Clonidine

pharmacological · nervous · cardiovascular · Oral · Transdermal · IV

Clonidine. Non-selective α₂A/B/C agonist. Central sympathetic outflow reduction via brainstem α₂ → BP + HR decrease. Less-selective than… Oral half-life 8.5 h.

Non-selective α₂A/B/C agonist. Central sympathetic outflow reduction via brainstem α₂ → BP + HR decrease. Less-selective than guanfacine → more sedation / hypotension / dry mouth.

DOSE CORRECTED FROM A DELIVERY RATE STORED AS AN ABSOLUTE DOSE. The TD block read {"min":0.1,"max":0.3,"typical":0.167,"unit":"mg"}, which is the patch's mg/day strength, not the amount it delivers. This row already stores zo_dur_hr, so the wear interval was on the record while the dose contradicted it. Label verbatim: "Apply Catapres‑TTS ® (clonidine transdermal system) once every 7 days to a hairless area of intact skin on the upper outer arm or chest". Delivered over the interval that gives 0.7-2.1 mg, typical 1.169 mg — ARITHMETIC, rate x interval. Source: Catapres-TTS (clonidine transdermal system), DailyMed set id 39e1d35e-533c-4647-8649-8168a6e92dfa, v1 published 2026-03-31. A TRAP IN THE SAME TABLE: it prints "Programmed Delivery ... Per Day" of 0.1 mg beside a "Clonidine Content" of 3.09 mg for TTS-1. The content is what is in the patch, not what reaches the patient, and 3.09 mg is NOT the dose — 0.7 mg over the week is. THE CATALOG ALREADY DID THIS RIGHT ELSEWHERE, which is how the defect was spotted: nicotine stores 7-21 mg against a 24 h duration and rivastigmine 4.6-13.3 mg against 24 h, both being what the patch delivers over that interval rather than its hourly rate. PK: THE TRANSDERMAL LAG OF 48 HOURS IS DELETED AS A CATEGORY ERROR. It appears in no cited paper; its likely origin is a review sentence that maximum blood-pressure reduction occurs two to three DAYS after application — a time to maximum EFFECT under a week-long zero-order input, which is an emergent property of the model rather than an input delay. Keeping it would have delayed predicted concentrations by two days past data showing plasma rises immediately. THE REST OF THE PATCH PARAMETERISATION IS RIGHT AND IS KEPT: the 168 h zero-order duration is verbatim, "a relatively reproducible and consistent rate of 4.32 micrograms h-1 over a 7-day period", and its bioavailability of about 60% is a genuine intravenous-referenced absolute figure. The half-life of 12 h was the MIDPOINT of a stated 9.0 to 15.1 h range and is replaced by an intravenous-derived 8.5 h. F 0.85 matched none of the four published values and was not a midpoint of any; 0.752 is the adult intravenous-referenced figure. NO ADULT HUMAN VOLUME EXISTS in any abstract found — 181.5 L is size-standardised from a pooled PAEDIATRIC dataset that includes intravenous dosing, and it cross-checks against the adult clearance to within about 1%.

Pharmacokinetics

Sources: PMID:3293868, PMID:7128667, PMID:870272, PMID:17767627