Q

What causes the symptoms of acute porphyrias?

A

Buildup of porphyrin and porphyrin precursors in the liver, skin, and other body tissues

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10
Q

What happens in acute porphyria attacks eg those induced by certain drugs?

A

Something eg a drug stimulates the enzymes in the porphyrin pathway, leading to a rapid increase in porphyrins in the blood and tissues

This triggers a period of severe symptoms that may require hospitalization and can be life-threatening without treatment

Attacks often start with severe abdominal, back, or thigh pain and can last 1-2 weeks

May cause neurological problems such as paralysis

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11
Q

How does haem arginate help reduce the symptoms of acute porphyria?

A

Because it is a complete haem, this drug slows down the production of porphyrins, thereby reducing the number of toxic intermediate circulating and depositing in the system

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12
Q

What are the drug GROUPS that are considered unsafe to take for patients with acute porphyria? (11)

A
  1. Anabolic steroids
  2. Antidepressants including MAOIs and TCAs
  3. Barbiturates
  4. Hormonal contraceptives, progestogens, and HRT
  5. Imidazole antifungals
  6. NNRITs
  7. Proteases inhibitors
  8. Sulfonamides
  9. Sulfonylureas
    * *(glipizide and glimepiride are thought to be SAFE)
  10. Taxanes
  11. Triazole antifungals
    * *(topical antifungals are thought to be safe due to low systemic exposure)
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13
Q

Which sulfonylureas are considered safe for use in patients with acute porphyrias? (2)

A
  1. Glipizide

2. Glimepiride

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14
Q

Although systemic antifungals are known to trigger attacks of acute porphyria, ______________ use is considered safe

A

Topical

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15
Q

In addition to the drug groups considered unsafe for use in acute porphyria, how many other drugs are known to trigger acute attacks?

A

76

Check the BNF treatment summaries page OR contraindications of specific drugs

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