Hypotension: Postprandial and Orthostatic

Kiran Panesar, BPharmS (Hons), MRPharmS, RPh, CPh

Disclosures

US Pharmacist 

In This Article

Postprandial Hypotension

A patient is said to have PPH if he or she experiences a fall in systolic BP of at least 20 mmHg or more in a supine/sitting position within 120 minutes following a meal.[10] While PPH is distinct from OH, both may exist in the same patient.[10] PPH is common in the elderly as well as in those with Parkinson's disease or a disorder of the autonomic system.[9] It is thought that PPH may occur through one or more of the following mechanisms: release of vasodilatory peptides in the gastrointestinal (GI) tract, impairment of the baroreceptor reflex, peripheral vasoconstriction, inadequate CO postprandially, or increased postprandial splanchnic blood.[11] The size, content, timing and temperature of the meal all seem to affect PPH (Table 2).[9,12] Pharmacists can advise patients to try remaining in a supine position following a meal. Specifically, this may help those who have both OH and PPH.[12] Particularly in the elderly, adequate hydration is essential in preventing PPH.[12] Effective treatment options are presently scarce and relatively limited.[13] Up until recently, medications such as caffeine and octreotide were used; acarbose is only just being tested.

Caffeine

There is inconclusive and conflicting evidence to establish the use of caffeine for the management of PPH.[9,10,12] While it is thought that caffeine antagonizes the effects of vasodilators, its mechanism is not fully understood.[9,14] However, if given before a meal, it may reduce the postprandial fall in BP in some patients. Effective doses range from 60 to 200 mg (about one to two cups of coffee). Since tea and coffee are readily available and relatively cheap, caffeine is worth trying in patients who are affected by PPH. Caffeine is associated with side effects such as diarrhea, tremors, sleep disorders, and tachycardia.

Octreotide

Octreotide has established its use in elderly hypertensive patients with PPH and in those with autonomic failure. Its effect is thought to be mediated through a direct increase in splanchnic blood flow and forearm vascular resistance as well as the blockage of intestinal and pancreatic hormones.[9,12,14] Octreotide, however, is relatively expensive and is administered as a single premeal dose of 25 to 50 mcg via subcutaneous injection. The patient may experience pain at the site of injection as well as diarrhea, nausea, and alopecia.[12]

Acarbose

Acarbose has been shown to reduce PPH in patients with autonomic failure.[14] In part, it is thought that by decreasing the breakdown of complex carbohydrates, acarbose inhibits the action of alpha-glucosidase. This results in the decreased secretion of insulin, which has a vasodilatory effect, as well as other GI hormones. This finding may explain why the carbohydrate portion of a meal exerts the greatest hypotensive effect.[14] The normal dose is 100 mg of acarbose taken 20 minutes before meals three times a day. Common side effects include abdominal pain, diarrhea, and flatulence.

A number of drugs, including midodrine, dihydroergotamine, indomethacin, diphenhydramine, cimetidine, fludrocortisone, and vasopressin, have all given variable results in different studies for the management of PPH.[12]

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